Stripe rust has shown up in wheat crops in Louisiana and Texas. Reports are beginning to come in that Arkansas' crop is also being affected.
“We're seeing a good bit of it here, so Arkansas farmers should be on the lookout,” says Steve Harrison, LSU AgCenter wheat breeder. “Stripe rust is still very active down here and will remain that way as long as night temperatures are in the 50s.”
Harrison isn't sure how much of Louisiana wheat has been sprayed — but says fungicides have been applied to a substantial portion.
“I'm guessing we have 160,000 to 170,000 acres of wheat in the state. We would have had at least twice as much if it hadn't been so wet last fall,” says Harrison.
Gene Milus, Arkansas Extension plant pathologist, says he recently found stripe rust in a field near Kibler, Ark. (outside Fort Smith). There have been other reports of rust found in southwest Arkansas near Lewisville.
“These discoveries are a little later in the season than in years when stripe rust has been a major problem,” says Milus. “By this time in 2000 and 2002, when we had pretty bad cases of the disease, there was a lot more found. Hopefully that means we'll only have a mild case this year.”
Arkansas' wheat is actually looking good says Jeremy Ross, Arkansas Extension wheat and corn verification coordinator.
“I've been really surprised and well pleased at how wheat has turned around in the last month. We've been getting reports out of both Louisiana and Texas about stripe rust. With the winds blowing so hard out of those states, it isn't all that shocking to hear that rust has been found in Arkansas fields,” says Ross.
Harrison says Louisiana farmers are also seeing crown rust and stem rust on oats and leaf rust is beginning to develop.
“At this point, stripe rust is by far the most severe,” says Harrison. “But while stripe rust will have played out in a couple of weeks, leaf rust is still cooking.”
Milus says everyone should keep a sharp eye on wheat crops.
“What I suspect is both stripe rust and leaf rust will continue to blow in,” says Milus. “The strength of the wind lately tells me spores are coming. Leaf rust could still become a problem, but it's probably a bit too late for stripe rust to hurt us badly. That could change if the weather cools off.
“Here's something worth mentioning: I'm seeing aphids everywhere I look. Barley yellow dwarf — a viral disease vectored by aphids — is showing up. Having so many aphids out probably means reports of barley yellow dwarf sightings will increase.
“On the positive side, soilborne viruses would have shown up by now if they were going to be bad. So it looks like a really mild year for those.”
The Louisiana wheat crop is mostly at average heading, says Harrison. “But there is a big variation in maturity levels because planting dates were so broad in Louisiana: Baton Rouge wheat is at average heading, Crowley wheat is beyond average heading and Winnsboro wheat is just starting to head.”
“At one point, USDA was projecting Louisiana at 250,000 acres of wheat,” says Ed Twidwell, Louisiana Extension wheat specialist. “Not all of that was planted because we were so wet last fall. I'm guessing something like 150,000 acres ended up planted in wheat. What percentage of that goes through to harvest is hard to gauge — we've had some acres abandoned.”
Wheat fields should be scouted during April for signs of rust diseases, says Rick Cartwright, Arkansas Extension plant pathologist. “Fields with yield potential of 50 bushels per acre and better with active stripe rust in early April would likely benefit from a fungicide application. Cool, moist weather favors stripe rust.”
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