Over the last two weeks of August, a lot of diseases have crept into Arkansas' full-season soybeans.
“We're getting lots of call on stem canker and sudden death syndrome (SDS),” says Chris Tingle, state Extension soybean specialist. “Both of those are kind of erratic and we normally don't have big problems with them. Breeders and producers have been very good about picking resistant varieties. But this year, for whatever reason, some growers went with varieties that aren't resistant. As a result, we're seeing big problems.
“I walked a number of fields in Clay County yesterday. SDS was a big problem in some of those fields. Diseases are a hot topic right now. Everyone wants to know the best options.”
Aerial blight has tapered off following “a large number” of acres being treated with fungicides.
“Frogeye leafspot is another one we've had to deal with.”
Current weather patterns are really hurting the crop, says Tingle. Several weeks ago, when the state was getting rains, humidity levels were very high. Fields had fog, heavy dew and rains on top of that.
“When you have hot, humid conditions inside the plant canopy, pretty much all day, that's an optimum environment for disease like frogeye leafspot.”
The early-season stresses — whether dry spells as was seen in Clay County or too much water as in Poinsett County — set the state's soybeans up for diseases like charcoal rot. Those diseases get into the plant early, but don't really express themselves until reproductive stages are reached.
“So now we're seeing many dead plants from charcoal rot and other diseases.”
Insect-wise, in south Arkansas late soybeans are being treated for soybeans loopers. Looper populations are “really blowing up down there.
“We're also still seeing quite a few stink bugs. The numbers haven't exploded, but a lot of fields are being treated for populations that creep up to the threshold. Corn ear worms/cotton bollworms that we've been battling all year are still bothering us. We're also picking up some bean leaf beetles.”
Tingles suspects Arkansas producers have treated more acres with fungicide this season than last. That's a major expense — “something like $18 to $20 per acre. We can back off insecticide rates a little and save some money, but there are still a lot of fields being treated.
“I think our growers have a lot invested in this crop. We need a bumper yield to off-set those costs. Bumper yields are still possible. I'm reluctantly saying we've still got a decent crop. We just need a break with temperatures — especially the high night temperatures. It just doesn't cool down and plants that are in the seed-fill stage are suffering. The early beans that are coming off are yielding well. I hope they're setting a mark our later beans will meet.”
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