Making No-Till Wheat Production Profitable:  On-Farm Testing

No-Tillage Wheat

No-Tillage Wheat - Long-Term Effects

Yield of Winter Wheat in a Long-Term Continuous No-Tillage Rotation of Corn, Wheat & Double-Crop Soybean

Comparative Performance of Wheat Varieties in No-Till and Conventional-Till Trials

Residue Placement to Improve Yields of No-Tillage Winter Wheat Following Corn

Residue Management for No-Till Wheat

Nitrogen Management for No-Tillage Wheat Following Corn or Full-Season Soybean

Tillage and the Nitrogen Requirement of Wheat Following Full-Season Soybean

Tillage and Nitrogen Management for Wheat Planted at Different Dates

Wheat Seeding Rate Study

Fusarium Head Blight Survey 1998-99

Greenhouse and Field Evaluation of Resistance to Fusarium Head Blight in Soft Red Winter Wheat

1998-99 National Fusarium Head Blight Uniform Fungicide Test

1998-99 Wheat Seed Treatment Test

Can Aphid Control Reduce Barley Yellow Dwarf Incidence in Wheat?  A Case Study (Caldwell Co., Ky 1998-99)

The Affect of Insecticide Application Timing for Controlling Aphid Vectors on Barley Yellow Dwarf Incidence on Wheat Grown in Henderson Co., Ky

Managing Annual Italian Ryegrass with Preharvest Applications

Impact of Wheat Herbicides on Double-Cropped Soybeans

1999 Nutrient Survey of Wheat

In 1997, the KySGGA established the goal of having 75% of the state's wheat acreage managed using no-till methods by the year 2005. Before that dramatic change can occur, producers must be convinced that they will not have to sacrifice short-term economic viability in order to gain the long-term benefits of topsoil conservation attainable using no-till methods. Hence, this project's goal was to compare some tillage (ST) and no-tillage (NT) wheat production systems, both under intensive management, for profitability.

Table 1 compares the two tillage systems. Yields, on average across the 7 tests, were 3.0 bushels/A higher for ST, resulting in $8.60 greater value per acre. Tillage and stalk chopping cost an average of $25/A for ST, while extra seed, herbicide, and N fertility cost an average of $14.80/A for NT. On the whole, this resulted in a slight economic advantage ($1.60/A) for NT methods.

The attached footnotes for Table 1 discuss some assumptions made in this analysis. Most importantly, no dollar benefit was assigned to the topsoil saved by NT methods. Of course, another year's data could dramatically change the above profit comparison. Market price changes could help to some extent; for example, if the market price had been $4.00/bu across the 1998 and 1999 seasons, the comparison would have shown a $1.80 advantage for ST.

We plan to repeat this study at 4 locations in the 1999-2000 growing season, in order to assess this tillage comparison under different environmental conditions. To this point, our results appear to provide some incentive for growers to consider moving toward a no-till system. However, we do note this caution: The previously funded on-farm tillage comparisons in the 1996-97 growing season resulted in an average of 65 bushels/A for ST and 58 bushels/A for NT. These grower-managed tests produced 12% less grain under NT management, while our 1997-99 consultant (or researcher) managed tests only produced 4% less grain under NT management. It appears that no-till may respond to more careful management than some growers have been willing to implement.

Based on our work to this point, it looks like the slight yield loss for NT wheat production is more than covered by the savings producers would have in tillage costs. We are planning to continue this work for the 1999-2000 wheat production season.
 

TABLE 1. ECONOMIC SUMMARY OF ON-FARM TILLAGE COMPARISONS FUNDED BY KySGGA/KySGPB IN 1997 THROUGH 1999
		ST advantage		Additional ST costs		Additional NT costs
Test	Managed by:	Yield	Value	Residue Mgmt	Tillage	Seed	Herbicide	Nitrogen	Net ST Benefit
		(Bu/ac)		------------------------------------$/Acre--------------------------------
'98 Daviess	OC	+0.2	+0.6	6	22	0.9	15	0	-11.5
'98 Fayette	UK	+4.9	+14.2	0	22	9.1	0	5.6	+6.9
'98 Logan	WT	+6.1	+17.7	0	22	10.7	0	0	+6.4
'99 Caldwell	UK	+5.6	+15.7	6	25	4.4	0	3.2	-7.7
'99 Daviess	OC	-3.7	-10.4	6	22	5.8	15	0	-17.6
'99 Fayette	UK	+1.5	+4.2	0	22	7.1	2.2	4.2	-4.3
'99 Logan	WT	+6.4	+17.9	0	22	12.4	7.9	0	+16.2
Means	UK/OC/WT	+3.0	+8.6	2.6	22.4	7.2	5.7	1.9	-1.6

1. Abbreviations: ST, some tillage; NT, no-tillage; OC, Miles Opti-Crop; UK, University of Kentucky; and WT, Wheat Tech.

2. Expenses which were in common were not considered in this analysis, as the goal of the project was to compare economic advantages of the two tillage systems.

3. No economic credit was given for the long-term economic advantage likely to result from use of no-tillage methods (through the conservation of topsoil).

4. No economic credit was given for the potential benefits of no-tillage methods to rotated corn and soybean crops.

5. We assumed that neither test weight nor harvest moisture were influenced by tillage system.

6. Both ST and NT were managed to optimize their profitability rather than to obtain the highest possible yields.

7. Specific practices employed (i.e., the type and number of tillage passes) are shown in detail in the attached summaries of individual test locations.

8. Each location included two varieties and two replications. Calculated yield differences between tillage systems are assumed to represent real differences.

9. In five of the above tests, the later maturing variety produced higher yields than did the earlier maturing variety (within a given location). Rather than picking the better variety to paint this economic collage, we averaged across the two (to make our conclusions more supportable).

10. This data should be interpreted with some caution, as environmental conditions in coming seasons could clearly affect the outcomes of the two tillage systems. (However, some management considerations may have already helped buffer NT wheat from winterkill; for example, none of these 7 tests were planted in early October, and that may have helped account for the similar survival of most NT tillers in the face of a severe spring freeze in early March, 1998.)

11. In 1998, we used a market price of $2.90/bushel. The income deficiency payment for 1999 tests brought the value of the 1999 crop to $2.80/bushel.

12. No adjustments were made for differing speed of operations; for example, ST was not penalized for slightly slower combining, nor was NT penalized for slower speeds while drilling the crop.

OBJECTIVE:

The objective of this experiment is to see if high yields can be produced by no-till wheat and to see if no-till wheat is an economical alternative to conventionally planted wheat on a long-term basis. The experiment includes different tillage methods, nitrogen rates and herbicides.

METHODS:

The experiment is at Princeton, Ky on a Pembroke silt loam soil that is moderately well drained. Pioneer 2540 was planted on Oct. 12 at 35 seeds/sq. Ft. Conventional plots were chisel plowed and disked twice. The plots were 10 ft. x 30 ft. The soil test was pH 6.0, P-39, and K-247 and 0-60-30 lb/ac. As N-P₂O₅-K₂O was applied before planting. Warrior insecticide was sprayed at 3 oz/ac and Tilt was sprayed at 4 oz/ac at heading.

RESULTS:

There were no differences between the yields of no-tillage and conventional planted wheat. The highest yielding treatment was no-tillage wheat with 120 lbs/ac of N. However, the average of all conventional planted treatments was 2 bu/ac higher than the same no-tillage treatments.

The seven-year average is 5.0 bu/ac greater with conventional tillage planting.
 

YIELDS ACCORDING TO TILLAGE
Treatment	1999 Yields (bu/ac)	Yields ('93-'99)
Conventional	89.3 a	92.7
No-Till	87.3 a	87.7

Nitrogen was managed for intensive production with 1/3 of the N applied at Feekes 3 and the remainder at Feekes 5. Conventionally planted wheat yields were not effected by the nitrogen rate. However, the 120 lb/ac of N rate was necessary for highest yields with no-tillage planting.

The above normal temperatures for most of the winter and spray may have resulted in more fertilizer N being immobilized in the surface residue. This is the third year of seven that the highest N rate resulted in a significantly higher yield with no-till wheat.
 

YIELDS ACCORDING TO NITROGEN RATE
Treatment (lb/ac)	Yields (bu/ac)	Yields ('93-'99)
No-till 90	83.0 b	85.6
No-till 120	91.6 a	88.3
Conv. 90	88.4 a	91.1
Conv. 120	90.3 a	93.3

In 1996, a split N application of 60-60 in February and March was a better combination than the 40-80 split. To look at this nitrogen timing in more detail, several treatments with different timings were added.

The 0-60-60 (Fall-Feb.-March) treatment has been similar to all the other treatments the last two years. In fact, there was no difference between any of the treatments in 1999.

The fall application of N has never been an advantage in any of the four years. The 0-0-120 (Fall-Feb.-March) treatment yields were as good as any. The warm fall and winter encouraged tillering so early N was not necessary this year for this variety.
 

YIELDS ACCORDING TO TIME AND PLACEMENT OF NITROGEN APPLICATION
Treatment (lb/ac)			Yields (bu/ac)	Yields ('97-'99)
Fall	February	March
0	40	80	93.8 a	88.6
0	60	60	88.7 a	86.2
30	30	60	94.1 a	85.4
30	45	45	83.6 a	84.9
0	0	120	87.1 a

On April 20, 1999 weed control was evaluated based on the percent ground cover occupied by weeds in the row middles. Henbit and common chickweed were the dominant weeds observed. Other species noted in the spring included annual bluegrass, curly dock, field pepper weed, hairy bittercress, hairy chess, shepherd's-purse, star-of-Bethlehem, wild carrot, catchweed bedstraw, and speedwell.

The overall weed control observed in conventional-till wheat with spring Harmony Extra was essentially equal to that found in no-till wheat with fall applied Gramoxone Extra followed by spring applied Harmony Extra. Weed control with Harmony Extra was substantially better when applied in the fall compared to when it was applied in the spring. Plots treated in the fall with Sencor at 4 oz/A had very little henbit or chickweed, but did have other weeds, particularly wild carrot.

Wheat yields for all weed management practices exceeded 90 bu/ac in 1999. The yields of plots receiving a herbicide treatment were similar and were at least 5.5 bu/ac greater than the yield of no-till wheat where no herbicide was used. The seven-year averages for wheat yield tended to be less with Harmony Extra applied in the spring compared to other weed management practices, however, this trend was not observed in 1999.
 

EFFECT OF WEED MANAGEMENT ON THE PRESENCE OF WEEDS  AND WHEAT YIELDS
Weed Management	1999 Weed Cover (%)1			Wheat Yield (bu/ac)
	Henbit	Chickweed	Total Weeds	1999	'93-'99
Conventional Till Spring Harmony Extra	11 ab	4 bc	20 de	90.3 a
No-till Fall Harmony Extra	4 b	0 c	10 e	92.4 a	89.7
No-till Spring Harmony Extra	27 a	15 ab	52 b	90.4 a	88.2
No-till Fall Sencor	4 b	2 c	37 c	92.7 a	.....
No-till Fall Gramoxone Extra Spring Harmony Extra	17 ab	4 bc	27 cd	91.6 a	90.1
No-till No Herbicides	28 a	18 a	76 a	84.8 b	76.6
1Gramoxone Extra at 1.5 pt/A was applied on Oct. 12, 1998. Fall Harmony Extra at 0.5 oz/A & Sencor at 4 oz/A were applied Nov. 18, 1998. Spring Harmony Extra at 0.5 oz/A was applied March 29, 1999. 2Weed Control was evaluated on April 20, 1999 based on a visual rating of percent ground cover occupied by weeds in the row middles.

Fungicide applications were managed for intensive production on all treatments and there were no differences observed in disease among the treatments.

Insect pests were not a significant factor on this test this year. Plots were monitored weekly for the presence of insect pests including aphids, cereal leaf beetle and armyworm. However, no populations of any importance developed. To prevent Barley Yellow Dwarf, Warrior was sprayed 30 and 60 days after planting.

The fall stand counts over a six-year average show about 10% less plants in the no-till plots as compared to the conventional plots when planted at the same rate. This year, stand counts were high in both tillage methods, but no-till was 13% less than the tilled method of planting.
 
 

WHEAT STANDS (Plants/Sq. Ft.)
Treatment	Fall - 1999	Fall - 6-years avg.
No-till	30.2	26.4
Conventional	34.8 a	28.8

Head counts made at maturity were significantly higher for the no-till planting. The number of heads/ft² were in the range where high yields might be expected for both tillage treatments. It appears that the wheat plant with no-tillage tillered more than the conventional wheat since fall stands were lower with no-tillage.
 

Treatment	Head Counts Heads/ft2	1993-99 Average
No-till	70.8 a	63.3
Conventional	66.2 b	65.2

OBJECTIVE:

The objective of this experiment was to verify the effects of no-till wheat and tilled wheat on the subsequent yield of soybeans and corn planted after wheat in a wheat, double-cropped soybean and corn rotation and measure differences in fertility and physical effects on the soil on a long-term basis.

METHODS:

The experiment is at Princeton, Ky on a Pembroke silt loam soil that is moderately well drained. Wheat was planted no-tilled and with tillage and the tillage plots were chisel plowed and disked twice. The plots were 10 ft x 30 ft. The soil test was pH - 6.0, P - 39, and K - 247 and 0-60-30 lbs/ac of N-P₂O₅-K₂O was applied before planting. Soybeans are planted no-till immediately after wheat harvest and no-till corn is planted the following year and wheat (tilled and no-tilled) is again planted after corn harvest.

RESULTS:

The data (below) indicates that both no-till corn and no-till soybeans tend to yield more (3.8% for soybeans and 6.3% for corn) where the wheat is planted no-till. However, the differences are not always statistically significant, but the trend has remained consistent since the second year of the experiment.

The data indicates that changes in the system which have taken place in the two systems is more favorable for these crops when planted after no-till wheat. The reason for the difference is not clear at this time, but might include residue cover, soil moisture, soil physical changes, or others.

The soil density and the soil strength have been measured each year and both of these measures show very similar readings with little or no differences between the two systems indicating that compaction is not a problem in either system.

