Stored Grain Pests & Monitoring Options
Wheat Spindle Streak Mosaic Variety Ratings for 1997
Amisorb on Wheat
Nitrogen Rates & Time of Application on Wheat
Fall vs. Spring Herbicide Treatments
18 Steps for Maximum Winter Wheat Yields
Ky Small Grain Variety Trials
Harvested wheat that is held in on-farm storage for several months is prone to serious damage by stored grain insects, especially weevils and flour beetles or "bran bugs". Stored product insects can damage kernels or feed on fines. Also, water produced by their metabolic processes can lead to "hot spots" in the grain mass. In addition, the mere presence of insects in wheat can result in dockage or rejection.
Infestations of insects in stored wheat begin in or around the bin or nearby storage areas for animal feeds. An aggressive sanitation program coupled with a preventive bin spray will greatly reduce the potential for problems but all sources around the farm cannot be eliminated. Wandering adults can enter the grain mass and start an infestation at any time.
There are two main ways to monitor for stored grain insects that will allow you to detect problems early and take effective action.
Active sampling involves entering the bin at regular intervals and using tools such as a partitioned grain trier or deep cup (bin probe). These are inserted into the grain and opened to obtain samples from different depths in the mass. The grain can be tested for moisture and examined for insects or damage. A temperature probe can be used to take readings when the grain samples are collected.
Passive sampling uses pheromone traps or unbaited traps to capture insects that are moving in the grain mass. Storgard® products provide a variety of options in trap design and pheromone lures. The WB II reusable grain probe kit functions like a minnow trap in that the plastic tube has holes that allow insect entry but escape is very difficult. The durable, reusable tubes are left in place and can be retrieved regularly to look for insects that have been captured as they move through the mass.
Treatment options for binned grain are limited. Fumigation with aluminum phosphide (Phostoxin, etc.) is effective in controlling insects throughout the bin in an established infestation, but requires training and unique tools to disperse the pellets or tablets in the grain mass. Also, the bins must be sealed completely to hold the gas at the proper level for the appropriate amount of time. There is no residual effect so re-infestation may occur.
Grain protectants can be used for control if fumigation is not an option. This requires moving the grain so that the insecticide can be distributed evenly through the grain mass. Infested grain can be treated as it is moved to another bin or temporarily into wagons or trucks. This approach is necessary if the insects are distributed throughout the grain mass. Malathion (Cythion) or Reldan can be applied to wheat as a spray while the grain is passing by on an auger. Flow rate of the grain must be known so that the application can be calibrated. Some malathion (Cythion) labels contain instructions for application as a grain protectant, others only address treatment of empty bins and equipment. Read the label before buying and using any pesticide.
Although malathion has a powerful smell, it is not a fumigant. Malathion works as a contact insecticide or as a stomach poison. Attempts to blow malathion fumes through the grain will not provide control.
Wheat spindle streak mosaic (WSSM) is an annual problem in many Kentucky wheat fields. However, only rarely does this soil-borne virus disease become as widespread, severe, and long-lasting in susceptible varieties as it did this spring. Normally some fields will show the characteristic yellow dashes of WSSM, but symptoms will disappear as temperatures warm in late April. In contrast, symptoms this spring often remained visible throughout the season, and contributed to premature crop maturity and apparent reduced yields. Increased problems with WSSM this spring are thought to be due to the abnormally cool weather we experienced in April and the first half of May.
Wheat producers do not like to see diseases in their fields and this is understandable. However, big disease years give us the opportunity to assess varietal differences which can help farmers avoid disease problems in future years. The last year we were able to make "good" WSSM ratings was in 1993.
The following table indicates our most current WSSM ratings as indicated according to level of resistance or susceptibility. If you had a problem with WSSM this spring, it would be prudent to select a variety for planting this fall which is rated at least moderately resistant. You never know when we'll have another serious WSSM year, so it is best to only plant varieties with some resistance in fields which have a history of the disease.
