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Kentucky News updated as of
September 9 , 2007
- Hello Everyone,
Below is the current map of soybean rust (SBR) distribution in the US. There was a find in northeast Arkansas this weekend that is getting pretty close to KY.
SBR models indicate that the chances are high that spores of the SBR fungus were deposited into west Kentucky sometime this weekend and infection probably took place. However, recall that it has been extremely hot and dry all across west Kentucky beginning the end of July through this most recent rain system. Yes, there have been times of pop-up thunder storms here and there, but those types of rain events are relatively unfavorable for SBR spore transport, deposition, and infection compared to the consistent wet weather, moderate temperatures, and constant cloud cover that has existed over most of west Kentucky beginning last Friday and extending into today.
In my mind the risk that soybean rust infections have now taken place across west Kentucky is fairly high. This said, the spore load would have been dilute enough that the resulting levels of infection that will be associated with this weekends event’s will be very low. Plus, we will not see evidence of infection until Sept 17 at the earliest (note: we may find it this week in parts of north central and northeast KY that received rain a while back when the remnants of Erin came through, but this has been discussed in previous updates).
With an awareness that infections had almost no chance to occur in west Kentucky until now, and knowing that it will be mid- September (at the earliest) until we find any evidence of infections in west Kentucky, and being confident that the initial levels of soybean rust we will find will be low, and knowing that it will take an additional 2 weeks or more for the disease to increase following an initial find; I am very confident in saying that we will not need to spray soybean in Kentucky for soybean rust this season. The only exception may be if you have a field that will require time in October to make yield. My guess is that there will be very few, if any, fields in this situation by the beginning of October. I have a pretty lame field of July 2- planted beans I am watching (MG 4.5) here at Princeton, and they are at stage 5.5 (seed in pods nearing full size). By the time we would find soybean rust in west Kentucky (Mid- Sept at the earliest) and by the time the disease begins to increase (early October at the earliest), my field (as well as almost all (if not all) fields in the state) will be into the R6 stage. This is the stage when spraying would have no additional yield benefit even if some SBR developed.
The bottom line is this: even though we have probably had very low levels of SBR infection in west Kentucky, according to the above thought process, I continue to suggest that spraying for soybean rust not needed. If anything changes this recommendation, I will be the first to let you know. But at present, this is how I see the situation. Note: Arkansas, in general, and the area of the new find, specifically, has had much more rain than we have had. Thus, they have had more opportunities for soybean rust infections to occur prior to this weekend’s rains. That is how they could “have it” and us not. My guess is they will find SBR in states to our north before we find it. But so far, no soybean rust has been detected in Kentucky or in any states north of Kentucky.
Trainings
- no soybean rust specific trainings
are presently being offered in Kentucky
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