The amount of soil organic matter found in the two systems was very similar. There is also no difference in the soil test pH, phosphorus or potassium between the two systems. The total no-tillage system 0.24% more organic matter in the top 3 inches of the soil than the one with tilled wheat.

Temperature loggers were placed at different heights and depths within the soil and wheat canopy to develop a temperature profile that might help answer questions concerning the differences between tilled and no-tilled wheat on growth vigor and winterkill.

In 1998-99, there was no difference in the vegetative growth between the two tillage systems and there was also little difference in temperatures most of the time. The temperatures in both tillage systems declined in December at the same rate and began rising in late January at the same rate.
 

EFFECT OF WHEAT TILLAGE SYSTEMS ON THE YIELD OF SUCCEEDING CROPS
Year	Wheat Tillage System
	No-Till	Conventional
Soybeans (bu/ac)
1999	14.9	15.4 N.S.*
1998	16.5	15.8 N.S.
1997	45.1	42.7 N.S.
1996	54.5	50.8 N.S.
1995	24.4	22.2 N.S.
1994	49.5	51.6 **
Average	34.2	33.1
Corn (bu/ac)
1999	196.0	165.7 **
1998	203.7	190.2 **
1997	211.9	199.3 **
1996	--- Harvest Data Lost ---
1995	186.0	191.0 N.S.
1994	206.0	178.0 **
Average	200.7	184.8
* N.S. means no significantly statistical differences. ** Statistically different at the 0.1% level.

CONCLUSIONS:

No-tillage wheat seems to have a favorable effect on the yields of the subsequent crops (corn and soybeans) planted in the rotation. Yields of these two crops are increased about 4 to 6% on the average when planted after no-till wheat. The reason of this is unclear at this time. The temperature extremes are greater under the no-tillage wheat planting which can increase the changes of freeze damage.
 

 

YIELD OF WINTER WHEAT IN A LONG-TERM CONTINUOUS
NO-TILLAGE ROTATION OF CORN, WHEAT AND DOUBLE-CROP SOYBEAN

OBJECTIVE:

Determine the economic contribution of wheat to the long-term productivity of the 3 crops/2years rotation.

METHODS:

Location: Fayette County/Spindletop
Soil Type and Drainage: Maury silt loam - well drained
Previous Crop: Corn
Tillage: No-Tillage (Lilliston 9680)
Cultivar: Pioneer 2552
Planting Date & Rate: Nov. 5, 1998; 26.5 seed/sq.ft.
Harvest Date: June 21, 1999
Fertilizer: Nitrogen - 40 lb N/ac as 34-0-0 on 12/15/98
                                40 lb N/ac as 34-0-0 on 3/2/99
                                80 lb N/ac as 34-0-0 on 4/5/99
Herbicides: Gramoxone Extra - 1 qt/ac on 10/23/98
Harmony Extra - 0.7oz/ac on 4/7/99
Brominal ME4 - 0.75 pt/ac on 4/7/99
Fungicides: Tilt 3.2EC - 4 fl oz/ac on 5/15/99
Results: Average of 4 replications - 39.0 bu/acre

CONCLUSIONS:

Yields were poor, primarily because later planting caused crop development to be more greatly influenced by the drought. Both vegetative growth and kernel size were below expectations. Historically, the yield of no-tilllage wheat in these plots has been negatively related to the yield of the previous corn crop. Average yield losses appear to be about 1 bu/ac of wheat for every 10 bu/ac in the preceding corn crop, with annual corn yields ranging between 90 and 190 bu/ac and annual wheat yields averaging between 40 and 80 bu/ac. The poor wheat yields observed in 1990 and 1999 were excluded from the relationship. This negative relationship probably exists because greater corn yields result in greater corn residue levels, which hinder wheat stand establishment and may reduce/delay wheat tillering.
 

OBJECTIVE:

To determine whether wheat varieties that are superior under conventional tillage are also superior under no-tillage.
 

METHODS:
 

Location	Logan Co.	Caldwell Co.	Shelby Co.
Harvest Year	1998	1999	1998-99
Cooperator	W. G. Farms	Gilkey Farms	Ellis Farms
Previous Crop	Corn	Corn	Corn
Conventional Tillage	Disk-ripper, Disk, Cultipacker	Disk-ripper, Disk, Cultipacker	Chisel Plow, Disk
Stubble Condition (no-till)	Flail-mowed	Flail-mowed	Standing
Planting Date	10/8/97	10/9/98	10/1/97; 10/12/98

Entries consisted of 46 commercial and public soft red winter wheat varieties in 1998 and 43 in 1999. Twenty-eight varieties were common to both years. Each variety was replicated 4 times at each location in both years. Conventional tests were planted with a 6-row cone seeder with double-disk openers in 7 " rows. Plot area was 60 square feet. No-till plots were seeded with a 7-row cone seeder equipped with John Deere 750 openers in a row spacing of 7.5 ". Plot area was 240 square feet. Seeding rates were approximately 325 seeds/sq. yd. for conventional tillage and 365 seeds/sq. yd. for no-till. Inputs such as fertilizer and pesticides were similar to those used by the cooperating farmers on their commercial wheat fields.

RESULTS:

Variety yield means are presented in the following three tables.

CONCLUSIONS:

There was very good agreement between no-till and conventional-till performance in terms of variety mean yield. For example, the correlation between no-till and conventional-till performance over two years in Shelby Co. was 0.85 (Table 1). Perfect agreement would have yielded a correlation coefficient of 1.0. When comparing no-till vs. conventional-till performance in Logan Co. in 1998 and Caldwell Co. in 1999, the correlation was 0.74 (Table 2). When data from all three locations in both years were considered, the correlation was 0.88 (Table 3). The take home message at present is that, in general, superior varieties will perform well under either tillage system. However, we will continue to test wheat varieties under conventional and no-till management in the foreseeable future.
 

TABLE 1. SHELBY COUNTY NO-TILL AND CONVENTIONAL VARIETY TRIAL, 1998-99
	CONV: YIELD (BU/A)			NO-TILL: YIELD (BU/A)
VARIETY	1999	1998	MEAN	1999	1998	MEAN
2540	87.2	61.6	74.4	82.9	63.5	73.2
2552	98.3	65.1	81.7	100.4	64.2	82.3
2568	90.6	51.9	71.3	89.9	55.7	72.8
25R26	88.4	57.4	72.9	89.3	56.0	72.7
AG FOSTER & GAUCHO	81.0	43.5	62.3	77.6	50.7	64.2
AGRIPRO ELKHART	78.6	45.8	62.2	87.6	44.5	66.1
AGRIPRO FOSTER	79.4	43.2	61.3	72.7	46.7	59.7
AGRIPRO MASON	86.5	53.1	69.8	84.0	49.6	66.8
AGRIPRO PATTON	94.9	62.3	78.6	99.5	59.0	79.3
BECK 103	73.3	46.6	60.0	81.4	45.7	63.6
BECKER	66.8	41.9	54.4	79.2	46.2	62.7
CALDWELL	61.2	34.1	47.7	54.1	29.7	41.9
CLARK	76.1	48.5	62.3	82.1	40.6	61.4
COKER 9474	70.0	40.5	55.3	79.6	41.1	60.4
COKER 9663	83.0	52.2	67.6	93.7	57.4	75.6
FFR 522	75.8	45.8	60.8	75.2	42.1	58.7
FFR 555	80.6	42.1	61.4	83.0	47.9	65.5
FFR 558	75.2	44.6	59.9	79.7	50.0	64.9
GLORY	87.3	57.2	72.3	86.3	60.5	73.4
HYTEST W9850	80.5	53.4	67.0	79.3	57.9	68.6
JACKSON	84.1	40.7	62.4	87.2	42.6	64.9
KAS JUSTICE	66.5	45.2	55.9	75.7	49.5	62.6
KAS PATRIOT	66.2	45.9	56.1	81.4	41.7	61.6
KY 86C-61-8	84.0	48.8	66.4	85.3	50.6	68.0
MADISON	78.9	47.8	63.4	90.1	54.3	72.2
PATTERSON	75.4	48.4	61.9	83.1	45.7	64.4
POCAHONTAS	78.3	37.4	57.9	92.8	35.1	64.0
TERRA SR 204	81.2	48.4	64.8	79.2	46.2	62.7
MEAN	79.6	48.3	64.0	83.3	49.1	66.2
Correlation of Conventional, No-Till, 1998-99: 0.85

 

TABLE 2. LOGAN COUNTY (1998) AND CALDWELL CO. (1999) NO-TILL AND CONVENTIONAL VARIETY TRIAL
	CONV: YIELD (BU/A)			NO-TILL: YIELD (BU/A)
VARIETY	1999	1998	MEAN	1999	1998	MEAN
2540	81.8	58.9	70.4	74.3	46.5	60.4
2552	95.3	41.2	68.3	96.8	41.8	69.3
2568	89.0	45.8	67.4	76.5	34.5	55.5
25R26	91.8	40.3	66.1	78.8	29.3	54.1
AG FOSTER & GAUCHO	83.0	41.1	62.1	100.3	29.7	65.0
AGRIPRO ELKHART	90.5	42.6	66.6	84.5	34.5	59.5
AGRIPRO FOSTER	84.3	36.4	60.4	81.8	26.2	54.0
AGRIPRO MASON	88.0	44.2	66.1	79.8	40.0	59.9
AGRIPRO PATTON	88.5	53.1	70.8	80.8	35.8	58.3
BECK 103	86.3	43.8	65.1	96.8	36.3	66.6
BECKER	80.5	31.2	55.9	79.0	15.6	47.3
CALDWELL	71.5	40.6	56.1	67.8	25.1	46.5
CLARK	67.5	35.8	51.7	60.5	25.4	43.0
COKER 9474	81.5	43.8	62.7	74.5	39.4	57.0
COKER 9663	103.8	48.1	76.0	87.0	46.5	66.8
FFR 522	85.0	35.7	60.4	74.0	32.6	53.3
FFR 555	87.0	26.5	56.8	89.3	21.6	55.5
FFR 558	86.5	43.3	64.9	76.5	28.3	52.4
GLORY	83.3	47.8	65.6	77.8	29.5	53.7
HYTEST W9850	86.3	52.7	69.5	82.3	41.0	61.7
JACKSON	100.3	33.7	67.0	89.8	30.7	60.3
KAS JUSTICE	79.8	56.3	68.1	71.5	38.3	54.9
KAS PATRIOT	93.8	40.0	66.9	89.5	30.3	59.9
KY 86C-61-8	87.0	32.7	59.9	80.3	25.3	52.8
MADISON	90.3	34.1	62.2	78.3	31.2	54.8
PATTERSON	77.8	44.2	61.0	70.0	29.1	49.6
POCAHONTAS	75.3	32.4	53.9	84.3	23.3	53.8
TERRA SR 204	76.3	35.3	55.8	72.0	28.7	50.4
MEAN	85.4	41.5	63.5	80.5	32.0	56.3
Correlation of Conventional, No-Till, 1998-99: 0.74

TABLE 3. CONVENTIONAL VS. NO-TILL, 1998-1999*
VARIETY	1998-99 CONV. YIELD (BU/A)	1998-99  NO-TILL YIELD (BU/AC)
2540	72.4	66.8
2552	75.0	75.8
2568	69.3	64.2
25R26	69.5	63.4
AG FOSTER & GAUCHO	62.2	64.6
AGRIPRO ELKHART	64.4	62.8
AGRIPRO FOSTER	60.8	56.9
AGRIPRO MASON	68.0	63.4
AGRIPRO PATTON	74.7	68.8
BECK 103	62.5	65.1
BECKER	55.1	55.0
CALDWELL	51.9	44.2
CLARK	57.0	52.2
COKER 9474	59.0	58.7
COKER 9663	71.8	71.2
FFR 522	60.6	56.0
FFR 555	59.1	60.5
FFR 558	62.4	58.6
GLORY	68.9	63.5
HYTEST W9850	68.2	65.1
JACKSON	64.7	62.6
KAS JUSTICE	62.0	58.8
KAS PATRIOT	61.5	60.7
KY 86C-61-8	63.1	60.4
MADISON	62.8	63.5
PATTERSON	61.5	57.0
POCAHONTAS	55.9	58.9
TERRA SR 204	60.3	56.5
MEAN	63.7	61.2
Correlation of Conventional, No-Till, 1998-99: 0.88 *1998: Logan and Shelby Co. 1999: Caldwell and Shelby Co.

OBJECTIVE:

Determine whether redistribution of corn residues, relative to the planted wheat row, will improve wheat yields.

METHODS:

Location: Fayette County/Spindletop
Soil Type and Drainage :Maury silt loam - well drained
Previous Crop: Corn
Tillage: No-Tillage (Lilliston 9680)
Cultivar: Pioneer 2552
Planting Date & Rate: Nov. 5, 1998; 26.5 seed/sq.ft.
Harvest Date: June 21, 1999
Fertilizer: Nitrogen - 40 lb N/ac as 34-0-0 on 12/15/98
                                40 lb N/ac as 34-0-0 on 3/2/99
                                80 lb N/ac as 34-0-0 on 4/5/99
Herbicides: Gramoxone Extra - 1 qt/ac on 10/23/98
                    Harmony Extra - 0.7oz/ac on 4/7/99
                    Brominal ME4 - 0.75 pt/ac on 4/7/99
Fungicides:    Tilt 3.2EC - 4 fl oz/ac on 5/15/99
Results: Average of 4 replications - see Table 1, below.
 

CONCLUSIONS:

We removed corn residues prior to seeding wheat and then returned residues inside long "residue bags" at two set-back distances from the row. We had one treatment where we tried to maximize the insulation effect of residue without the chemical alleopathy of compounds leaching from the decomposing residues. We also had several kinds of check treatments (bare, random coverage over the plot without the bag, empty bags placed between the rows). The row spacing was 7 inches.

Yields were among the lowest for treatments where residues were randomly distributed over the wheat rows and placed near the wheat row. The treatment where the residue bag was maintained at some distance from the row during dry weather, and removed during most rainfall events, was among the best treatments. The results suggest that previous crop residues may be both beneficial and detrimental to wheat growth and development.
 