Caldwell S Cardinal MS
Clark R Clemens MS
EK 102 S EK 114 S
EK 309 S Elkhart S
Ernie MS Featherstone 520 S
FFR 523 S FFR 525 VS
FFR 555 MS FFR 558 S
Foster MS Glory R
Hopewell MR Jackson S
KAS Justice MS KAS Patriot MS
Madison R NK Coker 9543 MS
NK Coker 9663 S NK Coker 9704 S
NK Coker 9803 MS P2510 R
P2540 R P2548 VS
P2568 R P2552 R
P2684 MS P2737 MR
Patterson MR Pocahantas S
Terra SR 204 MS Terra SR 205 MS
Terra SR 211 MS Verne MR
Voris 6044 MS Wakefield S
Amisorb is a new product being sold commercially that is reported to increase nutrient plant uptake and availability and stimulate root growth. The material was tested by the University of Illinois in the laboratory and showed great promise. However, its success in the field has not been as consistent. This test was designed to measure its effectiveness on winter wheat. The Amisorb was applied in the fall at 1 qt/ac and at the same rate in late winter (Feb. 14) with nitrogen fertilizer. Nitrogen was applied at the rate of 30 lb/ac in February and 60 lb/ac in March. Pioneer 2540 wheat was planted at 35 seeds/ft2 on Oct. 16.
The results are seen in the table below. There was no yield differences
between the two treatments and there were no visual differences between
the treatments throughout the growing season. Chlorophyll readings were
taken at jointing and there were no differences, indicating that nitrogen
was equally available in both treatments. This was in spite of the heavy
rains that fell during early March. At this point, Amisorb does not show
promise as an effective additive to a fertilizer program for wheat.
Yield (bu/ac @ 13.5% H2O)
Amisorb (2 qt./ac) 101
Nitrogen (N) on wheat is an important component of the wheat management package. The rates that should be used and when they should be applied is always on a producer's mind. The rates will change some with the conditions and the management, but there are some guidelines that will always be pretty close.
The following data was gained from a trial on a well-drained soil in southern Christian County. Two varieties of wheat (Foster and Coker 9803) were used and the yields were averaged. Nitrogen (30 lbs/ac) was added to all plots in the fall. The different N treatments were added on Feb. 14 (Greenup) and March 12 (Feekes 5). Wheat was planted on Oct. 16 at the rate of 35 seeds/ac. and protected from insects and diseases with insecticides and fungicides. Corn residue was tilled prior to planting. The planted area allowed for only 2 replications of this experiment.
The results clearly indicate that large amounts of N were lost from the Feb. N application, but the Feb. application was still very important for the overall yield. The yields can be seen in the following table. When 90 lb/ac of N were added in one application in Feb., the yields were only 9 bu/ac. above the treatment with no spring N. This shows the importance of the March application on a wet year. The heavy rains in early March resulted in more than half of the Feb. N being lost before the crop had adequate growth to take up larger amounts of N.
All of the best yielding treatments had N applied in Feb. Indicating the importance of this application. It appeared that 30 and 45 lb/ac of N applied in Feb. were equally effective under these conditions. Treatments 3 and 4 had a total of 90 lb/ac of N applied in Feb. And March with different splits, but the yields were almost identical. The heavy rains in March probably reduced the amount of natural N available to the wheat and caused a reduction in tillers produced during the "green up" stage of growth if some N was not added in February.
The two treatments with the highest yields received a total of 105 and
120 lbs/ac of N in Feb. and March. A total of 90 lb/ac received during
this time was not sufficient for maximum yields this year, indicative of
the high amounts of N lost this spring with the heavy rains.
Tmt N Rate
Yield (13.5% H20)
Feb. Mar. Head/Ft2 bu/ac
2. 45 60 75 88 a
3. 30 60 67 81 ab
4. 45 45 66 79 ab
5. 0 60 66 77 b
6. 0 90 63 75 b
7. 90 0 51 56 c
8. 0 0 42 42 c
Many of the broadleaf weeds in wheat can be controlled when herbicides are applied in a timely manner. Broadleaf weeds that emerge in the fall and overwinter often tend to be difficult to control, consequently, there is an increasing trend to wheat growers to apply herbicide treatments in the fall to weed control.
One of the trials conducted in Christian County compared Harmony Extra (thifensulfuron + tribenuron) applied at 0.5 oz/A in the fall and spring on the effects of weed control and wheat yield. Peak (prosulfuron) was applied at a rate of 0.5 oz/A only in the fall. The current Peak label prohibits rotating to soybeans until 10 months after treatment, therefore Peak is not used in wheat fields that are rotated to double-crop soybeans.
The major weed species in the area was henbit. The non-treated check plots had about 30% ground cover of henbit on April 8, 1997. The fall treatment of Harmony Extra averaged 91% control of henbit compared with an average of 67% when applied in the spring. The poor control observed with Peak supports results of previous studies with this herbicide. Studies in 1996 indicated that Peak applied in the fall controls many problem weeds in wheat including wild garlic, but does not provide acceptable control of henbit.