 

TABLE 1. EFFECT OF CORN RESIDUE PLACEMENT ON NO-TILLAGE WHEAT GRAIN YIELD
Residue Placement Treatment	Grain Yield (bu/ac)
Random coverage	46.0 b
Residue bags moved 0.25 inches away	44.9 b
Residue bags moved 1.25 inches away	54.0 ab
Residue bags moved 1.25 inches away & removed before rainfall	61.5 a
Empty residue bag between rows	55.3 ab
Bare (no residue)	53.4 ab

OBJECTIVE:

This study will compliment other studies investigating practices that would best allow for no-till planting of wheat into corn residue. This study continues the comparison of different methods and timing of mechanical shredding of corn stalks of different corn maturities against no shredding and no corn residue.

METHODS:

Corn was planted at the rate of 26,000 seeds/ac using an early season variety (Pioneer 33Y18) and a late variety (Pioneer 3167). The average yields of the corn was bu/ac for the late season and bu/ac for the early season. Both varieties were harvested at 19% moisture and harvest dates were 8-26-98 and 9-8-98 for the early and late corn.

All mechanical shredding was completed immediately after harvest of each corn variety, except for Treatment 9 which was flailed immediately after wheat planting. All residue was removed from Treatment 1, but the plots were not tilled.

Wheat (Pioneer 2540) was planted no-till at the rate of 35 seeds/sq ft. with a 7 inch row spacing. Gramoxone was applied after planting and a total of 120 lbs/ac of N was applied with ½ on Feb. 10 and ½ on March 18. Harmony Extra was applied on March 29 and Tilt on May 3 and Warrior insecticide on Nov. 12 and Dec. 16

TREATMENTS:

1.    Remove all corn residue and plant into clean residue conditions (full season corn).
2.    Plant at an angle into standing harvesting corn stalks (full season corn).
3.    Plant direclty into standing corn residue, not angled (full season corn).
4.    Plant directly into standing corn residue, not angled (full season corn).
5.    Increased wheat seeding rate (15%).
6.    Plant directly into standing corn residue, not angled (early season corn).
7.    Rotary mow corn residue after harvest and plant into mowed residue (full season corn).
8.    Flail mow corn residue after harvest and plant into mowed residue (full season corn).
9.    Flail mow corn residue after harvest and plant into mowed residue (early season corn).
10.  Plant directly into standing harvested corn and flail mow after planting (full season corn).
        Spray UAN on residue at 40 lbs/ac N immediately after harvest.
11.  Flail mow corn residue after harvest and plant into mowed residue (full season corn).
        Apply solid Ammonium Nitrate at 40 lb/ac N after wheat planting.

RESULTS:

The amount of residue cover after planting is shown in Table 1. Only 7% of area was covered when the residue was removed. When the residue was not removed, two treatments resulted in less residue after planting than the other treatments. Planting directly into standing stalks of early maturing corn and spraying 40 lb/ac of N as UAN on full season corn stalks both resulted in less residue after wheat planting. This was probably due to a more decomposition of the corn stalks prior to planting.
 
 

TABLE 1. EFFECT OF RESIDUE MANAGEMENT ON PERCENT OF SOIL COVER AFTER PLANTING WHEAT
Treatment	Corn Maturity	Soil Cover (%)
1. Removed all corn residue	Full	7 a
2. Residue behind combine (as is) diagonally planted	Full	96 c
3. Residue behind combine (as is)	Full	96 c
4. Residue behind combine (as is) 15% increased seed rate	Full	95 c
5. Residue behind combine (as is)	Early	83 b
6. Rotary mowed after harvest	Full	93 bc
7. Flail mowed after harvest	Full	96 c
8. Flail mowed after harvest	Early	97 c
9. Flail mowed after wheat planting	Full	99 c
10. Flail mowed after harvest N sprayed on corn stalks	Full	82 b
11. Flail mowed after harvest N on wheat after planting	Full	95 c

Stands of wheat in the fall are seen in Table 2. The highest stands were in the treatment with a 15% increase in seeding rate and the treatment with all residue removed. The treatment with UAN sprayed on residue after corn harvest resulted in one of the higher wheat stand counts and lowest corn residue covers.

There was no difference between any of the other treatments. So, shredding or not shredding was not an issue as well as early or late maturing corn.

In 1998, flail shredding stands were better than the rotary mowed or planting into standing corn treatments. There was no difference in 1999 and some of this may have been due to excellent stand establishment weather conditions.
 
 
 

TABLE 2. EFFECT OF RESIDUE MANAGEMENT ON WHEAT STAND IN NOVEMBER
Treatment	Corn Maturity	Wheat Stand Plants/sq ft.
1. Removed all corn residue	Full	35.2 ab
2. Residue behind combine (as is) diagonally planted	Full	32.9 bcd
3. Residue behind combine (as is)	Full	34.1 bcd
4. Residue behind combine (as is) 15% increased seed rate	Full	37.8 a
5. Residue behind combine (as is)	Early	31.2 d
6. Rotary mowed after harvest	Full	31.9 bcd
7. Flail mowed after harvest	Full	32.1 bcd
8. Flail mowed after harvest	Full	32.2 bcd
9. Flail mowed after wheat planting	Full	32.6 bcd
10. Flail mowed after harvest N sprayed on corn stalks	Full	34.7 abc
11. Flail mowed after harvest N on wheat after planting	Full	31.3 cd

The warm winter and early spring encouraged high tillering and high amounts of growth on all plots. Unlike last year, there were no visual differences in the treatments during the season. The only exception was where nitrogen was applied in the fall which caused these treatments to have more growth and lodging during the season.
 
 

The yields are found in Table 3 and are very high this year due to favorable weather conditions. Head counts were high in all the treatments due to the warm winter so there was very little correlation between stands and yields. In fact, the treatment where all the residue was removed had one of the highest stand counts but the lowest yield.

The highest yield occurred where the residue was left standing and the wheat was planted at an angle (diagonally) to the old corn rows. Flail mowing treatments also had some of the higher yielding treatments.

Basically, there was little difference between yield. It appears that fall application of nitrogen, as well as removing of the residue, before wheat planting were not helpful.
 

TABLE 3. EFFECT OF RESIDUE MANAGEMENT ON WHEAT YIELDS
Treatment	Corn Maturity	Yield (13.5% H20) (bu/ac)
1. Removed all corn residue	Full	104.6 b
2. Residue behind combine (as is) diagonally planted	Full	118.6 a
3. Residue behind combine (as is)	Full	106.7 ab
4. Residue behind combine (as is) 15% increased seed rate	Full	111.2 ab
5. Residue behind	Early	101.6 b
6. Rotary mowed after harvest	Full	107.9 ab
7. Flail mowed after harvest	Full	112.3 ab
8. Flail mowed after harvest	Early	107.9 ab
9. Flail mowed after wheat planting	Full	112.5 ab
10. Flail mowed after harvest N sprayed on corn stalks	Full	110.7 ab
11. Flail mowed after harvest N on wheat after planting	Full	105.2 b

Doubled-cropped soybeans planted after wheat harvest (Table 4) give some interesting results. All stands were adequate for maximum soybean yields and the differences were relatively small. Planting wheat diagonally across old corn rows resulted in best soybean stands in 1998 but was among the lowest in 1999. Soybean stands behind rotary mowed corn stalks before planting of wheat was low both years so this may not be the best practice concerning double-cropped planting.

The 15% increase in seeding rate also resulted in less double-cropped soybean stands. This practice may increase the planting problems with soybeans.

All other treatments resulted in excellent stands showing little differences over the two years.
 
 

TABLE 4.   EFFECT OF RESIDUE MANAGEMENT ON SOYBEAN STANDS PLANTED AFTER WHEAT HARVEST
Treatment	Corn Maturity	Soybean Stands Plants/Row Ft.
1. Removed all corn residue	Fall	7.35 a
2. Residue behind combine (as is) diagonally planted	Full	6.45 bc
3. Residue behind combine (as is)	Full	7.25 ab
4. Residue behind combine (as is) 15% increased rate	Full	6.45 bc
5. Residue behind combine as is)	Early	6.70 abc
6. Rotary moved after harvest	Full	5.95 c
7. Flail mowed after harvest	Full	6.80 abc
8. Flail mowed after harvest	Early	7.40 a
9. Flail mowed after wheat planting	Full	7.30 ab
10. Flail mowed after harvest, N sprayed on corn stalks	Full	6.55 abc
11. Flail mowed after harvest, N on wheat after planting	Full	7.15 ab

CONCLUSIONS:

There were little differences in stand counts or yields for any of the treatments. Excellent stands were achieved by all methods used. The 15% increased seeding rate treatment and the removing of all of the corn residue gave slightly higher stands but the increase was small and did not result in higher yields.

The favorable winter and spring conditions resulted in excellent tillering and high yields on all treatments in 1999.

The conditions in 1998 were not as favorable and flail shredding of corn was a favored treatment. The experiment results in more helpful information during unfavorable years.

OBJECTIVE:

Determine whether the optimal N fertilizer rate for no-tillage wheat will differ among with N source management or previous crop.

METHODS:

Location: Fayette County/Spindletop
Soil Type and Drainage: Loradale silt loam - well drained
Previous Crops:  Corn or Soybean
Tillage:  No-Tillage (Lilliston 9680)
Cultivar: Pioneer 2540
Planting Date/Rate:  Oct. 25, 1998; 40.3 seed/sq. ft
Harvest Date:   June 30, 1999
Fertilizer: Four Nitrogen Source-Management Schemes
            -urea (46-0-0);
            -ammonium nitrate (34-0-0);
            -urea-ammonium nitrate solution (28-0-0);
                        33% of all N rates on 3/12/99
                        67% of all N rates on 4/12/99

Herbicide: Gramoxone Extra - 1 qt/ac on 10/23/98
Fungicide: Tilt 3.2EC - 4 fl oz/ac on 5/15/99
Results: Average of 4 replications - see Table 1, below.
 

CONCLUSIONS:

Yield was positively influenced by fertilizer N addition and soybean, as opposed to corn, as a previous crop (Table 1). Wheat following soybean averaged 11 bu/ac greater yield than wheat following corn in this study. Averaged across all N rates, and regardless of previous crop, little difference due to N source management was observed. The optimal N rate was little affected by N source management, but was strongly related to the previous crop. The optimal fertilizer N rate was about 27 lb N/ac for wheat following soybean and 81 lb N/ac for wheat following corn. UAN solution application management, whether broadcast or streamjet, had little effect on the yield results for wheat grown in the two rotations.
 
 
 

TABLE 1.   EFFECT OF PREVIOUS CROP, N SOURCE MANAGEMENT, AND N RATE ON YIELD OF NO-TILLAGE WHEAT
		Wheat Yield - by N Source Management
Previous Crop	Fertilizer N Rate lb N/ac	UAN streamjet	Urea broadcast	AN broadcast	UAN broadcast	N Source Average
		--------------------------- bu/ac ---------------------------
Corn	0	49.2	47.6	56.2	46.0	49.8
	30	55.8	60.9	53.0	60.4	57.5
	60	62.1	66.8	57.0	58.7	61.2
	90	60.3	67.2	65.1	64.4	64.3
	120	65.9	60.7	55.5	58.5	60.1
	150	61.1	56.3	63.2	57.3	59.5
	Avg.	59.1	59.9	58.4	57.5	58.7
Soybean	0	66.6	65.6	65.3	65.8	65.8
	30	72.7	73.0	67.3	69.2	70.6
	60	72.9	67.4	68.0	75.8	71.0
	90	71.9	73.7	67.5	72.3	71.4
	120	72.7	71.8	68.9	72.1	71.4
	150	73.3	66.8	68.4	67.4	69.0
	Avg.	71.7	69.7	67.6	70.4	69.9

OBJECTIVE:

Determine whether the soil management system (no-tillage vs. chisel plowing) will influence the fertilizer nitrogen requirement of wheat following full-season soybean.

METHODS:

Location:  Fayette County/Spindletop
Soil Type and Drainage:  Maury silt loam - well drained
Previous Crop:  Soybean
Tillage:  No-Tillage (Lilliston 9680)
            Chisel Plow + Secondary Discing
Cultivar:  Pioneer 25R26
Planting Date/Rate:  Oct. 24, 1998; 40.3 seed/sq ft
Harvest Date:  June 23, 1999
Fertilizer:  Nitrogen - 20% of all N rates on 12/16/98
                                20% of all N rates on 3/2/99
                                60% of all N rates on 4/5/99
Herbicides: Gramoxone Extra - 1 qt/ac on 10/23/98
                    Harmony Extra - 0.7oz/ac on 4/7/99
                    Brominal ME4 - 0.75 pt/ac on 4/7/99
Fungicides: Bayleton 50WP - 4 oz/ac on 5/8/99
                    Tilt 3.2EC - 4 fl oz/ac on 5/15/99
Results: Average of 4 replications - see Table 1, below.
 
 

TABLE 1. EFFECT OF TILLAGE AND FERTILIZER NITROGEN ON WHEAT YIELDS
Fertilizer N Rate (lb N/ac)				Grain Yield (bu/ac)
Fall	Spring	Total		Chisel	No-Tillage
0	0	0		66.5c	67.9c
10	40	50		80.6a	82.8a
20	80	100		79.8a	79.1a
30	120	150		81.3a	73.0b

CONCLUSIONS:

In this, the second year of this experiment, wheat following chisel plowed soybean residues averaged 77.1 bu/ac, while no-till wheat was not significantly different, averaging 75.7 bu/ac. There was a good response (+13.5 bu/ac) to fertilizer nitrogen, with yields increasing with greater fertilizer N rate, up to a total N rate of 50 lb N/ac (40 lb N/ac in the spring). Tillage had little influence on the observed pattern in wheat yield response to fertilizer N. There was some decline in no-tillage wheat yields at the highest N rate, for which no cause was observed.

OBJECTIVE:

Determine whether no-tillage wheat following corn requires an earlier planting date and greater attention to early N nutrition than wheat planted in a tilled seedbed.

METHODS:

Location:  Fayette County/Spindletop
Soil Type and Drainage:  Donerail silt loam - well drained
Previous Crop:  Corn
Tillage:    No-Tillage (Lilliston 9680)
               Chisel Plow + Secondary Disking
Cultivar:  Pioneer 2568
Planting Dates:  Oct. 23, Nov. 5, and Nov. 23, 1998
Seeding Rate:  40.2 seed/sq ft
Harvest Date:  June 30, 1999
Fertilizer:  Nitrogen - 0 and 40 lb N/ac as 34-0-0 on 12/16/98
                                 0 and 40 lb N/ac as 34-0-0 on 3/1/99
                                 80 and 120 lb N/ac as 34-0-0 on 4/7/99
Herbicides:  Gramoxone Extra - 1 qt/ac on 10/23/98
                    Harmony Extra - 0.7 oz/ac on 4/7/99
                    Brominal ME4 - 0.75 pt/ac 4/7/99
Fungicides:    Bayleton 50WP - 4 oz/ac on 5/8/99
                    Tilt 3.2 EC - 4 ft oz/ac on 5/15/99
Results:        Average of 4 replications - see Table 1, below.
 

CONCLUSIONS:

Stand establishment was excellent at the first two planting dates, but was weaker at the last date (data not shown). There was a planting date by tillage interaction, with no-till wheat yielding less than chisel plow wheat at the first planting date, but there was no difference between tillage systems at the later two dates (Table 1). Again, no-till wheat was not inferior with later planting.

Nitrogen timing treatments did not interact with planting date or tillage treatments. Fall application of N slightly improved yields (+4 bu/ac), while none of the spring N management alternatives affected yield.
 
 

TABLE 1. EFFECT OF PLANTING DATE, TILLAGE AND N TIMING ON WHEAT GRAIN YIELDS
Planting Date	Tillage System	Fall N Rate	Early Spring N lb N/ac	Late Spring N	Grain Yield bu/ac
PLANTING DATE BY TILLAGE INTERACTION
Oct. 23	NT	-	-	-	73.5
	CH	-	-	-	80.6
Nov. 5	NT	-	-	-	67.0
	CH	-	-	-	69.1
Nov. 23	NT	-	-	-	48.1
	CH	-	-	-	48.0
MAIN EFFECT OF FALL N RATE
-	-	0	-	-	66.2
-	-	40	-	-	62.5
MAIN EFFECT OF EARLY SPRING N RATE
-	-	-	0	-	64.1
-	-	-	40	-	64.7
MAIN EFFECT OF LATE SPRING N RATE
-	-	-	-	80	64.3
-	-	-	-	120	64.5

OBJECTIVE:

Evaluate the effect of different seeding rates and established stand on the yield potential of wheat.

METHODS:

The experiment was established in Caldwell County on a tract of land near the UKREC Center in the Fall of 1998. The wheat variety, Pioneer 2540, was planted on October 12, 1998 with a Lilliston 9670 no-till drill (7-inch row spacing) in both a conventionally tilled (chisel plow, 2 diskings, roterra) and no-till seedbed. The previous crop was corn and the corn residue was flail mowed prior to tillage and planting. Roundup Ultra (3 qts/A) was applied to the no-till area after planting on 10-12-98. All treatments received the following: Harmony Extra herbicide (0.5 oz/A) on 3-28-99; Warrior insecticide (3 oz/A) on 11-12-98 and 12-15-98; and Tilt fungicide (4 oz/A) at heading. Fertilizer (200 lbs. of 18-46-0 per acre and 100 lbs of 0-0-60 per acre) was applied to the study area on 10-1-98. A total of 100 lbs of N/acre as ammonium nitrate was applied in the spring in a split application (40 lbs on 2-22-99 and 60 lbs on 3-18-99).

Four wheat seeding rate treatment/goals were compared: 45, 35, 25 and 15 seeds/ft^2. The drill was calibrated for each seeding rate treatment to insure seeding rate accuracy and to establish drill settings that would deliver the amount of seed needed in close proximity to the seeding rate treatment goals. Seeding rates were adjusted for germination so that wheat plant establishment would be numerically close to the seeding rate treatment goals. Seeding rate treatments were the same for both wheat tillage planting systems (conventional and no-till). Wheat data was collected on: fall stand counts (10-27-98), spring head counts (5-27-99), lodging (6-15-99), and yield (6-16-99).
 

RESULTS:

The wheat seeding rate study results are shown in Table 1. Excellent stand establishment was achieved at all seeding rates in both tillage systems. The % stand achieved (Column 3), based on the actual number of seeds drilled (Column 1) and fall plant stands achieved (Column 2), was over 80% for all seeding rate treatments which is considered good. The lowest seeding rate treatment (15 seeds/ft²) achieved the highest % stand (>90%) and the highest seeding rate treatment (45 seeds/ft²) achieved the lowest % stand. The actual plant stands achieved (Column 2) were numerically very close to the seeding rate treatment goals and is attributed to the adjustment of seeding rates for germination (Column 1) and also excellent planting conditions in the fall of 1998. The final plant stands achieved were very similar for both tillage systems at each seeding rate (Column 2). Because the final plant stands were very similar for both tillage systems within each seeding rate, this provided an excellent opportunity to compare the influence of tillage system on wheat yield potential when plant stands are equivalent. Normally, the no-till planting system results in a comparatively lower plant stand establishment of at least 2-3 plants/ft² (or more) than the tillage planting system at equivalent seeding rates.

Total wheat head numbers (Column 4) were greater at the higher seeding rates. However, even at the lowest seeding rate, total heads/ft² were sufficient for optimum wheat yield potential (considered to be > 60 heads/ft²). At the lower seeding rates, the wheat plant compensated for the thinner stands by developing more tillers and heads per plant (Column 5). Wheat heads per plant were calculated from heads/ft² (Column 4) and plants/ft² (Column 2) within each seeding rate treatment. The total number of heads (Column 4) were quite similar for both tillage systems within each seeding rate. However, there was a trend for more total heads in the no-till system at the higher seeding rates.

Severe wind and rain storms in late May caused the wheat to lodge (Column 6). The variety used, Pioneer 2540, also has a tendency to lodge. Lodging increased as seeding rate increased. The greatest lodging occurred at the highest seeding rate; however, some lodging occurred even at the lowest seeding rate. Tillage system did not seem to have an effect on lodging potential. There was no correlation between the amount of lodging and yield level which indicated that lodging occurred late enough so that it did not affect yield potential. Probably the greatest yield reducing factor of lodged wheat comes from harvest loss. However, the wheat in this study was carefully harvested so that harvest loss was not a factor.

Excellent wheat yields were achieved at all seeding rates (Column 7). In the no-till system, there was no significant difference in yield among the four seeding rates. Similarly, yields were equivalent in the conventional tillage system for all four seeding rates except for a slight yield reduction at the highest seeding rate. The results were somewhat surprising since it was expected the lowest seeding rate (15 seeds/ft²) would result in a yield reduction. However, it was apparent that more head bearing tillers were produced per plant to compensate for the thinner plant stands. There was also no difference in yield between the two tillage systems.

CONCLUSIONS:

The low seeding rate/final stand (15/ft²) produced yields equal to higher seeding rate/final stands (25-45/ft²). This does not imply that these low wheat seeding rates should be utilized and that similar results would be obtained. This is only one-year's results with one variety from one location. Two other factors need to be considered. The variety used in this study (Pioneer 2540) has excellent tillering capacity. Other varieties with low tillering capacity may not perform as well at low seeding rates. Also, the 1998-99 growing season was excellent for fall growth and tiller development, winter survival, and spring growth. Whereas, adverse growing seasons would hinder plant growth and development and thinner stands would not perform as well.

The no-till wheat system had the same yield level and potential as the conventional tillage wheat system when final plant stands were equivalent.
 
 

OBJECTIVE:

Survey wheat fields to assess possible relationships between Fusarium head blight (FHB) and various independent variables, including: level of corn residue in the fall, wheat variety, planting date, crop head density, and crop stage and date when FHB was rated.

METHODS:

One hundred wheat fields, representing 16 counties and four states, were selected for scouting (Table 1). Fields surveyed were those already under contract with either Opti-Crop or Wheat Tech. Each group was responsible for scouting 50 fields. Data recorded from each field in the fall included County and State, planting date, variety, and percent residue cover. Residue cover was determined using a standardized procedure recognized by NRCS. Fields which were not in corn prior to wheat being planted were recorded as having zero corn residue. In the spring, starting around the late milk stage of crop development, 25 heads were collected from four locations in each field surveyed. Individual heads were then assessed for the severity of FHB. Consistency among the various scouts rating FHB was achieved using a pictorial disease rating aid developed at North Dakota State University. Other field data recorded included: stage of plants when rated, rating date and head density. Data were subjected to SAS analysis of variance as well linear regression analysis, where appropriate.

RESULTS:

Nine survey fields were lost in the spring due to low prices. Thus, data were only collected for 91 of the 100 original fields. Overall, FHB incidence and severity across the 91 fields surveyed were low and moderate, respectively (Table 2). Average field severity for FHB, which is a fairly good indicator of maximum yield lost due to FHB, was 2.7% across all fields surveyed. The fields surveyed represented 25 different soft red winter wheat varieties. The three most commonly encountered varieties were Pioneer 2552 (20 fields), Pioneer 2545 (11 fields) and Pioneer 25R26 (9 fields). The overall incidence and severity of FHB in these varieties were similar. Other varieties were represented by five or fewer fields.

Various independent variables were significantly related to FHB incidence, severity, and/or field severity in 1998-99 (Table 3). For example, corn surface residue in the fall had a highly significant relationship with both FHB incidence and field severity. However, very low r² values (0.17 and 0.11, respectively) indicate extensive variability exists in the relationships. This suggests that other factors, such as weather, are much more influential than corn surface residue in the development of local FHB epidemics when disease pressure is low. The same situation was found to exist during the 1997-98 survey when disease pressure was moderate.

Similarly, rating date was significant for FHB incidence, severity and field severity, but r² values were extremely low (i.e., r²<0.1). There was a significant relationship between head density and field severity, and plant stage was significantly related to severity. However, in both these instances r² values were very poor, so very little should be made of the associations. Planting date was not significantly associated with FHB in either survey year.
 

TABLE 1. LOCATIONS OF WHEAT FIELDS SURVEYED FOR  FUSARIUM HEAD BLIGHT (FHB) DURING 1998-99.
STATE	COUNTY	NO. FIELDS
Indiana	Perry	6
	Posey	5
	Spencer	10
	Warrick	1
Kentucky	Christian	7
	Daviess	8
	Hancock	2
	Henderson	4
	Logan	17
	Simpson	5
	Todd	10
	Trigg	2
	Warren	3
Missouri	Dunklin	2
	Scott	3
Tennessee	Robertson	6
TOTAL SURVEYED 91* *Nine survey fields were lost because of low prices.

                                                                        Ave % FHB             Ave % FHB             Ave % FHB
Variable                                     N                 Incidence (SE)             Severity (SE)          Field severity

Area/State     Mammoth Cave     23                     12.0 (2.1)                 26.3 (3.1)                 3.7 (0.8)

                      Pennyrile               19                     10.8 (2.3)                 24.8 (3.3)                 3.2 (0.8)

                      Green River           13                      7.5 (2.3)                 11.5 (2.1)                 1.6 (0.6)

                      Tennessee               6                     15.7 (4.7)                 15.4 (2.8)                 2.6 (0.9)

                      Indiana                  23                       8.9 (1.6)                 31.9 (4.0)                 2.8 (0.5)

                      Missouri                  5                       3.2 (1.0)                 49.7 (13.5)               2.1 (0.7)

Variety          Pioneer 2552          20                   14.3 (1.7)                   21.1 (2.8)                 3.0 (0.5)

                     Pioneer 2545          11                   11.0 (3.1)                   30.3 (3.7)                 3.2 (0.9)

                     Pioneer 25R26         9                     9.0 (3.0)                   21.6 (4.7)                 3.0 (1.1)

                     Becker                     5                   14.6 (5.4)                   46.9 (9.3)                 6.2 (2.7)

                     Patterson                  5                   10.0 (5.0)                  19.9 (5.6)                  1.5 (0.6)

                     Pioneer 2568            4                  12.0 (3.9)                   34.1 (10.1)                5.1 (2.3)

                     Coker 9663              4                   21.8 (7.1)                  27.2 (5.6)                  5.3 (1.6)

                     Pioneer 25R57          4                     3.3 (0.5)                  30.1 (5.4)                  0.9 (0.2)

                     Pioneer 2540            4                     7.5 (2.7)                  30.9 (14.9)                2.7 (1.1)

                     Justice                      3                     8.7 (7.7)                   22.1 (14.0)                0.9 (0.7)

                     Madison                   3                     4.3 (3.0)                  11.7 (5.9)                   0.8 (0.6)

                     Clark                        2                   19.0 (17.0)                22.7 (5.8)                   3.3 (2.8)

                     Coker 9474              2                     1.5 (0.5)                   7.0 (1.1)                    0.1 (0.1)

                     Esther                       2                   12.5 (1.5)                 52.4 (6.3)                       .6 (1.6)

                     LG 1155                   2                    3.5 (1.5)                 15.3 (8.3)                     0.7 (0.5)

                     Pioneer 2510             2                   1.0 (1.0)                   3.5 (2.5)                      0.1 (0.1)

                    Cardinal                      1                   0.0                           0.0                               0.0

                    FFR 558                     1                   2.0                           7.0                               0.2

                    LG 1388                     1                   13.0                       33.5                               4.4

                    LG 1433                     1                     3.0                       66.8                               2.0

                   Ruth                             1                     1.0                        7.0                                0.1

                   SW 315                       1                     1.0                      14.0                                0.1

                   Pioneer 2580               1                     6.0                      78.8                                 4.7

                   Pioneer 2684               1                     3.0                      20.3                                 0.6

                   Quantum EH  9723      1                   22.0                      44.5                                 9.8
 

Incidence = Percent of heads with any FHB; Severity = Percent surface area of heads with FHB, but only of diseased heads. Field severity = Percent surface area diseased of all heads (i.e., estimates maximum yield lost due to FHB). SE = Standard Error
 

TABLE 3. RELATIONSHIPS BETWEEN FUSARIUM HEAD BLIGHT (FHB) INCIDENCE1, SEVERITY2, AND FIELD SEVERITY3 AND VARIOUS DEPENDENT VARIABLES FROM 91 WHEAT FIELDS EVALUATED DURING 1998-99.
----------------------------------X VARIABLE------------------------------------
Y Variable	% Surface Corn Residue (Fall)	Planting Date	Head Density (Plants/Ft2)	Rating Date	Plant Stage when Rated for FHB
FHB Incidence	0.0001 (0.17)4	NS	NS	0.0002 (0.09)	NS
FHB Severity	NS	NS	NS	0.02 (0.3)	0.01 (0.05)
FHB Field Serv.	0.001 (0.11)	NS	0.03 (0.03)	0.0003 (0.06)	NS
1 Incidence is percent of heads with any FHB. 2 Severity is the surface area affected of diseased heads only. 3 Field severity is average surface area affected across all heads evaluated (i.e., diseased and non-diseased). 4 P value (r2); NS = P>0.05

CONCLUSION:

For the second consecutive year, the level of corn residue which exits in a field in the fall has been shown to be significantly related to FHB. However, in both years, the relationship was highly variable. This suggests that other factors are more important than corn residue in determining the incidence and severity of FHB, locally. A third year of survey data is needed before a definitive conclusion can be made regarding the corn residue/FHB relationship. Of the variables planting date, variety and head density, only head density (an indicator or crop density/yield potential) may also play a role, albeit a minor role based on data from both survey years. Apparently there are other very important factors which are heavily impacting FHB development which are not being picked up by the survey. Environmental conditions impact numerous aspects of FHB epidemiology, and are probably playing a dominant role. For example, environment has an impact on Fusarium spore production, release, and movement to wheat; spore survival and infection; and the extent of FHB expansion in heads following infection.