Although the differences in weed control did not appear to significantly limit wheat yield, there was a slight trend for greater yield when a herbicide was used compared to the non-treated check. The major differences in wheat yield were attributed to variety with Coker 9803 having approximately 20 bushels less per acre compared with Foster and Pioneer 2540.
Conclusion: Fall treatments of Harmony Extra may provide better
control of such cool-season broadleaf weeds as henbit compared with spring
treatments. The differences in control between fall and spring treatments
may not always impact wheat yields. However, experience has shown that
in certain cases, such as no-till plantings, broadleaf weeds can gain a
competitive advantage if not treated with a pre-plant "burndown" treatment
or with a fall treatment following wheat emergence.
1. Test soil to determine fertility of field.
2. Apply P, K, and lime according to soil test.
3. Select several high-yielding, disease-resistant, winter-hardy varieties.
4. Calibrate the drill.
5. For conventional tillage, prepare a good seedbed.
6. For no-tillage, use a contact herbicide.
7. Nitrogen: 30 lb/A in fall as residual or applied.
8. Plant from Oct. 10 to Oct. 30.
9. Plant in 4- to 8-inch row spacings. Tramlines may be established at this time for subsequent applications.
10. Seed 35 (up to 40 for no-till) seeds per square foot of high-quality seed.
11. Apply insecticide as needed for insect control (fall and spring).
12. Check stand density near mid February when winter survival can be rated.
A) If stand is adequate (25 or more plants per square foot), apply 30 to 40 pounds of nitrogen mid to late February.
B) If stand is thin (less than 25 plants per square foot), apply 40 to 50 pounds of nitrogen mid to late February.
13. Apply an additional 50 to 60 pounds of nitrogen at Feekes 5 (mid March).
14. Use proper weed control measures (fall and spring).
15. Apply fungicides as needed for disease control during the growing season.
16. Harvest on time at optimum grain moisture (13% to 15%).
17. Provide and prepare adequate, safe storage space.
18. Market wisely for optimum profits.
In 1997, Kentucky farmers harvested 26 million bushels of soft red winter wheat produced on 500,000 acres. The average yield of 52 bu/a was 1 bushel less than the 1996 yield. Barley yields were 70 bu/a, 4 bushels less than the 1996 yields.
Small grain performance tests were conducted in six of the seven agroclimatic regions of Kentucky. [Summaries are shown on the following pages, as well as the Hopkinsville location which was viewed at the Southern Tier Field Day (May 1997) in Christian Co.] Agricultural areas within each region are considered to have similar soil types and climatic conditions. Each region having a substantial acreage of a small grain commodity will have a trial conducted in that region for that commodity.
The objective of the Kentucky small grain variety trials is to evaluate varieties of barley and wheat that are commercially available or may soon be available to Kentucky farmers. New varieties are continually being developed by agricultural experiment stations and commercial firms. Annual evaluation of small grain varieties and selections provides seedsmen, farmers, and other agricultural workers with current information to help them select the varieties best adapted to their locality and individual requirements.
Since weather, soil and other environmental factors will alter varietal
performance from one location to another, tests are grown in six locations
in the state.
|Variety||Yield (bu/a)||Test Wt. (lb/bu)||Lodging (%)||Height
|Survival (%)||Heading (Apr. 1=1)|
|NK COKER 9663||67.2||57.0||3||42||98||37|
|TERRA SR 205||57.9||55.6||0||37||97||38|
|TERRA SR 211||55.4||54.5||0||36||90||38|
|NK COKER 9803||54.5||58.5||1||33||99||36|
|NK COKER 9704||54.4||58.0||0||33||99||35|
|NK COKER 9543||49.8||55.0||6||33||100||36|
|Average Yield (bu/a)||58.5|
|KENTUCKY 1997 WHEAT VARIETY TRIAL HOPKINSVILLE|
|Variety||Yield (bu/a)||Test Wt. (lb/bu)||Lodging (%)||Height
|Survival (%)||Heading (Apr. 1=1)|
|NK COKER 9663||83.6||57.0||0||43||100||32|
|TERRA SR 211||83.1||57.2||0||39||100||33|
|TERRA SR 205||79.1||56.5||0||41||100||34|
|NK COKER 9803||71.3||58.2||0||36||100||31|
|NK COKER 9704||67.2||57.5||0||36||100||31|
|NK COKER 9543||66.3||53.8||0||35||100||31|
|Average Yield (bu/a)||74.3|