OBJECTIVES:

• To identify resistance to FHB in greenhouse and field screening trials.
• To evaluate apparent vs. actual FHB infection by plating out seeds on selective media.

Entries in the 1999 Uniform Winter Scab Nursery along with a number of advanced breeding lines were planted in the field in a randomized complete block design with four replications on 29 October 1998. Each plot consisted of a single 4ft. row. The previous crop was corn and the seedbed had been chisel plowed and disked. Entries in the greenhouse were planted in a completely randomized design with a variable number of replications.

Mason jars containing approximately 500 g of autoclaved corn seed were inoculated with the head scab fungus F. graminearum on April 5, 1999. On April 27, wheat plots were inoculated just prior to heading by spreading 35-40g of the inoculated corn mixture per plot. Plots were mist irrigated daily beginning May 7 for approximately one hour during the early part of the morning, mid-day, and late evening throughout anthesis into early grain fill. Because of extremely dry weather and a delay in irrigation, wheat plots were inoculated a second time with more corn inoculum on May 17. Incidence of scab was reported as the percentage of scab-infected heads per total number of heads per row. Severity was determined by counting the number of infected spikelets and dividing by the total number of spikelets on diseased heads only.

Several advanced breeding lines were evaluated in the greenhouse for Type I (preventing initial infection) and Type II (reducing spread within the head) resistance.

To measure Type II resistance, at flowering, 3 l containing approximately 1,200 spores was injected into a single floret in the middle of the head. After inoculation, plants were placed directly into humidity chambers for three consecutive nights. The final percentage of infected spikelets per spike was recorded on day 21. Type I resistance was measured by spraying a spore suspension onto heads at flowering, and placing the pot in a humidity chamber for 3 nights. Twenty-one days after inoculation plants were rated for disease development using a 0-4 scale: 0 = no disease, 1 = 1-25%, 2 = 26-50%, 3 = 51-75%, and 4 = 76-100% of spikelets infected.

Wheat seed was collected from both injection and spray test entries. Total seed number plus the number of visually scabby seed were recorded for each seed lot. Plates were incubated for 7-10 days at 20 C. Each plate was visually inspected for F. graminearum contaminated seed. Seed from the injection test was also assessed for the presence of F. graminearum. In this particular test, seed was visually inspected and placed in the following three categories according to appearance: l) normal, 2) small, wrinkled and 3) tombstone. The location and category of each seed was recorded on the top of each petri plate. After incubation, those seed that were positive for the presence of F. graminearum were recorded.
 

RESULTS AND DISCUSSION:

For the first time in three years of field screening, incidence and severity in our inoculated, irrigated nursery were rather low (Table 1). Nonetheless, the resistant checks, Ernie and Freedom actually showed some signs of resistance in our nursery, which was not the case in the previous two years. Thus, the scab pressure that we observed this year may have been closer to what would be expected under a natural infection.

Even with a large number of replications (15 plants), repeatability of assessment of type II resistance was low (Table 2). The most promising entry, KY 91C-022-36, ranged from 6 to 26% scabby spikelets. With only three plants, however, it is difficult to have confidence in this estimate.

We tend to regard an evaluation of scabby seed after harvest as a confirmation of our assessment of scab on the intact spike. Although visual assessment of seed seems straightforward, plating out the seed on a selective medium revealed some surprises (Tables 3, 4). Seed of Freedom, for example, was visually rated at 17 % scabby, yet plating the seed revealed that 82% was actually infected with F. graminearum.
 
 
 

TABLE 1. UNIFORM WINTER WHEAT SCAB SCREENING NURSERY, LEXINGTON, KY
	Average	Average				Heading	DON
	Severity	Incidence	FHB	Height	Yield	Date	Levels
Cultivar	%	%	Index	(in)	(bu/a)	(Julian)	(ppm)
NY87048-7387	1.75	0.65	0.46	40	61.25	134	0.60
Ernie	3.50	1.34	0.09	32	57.82	125	0.78
IL94-1909	4.38	0.68	0.06	41	89.05	129	0.55
OH 544	6.42	1.10	0.10	41	93.68	134	0.55
NY86003-106	8.50	1.75	0.19	37	71.89	133	0.80
M94-1069	11.13	5.63	0.91	35	75.49	128	0.20
Freedom	15.95	4.11	0.72	35	77.90	129	0.63
Geneva	17.08	5.02	1.71	36	56.62	131	0.93
OH 522	17.19	9.92	1.88	35	93.51	127	0.80
NY6003-27	18.79	4.50	2.23	41	68.29	132	1.88
Foster	19.25	2.18	0.93	36	77.90	128	0.50
2545	22.95	9.02	2.00	35	57.99	132	1.70
OH 657	23.38	3.55	1.03	41	80.64	132	0.65
IL96-24078	27.08	1.73	0.49	34	63.48	126	0.75
NY87048W-7405	27.08	8.16	0.98	34	66.23	129	1.00
P92823A1	27.50	5.39	2.58	35	91.28	128	0.55
VA96-54-216	29.45	8.63	2.68	33	102.60	126	0.45
Goldfield	30.21	2.36	0.88	38	107.75	129	0.33
OH 609	30.40	4.98	1.63	36	97.11	127	0.33
Cayuga	31.48	3.97	1.72	42	78.75	135	1.00
Patterson	33.25	5.92	2.15	38	82.36	126	0.88
P88288C1	34.49	7.57	2.94	34	72.23	129	0.55
VA96W-348	38.71	15.27	5.75	32	71.72	127	0.90
M95-3349	43.13	3.15	1.11	37	109.12	128	0.53
IL95-4162	47.50	2.74	1.26	37	101.06	127	0.48
P86958RC2	47.54	3.92	2.35	36	81.33	129	0.95
KY89-895-14	51.20	11.51	5.78	34	88.88	129	0.58
Roane	53.45	18.44	10.06	33	81.84	126	2.38
Location Mean	16.68	4.27	1.06	37	82.29	130	0.80
L.S.D.	21.90	4.24	2.06	2.00	23.63	1.35	0.62
C.V.	71.90	65.99	89.81	4.69	24.91	0.89	59.20

 
 

TABLE 2. EVALUATION OF FOURTEEN ADVANCED BREEDING LINES IN THE GREENHOUSE FOR TYPE II^A RESISTANCE TO SCAB.
 

AUDPCb

% Diseased spikeletsc

Entry	N	Min	Max	Mean		Min	Max	Mean
91C-092-3	5	0.7	2.3	1.7		6	32	22
91C-092-5	12	0.5	6.5	1.6		5	100	18
91C-092-7	3	0.7	2.8	1.9		6	36	16
91C-092-72	14	0.1	9.1	3.9		5	100	53
91C-092-105	6	0.7	8.2	3.9		7	100	37
91C-092-111	3	1.2	5.3	4.5		17	94	48
91C-019-17	4	0.6	3.2	2.9		5	39	24
91C-022-34	4	0.7	3.2	2.1		6	41	16
91C-022-36	3	0.3	2.5	2.2		6	26	17
91C-022-42	4	0.3	5.0	4.2		6	100	53
91C-046-2	4	0.9	4.9	4.4		7	64	43
91C-261-13	6	0.2	3.4	2.6		5	100	35
91C-261-24	15	0.7	8.8	3.3		6	100	46
92C-432-62	14	0.7	7.4	3.3		6	100	46

^aReduction of spread within the spike.
^bArea under the disease progress curve.
^cPercent of infected spikelets per spike recorded 21 days after injection.
 
 
 

TABLE 3. MEAN NUMBER OF SEED COLLECTED AND PERCENT OF SEED INFECTED WITH F.graminearum FROM FOURTEEN ADVANCED BREEDING LINES SCREENED IN THE GREENHOUSE FOR TYPE II RESISTANCE TO SCAB.
	Mean number of seeda		Percentage of infected seed

Entry	Normal	Small/  Wrinkled	Tombstone		Normal	Small/  Wrinkled	Tombstone
91C-092-3	32.8	3.8	4.2		5.7	7.7	41.7
91C-092-5	26.6	3.6	1.5		0.3	1.6	33.3
91C-092-7	18.3	0	0		0	0	0
91C-092-72	15.2	15.4	5.5		5.2	14.8	26.1
91C-092-105	15.8	5.5	2.8		5.7	12.2	47.0
91C-092-111	1.0	24.3	7.3		0	3.0	34.2
91C-019-17	24.5	0	4.3		1.8	0	61.9
91C-022-34	12.5	14.3	0.3		4.4	0	0
91C-022-36	8.8	19.6	4.4		2.3	1.0	30.5
91C-022-42	18.8	3.0	3.0		1.0	0	12.5
91C-046-2	12.8	9.0	1.8		0	7.4	11.1
91C-261-13	15.2	5.0	3.1		15.4	7.2	48.4
91C-261-24	10.2	8.3	9.2		9.2	10.2	33.4
92C-432-62	12.0	5.4	2.9		5.1	13.9	50.3

^a Visual assessment of seed by appearance.
^b Percent of F. graminearum contaminated seed per total number of seed by category, recorded 7-10 days after plating on selective media.
 

TABLE 4. EVALUATION OF FIFTEEN ADVANCED BREEDING LINES SCREENED IN THE GREENHOUSE FOR TYPE I RESISTANCE TO SCAB.
Entry	N	Disease Scorea	Total Seed	Percent  Visual  scabby seedb	Percent of seed infected with  F. graminearumc
Glory	3	2.7	19	77	87
KAS EX 108	1	4	6	100	83
FFR 555	5	3.6	21.2	66	70
Foster+Gaucho	4	2.8	16.3	40	92
2552	3	1.7	13.3	34	76
KY 89C-744-44	3	2.3	19.3	37	60
92C-432-62	3	0.3	13	30	18
92C-433-77	1	1	32	19	72
91C-261-3	5	1.2	38.2	15	43
91C-261-3	3	2.7	3	99	100
90C-383-18	1	1	27	100	81
91C-260-6	3	0.7	34.6	6	15
91C271-74	3	1.7	18	51	53
Freedom	2	2	29	17	82
Ernie	3	1	13.4	25	17

^aTwenty-one days after inoculation plants were rated for disease development using a 0-4 scale:
0 = no disease, 1 = 0-25%, 2 = 26-50%, 3 = 51-75%, and 4 = 76-100% of spikelets infected.
^bVisual assessment of seed by appearance.
^c Percent of F. graminearum contaminated seed per total number of seed, recorded 7-10 days after plating on selective media.

OBJECTIVE:

To evaluate the role of various foliar fungicide treatments in the management of Fusarium head blight (FHB). The effort is part of a "uniform" test being administered by the National Fusarium Head Blight Initiative.

METHODS:

The test was established at the Research and Education Center in Princeton, Caldwell County, Kentucky and on the Larry Thompson Farm, located near Keysburg, Logan County, Kentucky. Both test locations were in corn during 1998. In Princeton, a reduced till seedbed was prepared by discing the soil/corn stubble three times prior to seeding wheat. In Keysburg, the corn stalks were mowed and wheat was planted no-till. Seed of the soft red winter wheat varieties Patterson and Becker were planted at Princeton (October 14, 1998) and Keysburg (October 13, 1998), respectively. At Princeton, the seeding rate used was 35 seed/ft². In Keysburg, a higher seeding rate of 47 seed/ft² was used to compensate for planting into a non-tilled seedbed. Fungicide treatments were the same for both locations and these are indicated in the data tables along with the specific dates and crop stages at the time of application. Fungicides were applied with CO²-pressurized backpack sprayers delivering 20 gpa at 40 psi (Princeton) and 15 gpa at 35 psi (Keysburg); at both locations, fungicides were delivered via spray booms fitted with flat-fan nozzles. Treatments were replicated four times and were arranged following a randomized complete block design. In Princeton, plots were 4-ft -wide x 10-ft-long. In Keysburg, plots were 5-ft-wide x 15-ft-long. No insecticides or herbicides were applied to the Princeton test, but the herbicide Harmony extra and the insecticide Warrior were applied on March 31 to the Keysburg test; a second application of Warrior was made on May 2. In Princeton, nitrogen fertility was a split application of 35 lbs actual N per acre applied on February 19, 1999, followed by 70 lbs actual N applied on March 19. In Keysburg, 35 lbs of actual N per acre were applied on February 23, followed by 70 lbs actual N on March 22. Entire plots (Princeton) or plots trimmed to 14 ft (Keysburg) were harvested on June 15 using a Hege small plot combine; seed yields were calculated based on a moisture of 13.5%. Foliar disease ratings were made by D. Hershman at both locations during just prior to the soft dough stage of grain development. FHB was rated by evaluating 100 consecutive heads in the center row and middle of each plot. FHB severity was estimated, visually, as percent surface area affected.
 

RESULTS:

FHB levels were very low at both test locations. FHB incidence ranged from 1.5% - 2.5% at Princeton and 1.5% - 3.5% at Keysburg. There were no significant differences among any of the treatments in regards to FHB incidence, severity, or field severity. Extremely low FHB pressure probably existed because of an extended period of dry, low humidity conditions which existed while tests test crops were flowering in May. Overall, the prevalence of other diseases remained low at Princeton (data not presented), but there was slightly more leaf rust on the flag leaves in the check plots compared with other treatments. Nonetheless, there were no significant differences among treatments in terms of treatment yield or test weight. Plot yields were probably reduced somewhat across the Princeton study slightly due to a general infection of plots by barley yellow dwarf virus. At Keysburg, late-season disease pressure was significant. However, the fact that no significant differences were detected among treatment yields (which were very high), test weights, or foliar disease (data not presented) suggest that late-season disease was of little importance in the test.
 

CONCLUSION:

FHB levels were not sufficient to permit evaluation of the fungicide treatments against FHB.
 

                                                                                      % Fusarium Head Blight¹

Treatment and rate*        Timing of app.**                 Inc         Sev    Field sev         (bu/A)          (lbs/bu)

Non-treated                             --                                 2.3         49.3         0.8                 79.8             57.6

Folicur 3.6F, 6.0 fl oz +
Induce 0.06% v/v                     10.51                           1.8         40.8         0.8                 80.1             56.8

Folicur 3.6F, 4.0 fl oz+
Induce 0.06% v/v                     10.51                           1.8         37.0         0.9                 81.8             57.1

Benlate 50SP, 0.5 lb+
Manzate 200, 1.0 lb+
DPX adjuvant, 0.25% v/v         10.51                           1.8         47.5         0.7                 76.8             57.1

BAS 500 00F, 15.4 fl oz+
Agridex 1.0% v/v                      10.3                             1.8         55.5         0.7                 83.4             57.9

BAS 500 00F, 15.4 fl oz+
Agridex 1.0 v/v                         10.51                           2.5        58.0         0.7                  74.6            57.4

Stratego 2.1E, 10.0 fl oz           10.51                           2.0         47.3         0.9                 74.7            56.1

Stratego 2.1E, 14.0 fl oz           10.51                           1.5         23.8         0.6                 77.4             57.1

Quadris 2.08SC, 12.3 fl oz       10.51                           3.3         58.8         1.8                 84.9             57.1

Quadris 2.08SC, 9.2 fl oz         10.51                           1.8         51.8         1.0                 77.2             56.8

                                                                             % Fusarium Head Blight                Yield           Tst. Wt.
Treatment and rate*   Timing of app.**          Inc.         Sev.       Field ser             (bu/ac)          (lbs/bu.)

Non-treated                                -                       1.5        60.0            0.6                     97.6        55.8

Folicur 3.6F, 6.0 fl oz +
Induce 0.06% v/v                    10.51                    2.3        62.0            0.4                    96.2        56.1

Folicur 3.6F, 4.0 fl oz +
Induce 0.06% v/v                   10.51                     2.0        38.5            0.4                    95.7        55.1

Benlate 50SP, 0.5 lb +
Manzate 200, 1.0 lb +
DPX adjuvant, 0.25% v/v       10.51                    3.0        45.5            0.5                    96.7        55.4

BAS 500 00F, 15.4 fl oz +
Agridex 1.0% v/v                   10.3                      3.0        37.5            0.4                    96.7        55.9

BAS 500 00F, 15.4 fl oz +
Agridex 1.0% v/v                   10.51                    2.5        54.5            0.6                    98.7        56.3

Stratego 2.1E, 10.0 fl oz        10.51                    2.8        47.0            0.5                    97.0        54.8

Stratego 2.1E, 14.0 fl oz        10.51                    3.0        53.5            0.5                    96.8        55.3

Quadris 2.08 SC, 12.3 fl oz   10.51                    3.0        48.8            0.5                    92.0        55.3

Quadris 2.08 SC, 9.2 fl oz     10.51                    3.5        46.8            0.5                    94.1        54.9

                                        Treatment Prob (F)             0.1         0.6             0.6                     0.9         0.1

ACKNOWLEDGMENT:

Various individuals worked on this study and their assistance is greatly appreciated. They are: Charles Tutt, Michael Forsythe, Debbie Morgan, John James, and Dottie Call.

OBJECTIVE:

To evaluate the role of various seed treatment fungicides (also a fungicide/insecticide combination) in wheat production in Kentucky.
 

METHODS:

The experiment was established on the Trevor Gilkey farm adjacent to the University of Kentucky Research and Education Center in Princeton, Caldwell County, Kentucky. The test site was in corn during 1998 and the seedbed was disced three times in preparation for planting wheat. Seed of the soft red winter wheat variety, Wakefield, which had been treated with various seed treatments by Gustafson, Inc., was planted on October 14, 1998. Seed was intentionally planted at a low seeding rate of 28 seed/ft² to test the value of treatments in a situation where tiller production and survival is critical to the success of the crop. Treatments were replicated four times and were arranged following a randomized complete block design. Plots were 6-rows-wide (7-in spacing; 4 ft.) X 10-ft -long. No insecticides of herbicides were applied to plots. Nitrogen fertility was a split application of 35 lbs actual N applied on February 19, 1999 followed by 70 lbs actual N applied on March 19. Stand counts were taken in the fall, approximately two weeks after seeding. Head counts and disease ratings were made and the dates are indicated in the table. Tilt 4E (4 fl. oz./A) was applied to all plots at Feeke's stage 10.3 (mid-heading) to protect plots from late-season diseases. Plots were harvested on June 15 using a Hege small plot combine. Seed yields were determined in the laboratory and were based on a moisture content of 13.5% and 60 lb/bu test weight.
 

RESULTS:

Unseasonably mild fall and winter conditions were very favorable for seed germination, plant establishment, tiller production, and tiller survival. Consequently, fall stand counts and spring head counts were similar among but one treatment. That treatment was LS249 which had significantly fewer heads than the check plots. BYD was fairly extensive in the plot area, but none of the treatments had less BYD than the control. The failure of Gaucho 480 to provide control of BYD, and our observations of other fields and plots, suggest that infection by BYDV occurred during the period late fall to early spring. This is a period when Gaucho is likely to have lost most of its activity. Speckled leaf blotch (Septoria tritici) was the only fungal disease which was highly active in plots, and this was mostly during April and very early May. Dry weather and Tilt application limited the development of that disease on flag leaves in plots and those leaves were not rated for disease. F-1 and F-2 leaves were rated. No treatment had less speckled leaf blotch on the F-1 leaves compared to the check, but the treatments with either Raxil-Thiram or Dividend had significantly less disease on the F-2 leaves. No significant difference were detected in yield or test weight among the different treatments. Overall, plots yields were good, but test weights were on the low side. This is likely due to the BYDV infections. Fusarium head blight was not a factor in this test. Neither were any other pests.
 

CONCLUSION:

Seed treatments are of no measurable economic benefit when high quality seed are planted into a favorable seedbed, and good growing conditions (with concomitant low disease pressure) persist throughout the fall, winter and spring. This study indicates that this is true even when an artificially low seeding rate is used. Of course, there would be a lower seed rate limit where yields would be affected, but determining this lower limit was not the intent of this study. Data indicate that certain seed treatments can reduce the severity of speckled leaf blotch, but yield differences may not be evident if disease pressure is mid- to late-season disease is light (naturally or by the use of foliar fungicides). These results are consistent with the results of other studies over the last 10 years.
 

                                                                                                       Speckled leaf blotch+       Yield             Tst.wt.
Treatment and rate/cwt    Plants/ft²*     Heads/ft²** %BYD#             F-1         F-2        Bu/A             lbs/bu

Non-treated                             21.5              77.1                 23.8        6.7         68.6             82.0           54.1
 

Raxil-Thiram 3.5 fl.oz.              23.2              66.6                 33.8        6.1       46.9             84.8           54.4
 

Raxil XT 0.16 fl.oz.                 24.3               68.3                 28.8         6.9         59.5             87.4            54.9

LS249 5.0 fl.oz.                      26.8             58.9                 26.3         7.7         67.8             84.1            54.4
 

LS176 0.08 fl.oz.+
Allegiance 0.1 fl.oz.                 23.4             72.3                  38.8          9.2         67.2             85.1            54.9
 

LS176 0.32 fl.oz.+
Allegiance 0.1 fl.oz.                 22.4             71.5                  36.3          4.2         57.4              81.7           55.0
 

Dividend XL 1.0 fl.oz.             21.9             65.5                  16.3          3.6       47.1              87.0             54.8
 

Raxil-Thiram 3.5 fl.oz.+
Gaucho 480 1.0 fl.oz.             22.6             65.0                  28.8           1.5       37.6               83.8            53.9

Pioneer 2510 wheat was planted using a no-till planter on Oct 22, 1998 following a corn crop on the University of Kentucky Research and Education Center in Caldwell Co. KY. The 4' by 15' plots were arranged in a randomized complete block design with five replications. Fertility was applied as 100 lbs of nitrogen on Feb 26, 1999 (Feekes GS 3-4). The treatments included three different insecticide application dates and an untreated control. Two treatments consisted of single applications of Warrior ® (lambda-cyhalothrin) at 3.2 fl. oz./ac, made with a backpack sprayer in 26 gal of spray per acre, on Nov 24, 1998 (Feekes GS 2-3 ) or Feb 17, 1999 (Feekes GS 3). The third set of plots were treated on both dates. These were compared to an untreated control. Regular aphid counts were not made but plots were checked for aphids just before applications were made. Plots were rated for BYD on May 5, 1999 (Feekes GS 10) by randomly selecting 50 individual plants and examining them for symptoms. Percent of plants displaying BYD symptoms were analyzed for differences using the SAS GLM. procedure.

Significant differences in percentages of plants displaying BYD symptoms, as related to insecticide treatments, were detected (F (3,12 df) = 3.83, Pr>F =0.039) (Table 1). Although very few aphids were seen before the final insecticide application; they were widespread and numerous during the spring.
 

TABLE 1. MEAN PERCENTAGES (± S.E.) OF WHEAT PLANTS SHOWING BYD SYMPTOMS IN PLOTS TREATED WITH WARRIOR INSECTICIDE ON SELECTED DATES TO CONTROL APHID VECTORS OF BARLEY YELLOW DWARF VIRUS.
Time of Application	% of Plants Showing BYD Symptoms ± SE1
No Insecticide	13.2 ± 5.0 a
24 Nov 98	5.6 ± 1.0 ab
24 Nov 98 and  17 Feb 99	1.6 ± 0.4 b
17 Feb 99	3.2 ± 1.2 b

¹Means followed by the same letter are not significantly different. p = 0.5. Ryan-Einot-Gabriel-Welsch Multiple range test.

The November treatment, often made as an 'insecticide only' application, costs about $11.00 per acre. The February insecticide application is often made in conjunction with other inputs, so the application cost may be saved. Therefore, in this location and in this year, the fall, winter, and combination treatments would have cost $11.00, $6.00 and $17.00 respectively.

Assuming the entire difference in percentage of plants showing BYD symptoms was a result of insecticide timing, and that a damaged plant would have about a 20% yield loss, we can compare the relative merits of treating -vs- not treating.
 

No Insecticide Treatment

Using an estimate of 13.2% damaged plants with a 20% yield reduction for each damaged plant, the effective yield loss was calculated to be 2.64%. If this were 100 bu/acre wheat, the resulting loss would be 2.6 bushels. At a price of $2.50/bushel, the untreated acre of wheat would bring about (97.4 bu at $2.50/bu) $243.50 or a loss of $6.60 per acre due to this aphid-vectored disease.
 

Nov 24 & Feb 17 Insecticide Treatment

The best insecticide treatment (two applications) contained an average of 1.65% damaged plants. This indicates that about 88% of the loss to BYD was prevented by the two treatments. As calculated above, this is a 0.3% yield loss per acre. For 100 bu/acre wheat, this loss would be 0.3 bushel, leaving a per acre yield of 99.7 bushels. At $2.50/bu the resulting loss would be $0.75, bringing a per acre return of (99.7 bu at $2.50/bu) $249.25. However, this level of protection was obtained by making two insecticide applications, at a cost of about $17.00 per acre. Reducing the per acre return by this cost leaves a net return of ($249.25 - $17.00) $232.25.
 

Nov 24 Only Insecticide Treatment

The Nov 24 treatment had 5.6% damaged plants. Assuming the standard plant yield loss, this is the equivalent of a 1.1% yield loss per acre. For 100 bu/acre wheat, this loss would be 1.1 bushels, leaving a per acre yield of 98.9 bushels. At $2.50/bu the resulting loss would be $2.75, bringing a per acre return of (98.9 bu at $2.50 /bu) $247.25. However, this level of protection was obtained by making an insecticide applications which would cost about $11.00 per acre. Reducing the per acre return by this cost leaves a net return of ($247.25 - $11.00) $236.25.

Feb 17 Only Insecticide Treatment

The incidence of damaged plants in the Feb 17 treatment was 3.2%. For 100 bu/acre wheat, this loss would be 0.6 bushels, leaving a per acre yield of 99.4 bushels. At $2.50/bu the resulting loss would be $1.50 bringing a per acre return of (99.4 bu at $2.50/bu) $248.50. However, this level of protection was obtained by making an insecticide applications which would cost about $6.00 per acre. Reducing the per acre return by this cost leaves a net return of ($248.50 - $6.00) $242.50.
 

SUMMARY:

Under these test conditions, the insecticide applications did cause statistically significant differences in BYDV symptom expression. However, it is clear that the assumed associated protection of yields resulting from this level of symptom reduction was not cost effective. If all other things are equal, the cost of the insecticide applications was greater than the reduction in damage (Table 2).
 
 

TABLE 2. NET RETURN ($/AC) FROM PLOTS TREATED AT SELECTED TIMES WITH AN INSECTICIDE APPLICATION TO CONTROL APHID VECTORS OF BYDV IN CALDWELL CO., KY. 1999
Treatment	No-Insect.	Nov 24 & Feb 17	Nov 24	Feb 17
Net Ret/ac	$243.50	$232.25	$236.25	$242.50

The circumstances and yield potential on your farm will alter these figures. As prices and yields decline and treatment costs increase, the insecticide treatments will look even less appealing. However, a rise in prices and yields coupled with a lower treatment costs will make the returns from insecticide applications look much more favorable.

Choosing a 100 bushel per acre yield as a basis for comparison may be misleading. 'Intensive Wheat Management' has used 100 bushels as a benchmark; however, many fields will not support this level of production. When yields change so do the level of expenses that can be supported. Using the percent damage estimates, and assumed costs of control from the previous examples we have calculated the necessary value of a bushel of wheat needed to support the three treatments at various yield levels, using the BYD intensity seen in the 1998 experiment (Table 3).
 
 
 

TABLE 3. THE VALUE ($) OF A BUSHEL OF WHEAT REQUIRED TO OFFSET  THE COSTS OF VARIOUS INSECTICIDE TREATMENTS.
Potential Yield (Bu/Ac)	Fall Treatment @ $11/Ac.	Winter Treatment @ $6/Ac.	Fall & Winter Treatments  @ $17/Ac.
100	7.23	3.00	7.35
90	8.03	3.33	8.17
80	9.04	3.75	9.19
70	10.33	4.29	10.49
60	12.06	5.00	12.23
50	14.47	6.00	14.66
40	18.09	7.50	18.47
30	24.12	10.00	24.64

There is no consistently successful strategy to reduce losses to BYD virus by trying to control their aphid vectors with insecticidal sprays. While sprays may kill many aphids and reduce the percentage of infected plants, potential yield savings may not pay for the chemical and application. There are many other factors that impact the relative effect of BYDV infections.

BYDV infections developed very late in the 1998-1999 crop, probably because of very low aphid numbers during the fall. The aphids that were present did not arrive until December. The late aphid flight probably resulted from the late summer-early fall drought that affected Kentucky.

The lateness of the aphid/BYDV infections is illustrated by the fact that the late winter (Feb. 17) application was just as effective at reducing BYDV symptoms as either of the other two applications (Table 1). A larger than "normal" portion of the infections occurred after Feekes GS 3. Because of this, the data presented in Table 3 must be used very carefully. If you consider only Table 3, it appears that the most appropriate time to make an insecticide application is in the late winter. While this was true in 1998-99, this may not be the case in most years. If both aphids and BYDV had been present very early in the fall, the percentage of infected plants and the relative damage to each would have been much greater. While late infections may be important in a year of good prices and low costs, an early fall infection is always a more important consideration.
 

ACKNOWLEDGMENTS:

The authors express their gratitude to Dr.'s Don Hershman (Plant Pathology) and Lloyd Murdock (Agronomy) for their review of this publication. We also especially appreciate the time and work of Dr. Dick Trimble (Ag. Economic) in proofing and challenging our economic arguments.

Patterson variety wheat was planted on Oct 16, 1998 in 4' by 15' plots on the Alexander Farm in Henderson Co. KY. The experiment was arranged in a randomized complete block design with four replications. The test area was most recently in corn and a conventional seed bed was prepared by moldboard plow followed by a discing. Fertility was applied as 35 lbs N on Feb 15, 1999 (Feekes GS 3) and 65 lbs. on March 22, 1999 (Feekes GS: 5). Insecticide applications of Warrior® (lambda-Cyhalothrin) at 3.2 fl.oz. per acre were made with a backpack sprayer in 26 gal of spray per acre, on Nov 24, 1998 (Feekes GS: 2-3 ), Feb 16, 1999 (Feekes GS: 3), both dates or neither date. A fungicide application of Tilt® at 4 fl.oz. per acre was made to all plots on April 29, 1999 (Feekes GS:10.3-5) using a backpack sprayer delivering 25 gal of spray per acre. Plots were observed for BYD symptoms but pressure was too light to warrant rating. Regular aphid counts were not made but plots were observed at application times. Plots were harvested in June 1999 using a small plot combine. Harvested grain was weighed, and check for moisture content. Plot grain weights were corrected to a moisture standard of 13.5% and yields per acre were calculated based on a standard 60 lbs. per bushel. Yields and test weights were analyzed for differences using SAS, Proc GLM..

Plot yields and test weights ± their Standard Errors (SE) are shown in Table. 1. No significant affect was detected on yields (F=1.13) or test weights (F=1.47) for any of the insecticide treatments. This was expected as BYD pressure was very light in these plots and could not account for any differences. Very few aphids were seen before the final insecticide application. However, aphids were wide spread and numerous during the spring.
 

TABLE 1. YIELD AND TEST WEIGHT OF WHEAT HARVESTED FROM PLOTS WITH VARIOUS INSECTICIDE TREATMENTS FOR CONTROL OF APHID VECTORS  OF BARLEY YELLOW DWARF VIRUS.
Time of Application	Yield ± SE	Test Weight ± SE
	(Bu / Acre)	(Lbs. / Bu)
No Insecticide	94.3 ± 6.7	57.8 ± 0.9
Nov 24, 1998	94.7 ± 6.5	55.2 ± 3.3
Nov 24, 1998 and Feb 16, 1999	102.3 ± 2.3	62.9 ± 5.3
Feb 16, 1999	100.8 ± 2.1	55.8 ± 2.5

Such variations as did occur were largely due to lodging in some of the plots. This problem is partially illustrated (Table 2.) by the difference in yields among replications. If all the difference in yields were due to treatments (in this case the insecticide applications), we would expect that yields and test weights calculated for replications (since each replication contains all the same treatments) would be nearly equal. It is obvious that this is not the case, so something other than insecticide treatment is causing the differences in yield and test weight. A portion of this difference is random chance and a portion is likely to be due to the lodging.
 

TABLE 2. YIELD AND TEST WEIGHT BY REPLICATION OF WHEAT HARVESTED FROM PLOTS WITH VARIOUS INSECTICIDE TREATMENTS.
Replication*	Yield ± SE	Test Weight ± SE
	(Bu / Acre)	(Lbs. / Bu)
1	91.4 ± 5.6	57.8 ± 3.1
2	95.5 ± 6.7	57.8 ± 0.8
3	101.3 ± 1.6	55.6 ± 2.4
4	103.9 ± 2.0	63.7 ± 5.1

* Each replication contains all four insecticide treatments.
 

Because the insecticide treatments did not produce any difference in yield at this location and year, using them would have reduced the producers profit. In general terms the fall application is often made as an "insecticide only" application, which would cost about $ 11.00. The spring application is often made in conjunction with other inputs so the application cost may be saved. Using this as the basis, in this location in this year, the insecticide applications would have returned the following: Nov (-$11.00), Feb (-$ 6.00) and Nov and Feb (- $17.00).

Certainly the circumstances on your farm will alter these figures. As prices and yields decline and treatment costs increase, the insecticide treatments will look even less appropriate. However, as prices and yields increase and treatment costs decrease the insecticide applications will look better.

Deciding whether or not to treat for control of aphid vectors of BYDV is a hard decision to make in KY. You do the best you can based on the information available at the time the decision has to be made. However, it is important to remember that spraying "just in case" is very often not profitable and even if you see symptoms in the spring that does not necessarily mean that you made the wrong decision by not spraying in the fall or winter.

The author thanks Mr. Mike Smith for arranging for the location and Mr. Alexander for allowing the use of his farm, Dr. Lloyd Murdock and Ms. Dottie Call for making fertility applications, Dr. Don Hershman for applying the fungicide, Mr. Charles Tutt for harvesting the plots, and Ms. Call for coordinating the various efforts.

OBJECTIVE:

The spread of Italian ryegrass has often been attributed to scattering of weed seed with combines during wheat harvest. Limited observations indicate that Italian ryegrass matures slightly later than wheat. If this observation holds true, the use of Roundup Ultra as a preharvest treatment after wheat seed are physiologically mature but before maturity of Italian ryegrass may help limit viability of Italian Ryegrass seed.

This project was conducted to evaluate Italian ryegrass and wheat seed viability following the use of Roundup Ultra applied and Gramoxone Extra as preharvest treatments at different timings to two wheat varieties of different maturities. Roundup Ultra at 2pt/A is labeled for applications after the hard-dough stage of wheat grain (30% or less moisture) at least 7 days before harvest. Gramoxone Extra is NOT registered as a preharvest treatment in wheat but was included in this study for making comparisons with Roundup Ultra.
 

METHODS:

The wheat varieties chosen for this study were Clark and Pioneer 2540.

According to the 1998 Kentucky Small Grain Variety Trials Progress Report, Clark reaches the heading stage about 5 days earlier than Pioneer 2540. Wheat was planted in a conventional tillage system in an Italian ryegrass infested area on October 13, 1998 at the University of Kentucky Research and Education Center. Wheat stand counts were recorded on October 28, 1998. A total of 110 units of nitrogen/A was applied as a split treatment with 50 units/A applied on February 22, 1999 and 60 units/A on March 26, 1999. The preharvest treatments were applied at various times during the drying of wheat with a CO₂ back-pack sprayer. Roundup Ultra at 2 pt/A was applied in a spray volume of 8 GPA. Gramoxone Extra at 2 pt/A plus nonionic surfactant at 0.25% v/v were applied in a spray volume of 17 GPA.

The intended moisture levels used for timing the preharvest treatments were designated as 40% (physiological maturity), 30% (maximum moisture based on Roundup Ultra label), and 20% (acceptable moisture level for machine harvesting). Wheat seed moisture was measured using the oven dry method. The time required for this method was nearly one day, consequently, the rapid maturing conditions in 1999 made it impossible to apply all of the preharvest treatments according to the target seed moisture levels.
 

RESULTS:

Natural drying process was approximately 3 to 6 days earlier for Clark than for Pioneer 2540. Clark seed moisture measured 56.8 % on June 4, 39% on June 5, and dropped to 20.6% on June 6. By the time moisture levels were determined, the intended target levels of 40% and 30% for Clark had already passed. Similar problems were encountered for Pioneer 2540 at the 30% level.

None on the preharvest treatments affected the germination of wheat seed. The germination results ranged from 85 to 90 % for Clark and from 83 to 86 % for Pioneer 2540.

The germination of Italian ryegrass was 97% for seed collected from the nontreated check plots for both Clark and Pioneer 2540. The preharvest applications of Roundup Ultra at 2 pt/A did not appear to affect the germination of Italian ryegrass, even at the earliest application made to Clark on June 6. The percent germination of Italian ryegrass seed ranged from 91 to 97% for the Roundup Ultra preharvest treatments made during the period between June 6 through June 16, 1999.

All preharvest applications of Gramoxone Extra at 2 pt/A plus nonionic surfactant at 0.25% significantly reduced Italian ryegrass seed germination when compared with the nontreated check. The Italian ryegrass seed germination from the Gramoxone Extra ranged from 12 to 19% for applications made to Clark during the period of June 6 through June 8. The germination results ranged from 25 to 75% for Gramoxone Extra applications made in Pioneer 2540 plots during June 9 through June 16.

One observation worth noting from this study was the impact that Italian ryegrass had on wheat growth. Fall wheat stands were uniform and averaged approximately 31.5 plants/ft² for both Clark and Pioneer 2540. The Italian ryegrass population was extremely dense in portions of the study and severely limited growth of wheat during late winter and spring. A rating of percent ground cover occupied by wheat on July 8 was used to reflect the affect Italian ryegrass had on biomass of wheat. The biomass ratings were highly variable and were not affected by the preharvest treatments. Although both varieties were affected by competition, there was a definite trend indicating that Pioneer had less biomass and may be more prone to competition from Italian ryegrass than Clark.
 

SUMMARY:

Preharvest applications of Roundup Ultra appear to be relatively safe to wheat when applied according to label directions. Although Roundup Ultra may aid in managing selected weeds, it is unlikely that it will reduce the viability of Italian ryegrass seed. Gramoxone Extra can reduce the viability of Italian ryegrass seed, particularly when applied to a short season wheat variety that allows for earlier applications. It is important to note that Gramoxone Extra is currently not registered as a preharvest treatment to wheat.
 

ACKNOWLEDGMENTS:

We wish to express appreciation to the Kentucky Small Grains Growers Association for partial support in funding this research and to the Division of Regulatory Services at University of Kentucky for conducting the seed germination tests.
 
 

TABLE 1. VIABILITY OF SEED COLLECTED FROM WHEAT AND ITALIAN RYEGRASS AND WHEAT BIOMASS FOLLOWING PREHARVEST APPLICATIONS OF ROUNDUP ULTRA AND GRAMOXONE EXTRA IN CLARK AND PIONEER 2540 (PRINCETON, KY 1999)
Variety		Wheat Moisture		Preharvest Herbicide Treatment1	Seed Germination 2		Wheat  Biomass 3 %
	Date	Intended %	Actual %		Wheat    Germ %	Italian     Ryegrass  %
Clark	6/6	40	20.6	Roundup Ultra	85	97	29
				Gramoxone Extra	88	13	24
	6/7	30	20.4	Roundup Ultra	90	91	46
				Gramoxone Extra	86	12	33
	6/8	20	10.13	Roundup Ultra	85	95	29
				Gramoxone Extra	88	19	49
	Nontreated Check				88	97	34
Pioneer 2540	6/9	40	37.2	Roundup Ultra	88	96	19
				Gramoxone Extra	83	25	4
	6/10	30	22	Roundup Ultra	86	95	9
				Gramoxone Extra	86	45	13
	6/16	20	10	Roundup Ultra	84	97	23
				Gramoxone Extra	86	75	9
	Nontreated Check				86	97	13
					NS	11	31
1 Roundup Ultra at 2 pt/A was applied in a spray volume of 8 GPA. Gramoxone Extra at 2pt/A plus nonionic surfactant at 0.25% were applied as tank mixture in a spray volume of 17 GPA. 2 Wheat and Italian ryegrass seed were hand collected on 6-29-99 for germination tests conducted by UK Regulatory Services. 3 Biomass ratings were made on 7-8-99 and represent visual ratings of percent ground cover occupied by wheat.

 

INTRODUCTION:

Numerous weed species can infest wheat in Kentucky and several of these are particularly troublesome and can decrease wheat yield. Cheat, hairy chess, and Italian ryegrass are especially troublesome and difficult to control with currently available herbicides. Chickweed, purple deadnettle, henbit, and several mustard species are also problems. Because of the occurrence of these weeds, wheat growers are interested in the evaluation of herbicides labeled for use in wheat. There are several herbicides labeled for wheat in states other than Kentucky, primarily in continuous wheat. Double-cropped soybeans follow essentially all of the wheat grown in Kentucky and herbicides used for wheat weed control must not persist in soil and cause injury to soybeans.
 

OBJECTIVE:

Determine if wheat herbicides applied in the fall or spring cause injury to double-cropped soybeans.
 

METHODS:

Wheat was planted in October of 1997 and 1998 at Princeton and 1998 at Lexington. After wheat harvest in June of 1998 and 1999, soybeans were planted no-till into the standing wheat stubble. Two soybean varieties were evaluated: AG 4501, an STS (sulfonylurea tolerant soybean) and AG 4702, a non-STS. Several of the wheat herbicides discussed in this report kill weeds (and crops) by inhibiting the acetolactate synthase enzyme (ALS). STS soybeans were developed because of their tolerance to ALS inhibiting herbicides and we were interested in knowing if STS soybeans would be tolerant to these wheat herbicides.

Wheat herbicides were evaluated for double-crop soybean injury at Princeton in 1998 and 1999 and Lexington in 1999. Treatments were applied to actively growing wheat in late November and in mid-March. Soybean injury was evaluated in mid-August, 8 weeks after soybean planting. Listed in the following table are products evaluated in these studies:
 

HERBICIDE	RATE	ACTIVE INGREDIENTS
Harmony Extra75 DF	0.6 oz/A	*thfensulfuron & *tribenuron
Peak 57 WDG	0.75 oz/A	*prosulfuron
Ally 60 DF	0.1 oz/A	*metsulfuron
Maverick 75 WSG	0.5 oz/A	*sulfosulfuron
Assert 2.5 E	1.5 pt/A	*imazamethabenz
Sencor 75 DF	3 oz/A	metribuzin
Curtail 2.38 E	2.5 pt/A	clopyralid + 2,4-D

* ALS-inhibiting herbicides

 

RESULTS:

No injury was noted in 1998 to either soybean variety from fall or spring applications of the herbicides (Table 1). Rainfall was below normal from the time of wheat planting, and fall herbicide applications, until the spring herbicide applications in 1998. However, 22 inches of rainfall was received on the plots in April, May, and June. This excessive rainfall probably contributed to a more rapid herbicide loss in the spring. Substantial soybean injury was noted in 1999 at Princeton and Lexington (Table 1). Rainfall from the time of wheat planting until the spring herbicide treatments was near normal at Princeton and slightly below normal at Lexington.

Peak and Maverick caused the greatest injury in Princeton with fall and spring treatments on the non-STS variety with the spring treatment having greater injury. However, the STS variety exhibited much less injury from Peak and Maverick. Ally applied in the fall caused 10% injury to the non-STS and 3% injury to the STS variety at Princeton. A similar response was noted with the fall treatment of Maverick to the STS variety. Assert , Harmony Extra and Sencor caused little, if any, injury at Princeton. The spring treatment of Peak produced the greatest injury to the non-STS variety at Lexington. Maverick injury was less at Lexington compared to Princeton for the non-STS variety. Less injury was noted at both locations with the STS variety for Harmony Extra, Peak, Ally, Maverick, and Assert.

Although Curtail is not an ALS-inhibiting herbicide it did cause injury to double-cropped soybeans at Princeton with the spring treatment and the fall and spring treatment at Lexington. The clopyralid component of Curtail is believed to have persisted in soil and caused injury to the double-cropped soybeans.

Over all locations, soybean yield was low (Table 2). Rainfall at Princeton in 1998 was very limiting during the soybean-growing season, although soil moisture was excellent at the time of planting. Soybean yield in 1999 at Princeton was low and averaged about 12 bushels per acre and was attributed to the low rainfall received during the soybean-growing season. The plots at Lexington were not harvested. These soybeans never produced pods with seeds due to the severe lack of water at this location. It was difficult to draw conclusions from these yield data because of the relatively low, to very low, yields; however, the greatest soybean injury was noted in 1999 with a spring treatment of Maverick and this treatment produced the lowest yield (Table 2). Curtail injury also reduced yield in 1999. Yield was generally greater with the STS variety compared to the non-STS variety in 1999.

SUMMARY:

This research shows the importance of following label restrictions regarding rotational crops. Some of the wheat herbicides in these studies persisted in the soil and caused injury to double-cropped soybeans during a year when the amount of rainfall was below normal. The magnitude and risk of soybean injury from most ALS-inhibiting herbicides in this study tended to be greater for spring applications compared with fall applications. The STS variety used in these studies exhibited less soybean injury than the non-STS variety. This response is encouraging because it might allow for the use of some herbicides for wheat weed control that could not be used. However, additional research under more "normal" climatic conditions is needed.
 

TABLE 1. SOYBEAN INJURY OF NON-STS AND STS VARIETIES AT PRINCETON IN 1998 AND 1999 AND LEXINGTON IN 1999. SOYBEAN INJURY WAS EVALUATED IN MID-AUGUST OF EACH YEAR.
		PERCENT SOYBEAN INJURY
		Princeton 98		Princeton 99		Lexington 99
Herbicide	Timing	Non-STS	STS	Non-STS	STS	Non-STS	STS
Harmony Extra	Fall	0	0	3	0	0	0
Harmony Extra	Spring	0	0	0	0	0	0
Peak	Fall	0	0	10	0	7	0
Peak	Spring	0	0	23	3	40	0
Ally	Fall	0	0	10	3	0	0
Ally	Spring	0	0	3	0	3	0
Maverick	Fall	0	0	13	7	0	0
Maverick	Spring	0	0	47	0	13	0
Assert	Fall	0	0	0	0	10	0
Assert	Spring	0	0	3	3	7	7
Sencor	Fall	0	0	0	0	0	0
Sencor	Spring	0	0	0	0	13	0
Curtail	Fall	0	0	0	0	10	0
Curtail	Spring	0	0	23	10	13	3
LSD (0.05)          NS                NS                22                  8                  15                    6

 

TABLE 2. SOYBEAN YIELD OF NON-STS AND STS  VARIETIES AT PRINCETON IN 1998 AND 1999
		SOYBEAN YIELD (BU/AC)
		Princeton 98		Princeton 99
Herbicide	Timing	Non-STS	STS	Non-STS	STS
Harmony Extra	Fall	15	19	12	13
Harmony Extra	Spring	18	17	13	13
Peak	Fall	18	18	12	18
Peak	Spring	13	26	13	16
Ally	Fall	16	18	12	13
Ally	Spring	26	21	10	12
Maverick	Fall	28	22	14	14
Maverick	Spring	17	23	7	12
Assert	Fall	18	15	14	12
Assert	Spring	17	15	11	13
Sencor	Fall	25	19	15	15
Sencor	Spring	25	23	13	15
Curtail	Fall	24	24	13	14
Curtail	Spring	26	22	9	14
LSD (0.05)                    NS                     NS                     NS                         NS

This study was initiated to see if there is any particular nutrient that is deficient in wheat in Kentucky.

Since soil tests are not highly reliable for secondary and micro nutrients, plant concentration of these nutrients in the plant are a more reliable indicator of any of these nutrient problems. Sampling as late as possible (just prior to flowering) improves the chances of a better test.

Areas in each field approximately 150 ft by 450 ft were chosen for intensive soil and plant sampling. Soil samples were taken from the areas at least 60 days after fertilization. Sampling depth was 0 to 6 inches for fields that had been tilled and 0 to 4 inches for fields that were no-till planted to wheat. Samples were also taken at the 12 to 18 inch depth on half of fields to look at nutrient concentrations in the lower part of the soil profile.

The plants were sampled at initial heading just prior to flowering. The flag leaf was taken on 100 to 150 plants in the sample area. The leaves were dried and ground soon after collection.
 

RESULTS AND DISCUSSION:

The plant nutrient concentrations are found in Table 2 and the soil test results are in Table 3.

Below is the sufficiency range for the plant nutrient concentration for wheat flag leaf at
head emergence.
 
 
 

TABLE 1. GENERAL TOTAL NUTRIENT SUFFICIENCY RANGES FOR SELECTED CROPS IN THE SOUTH AT OR NEAR REPRODUCTIVE GROWTH (TAKEN FROM NUMEROUS PUBLISHED SOURCES).
Nutrient	N	P	K	S	Ca	Mg	Fe	Mn	Zn	Cu	B
Concentration	%	%	%	%	%	%	ppm	ppm	ppm	ppm	ppm
Wheat (flag leaf)	3.0 to 4.5	0.25 to 0.5	1.5 to 3.0	0.20 to 0.5	0.30 to 1.0	0.16 to 1.0	25 to 300	20 to 475	16 to 70	6 to 25	6 to 20

This is the sufficiency range which means there is absolutely no problem with the amount of nutrients in the plant. One can be a little below these concentrations and not have a problem.

There is a critical range at which one might become concerned that the nutrient might actually be reducing yields.

The concentrations in Table 2 show absolutely no problem on any field for N, P, K, Ca, S, Fe, Mn. All of the samples are in or very near to the sufficiency range. Sulfur, which is sometimes suspected of being deficient by some agronomists, is very high. This indicates that all these fields have a good supply of sulfur. Although a sulfur soil test is not a very reliable test, when more than 20 lb/ac of S is in the soil it is considered sufficient. All of the fields had more than this in the surface soil sample.

The remaining nutrients are Zn, Cu and B.

Only one sample had less than 16 ppm of Zn (Mashburn in Caldwell Co.). The 12 ppm is not critically low but indicates that it is on the low side but is probably not reducing yields. The soil test results from this site show a high pH and a very high P content. Both of these will reduce Zn availability. The Zn soil test on this site was high and should be sufficient to supply adequate Zn to small grains and corn (which is the most sensitive crop).

About half of the sites had a Cu content below the 6 ppm. However, none were in the critically low 3 ppm so these probably do not present a problem on these soil types.

Boron (B) is the most interesting nutrient studied. Only 2 sites were above 6.0 ppm. According to Dr. Jim Woodruff of U.S. Borax, the critical concentration is probably below 3 ppm. There are some sites in this range. Even though there are some sites in this range, Dr. Woodruff points out that it is very difficult to get a response to wheat from boron and very few yield increases have been reported. It is difficult to get a yield response from B applied to the soil. Some states recommend 0.25 lb/a of B at about heading and it can be applied with a fungicide. If this is done it should be applied as test strip because response is not assured.

We will probably continue the nutrient survey one more year in some other counties to see if the 2000 results support the 1999 results. We may do some B trials if the farmers would like to cooperate on the project.
 
 

TABLE 2. 1999 NUTRIENT SURVEY OF WHEAT.
	Plant Nutrient Concentration
County	N	P	K	Ca	Mg	S	B	Cu	Fe	Mn	Zn
	-----------------------%----------------------						---------------ppm---------------
Caldwell County Cotton Mashburn     Calloway County Kelly Furches     Fulton County Burnette (Casey) Burnette (Jersey)       Hancock County Boswell Myer       Hardin County Rogers Wooden       Simpson County Carter Snyder	4.2  3.6       3.7 3.7         4.6 5.1         4.1 4.2       3.5 3.6         3.3 4.2	0.30  0.40       0.33 0.39         0.41 0.34         0.38 0.37       0.30 0.39         0.37 0.40	1.8  1.5       1.4 1.5         1.6 1.5         1.7 1.6       1.7 1.7         1.5 1.5	0.65  0.6       0.53 0.64         0.85 0.71         0.62 0.50       0.66 0.43         0.69 0.71	0.16  0.21       0.20 0.14         0.25 0.31         0.21 0.17       0.16 0.12         0.21 0.20	0.44  0.34       0.33 0.37         0.44 0.56         0.46 0.44       0.40 0.29         0.36 0.43	3.2  3.7       3.2 3.0         2.8 3.5         3.9 3.0       3.0 2.3         6.6 7.6	5.1  6.2       4.5 3.8         5.9 7.3         7.5 6.4       4.3 6.3         6.2 5.1	93  69       94 85         104 95         101 82       90 92         74 87	128  56       65 74         44 120         129 59       111 67         105 124	19  12       16 17         21 22         22 20       17 19         26 23

 
 
 

TABLE 3. 1999 NUTRIENT SURVEY OF WHEAT
County	Sample depth (inches)	Extractable Soil Nutrients (lb/ac)
		pH	P	K	Ca	Mg	S	Zn
Caldwell County Cotton   Mashburn   Calloway County Kelly Furches       Fulton County Burnette (Casey) Burnette (Jersey)       Hancock County Boswell Myer       Hardin County Rogers   Wooden   Simpson County Carter Synder	0-6  12-18 0-6       0-6 0-6 12-18         0-6 0-4 12-18       0-6 0-6 12-18         0-4 12-18 0-6       0-6 0-6 12-18	6.6 6.1 6.9       6.5 6.8 6.3         6.7 6.2 4.8       7.0 6.7 4.6         7.0 6.3 6.9       6.5 5.7 5.5	100  2 201       69 197 16         166 95 36       99 135 11         100 3 148       124 184 6	408  258 260       229 359 227         309 279 245       257 311 137         264 178 357       286 369 247	3740  2600 3310       3210 3430 2350         3530 3290 1750       3200 3740 1000         2840 2450 3530       1570 1720 2070	209  332 151       129 126 74         206 356 498       139 203 103         188 84 187       133 150 191	32  54 26       66 44 18         52 68 42       38 48 86         26 46 24       28 30 40	1.3  0.2 4.9       0.8 2.5 0.0         5.0 3.8 0.6       1.4 2.3 0.5         2.3 0.2 1.5       12.0 8.5 0.0