In late March stripe rust is common in Louisiana wheat and Arkansas growers are being advised to closely watch wheat fields for the disease.
“In general, the wheat crop in the southern half of Louisiana — along the Gulf Coast — isn’t very good,” says Steve Harrison, LSU AgCenter small grains breeder. “We had a tremendous amount of rainfall in December, January and February. Add in cold weather and we’re looking at poor tillering and a late crop.
“In a lot of fields — certainly in my nursery — nothing is headed out. The crop is probably two weeks behind normal. You can also see the ground between rows quite easily, something you shouldn’t be able to do.
“So, along I-10, the crop isn’t particularly good. Farther north, there was a bit less rain and the wheat crop looks a good bit better.”
For more on Harrison’s work, see Steve Harrison.
In Louisiana, stripe rust is “statewide, right now. It’s been reported from Bossier City to Winnsboro to Baton Rouge to Crowley. So, it covers the state.”
At this point, the rust “isn’t a big issue with growers. Whether it becomes a big issue, or not, I don’t know — it’s a little early to say. Certainly, we’ve had the consistent, cool weather that favors stripe rust.”
And there’s been enough moisture for stripe rust to gain ground, as well. However, “recent winds have prevented dews. Without free moisture stripe rust won’t move.”
Generally, though, “conditions have been good for stripe rust development. I expect it to continue moving for another a couple of weeks, at least.”
Harrison wasn’t surprised by stripe rust’s arrival. “If stripe rust is going to show up, we usually expect it in February. It’s a cool-season rust. I actually expected stripe rust this year given the uniform cool temperatures and moisture we had all winter.”
Even though it lurks close by, stripe rust still hasn’t been reported in Arkansas.
A mid-March rust alert was issued to Arkansas producers “because Louisiana and Texas researchers have reported widespread stripe rust in those states,” says Gene Milus, University of Arkansas professor and wheat pathologist. “Most of Arkansas’ stripe rust inoculum probably comes from Texas and Louisiana — especially in a year like this. Eventually, it will get (into Arkansas wheat). And since the wheat crop is behind, once established, stripe rust still has plenty of time to do some damage.
So, there’s no urgent problem in Arkansas at this time. Mainly, farmers need to know that stripe rust will be here soon.”
For more on Milus’ work, see Gene Milus.
In past years, “we did a good job of eliminating the very susceptible varieties when stripe rust was an annual problem. But I’m a bit concerned that someone may have planted a very susceptible variety thinking ‘well, we haven’t had stripe rust for a while and I can get away with this.’
“But very susceptible varieties have, basically, no resistance to stripe rust. A ‘susceptible’ variety still has some resistance when measured against a ‘very susceptible’ variety.”
If conditions are favorable for stripe rust, says Milus, “one well-timed fungicide application on a ‘susceptible’ variety will protect the crop from most losses. But you’ll need two fungicide applications to protect a ‘very susceptible’ variety. That’s a big difference.”
What about wheat acreage this year?
“Acreage everywhere is down,” says Harrison. “The entire eastern United States is down. It’s a rough guess, but I’d say no more than 75 percent of last year’s acreage has been planted. And last year’s acreage was already down from the previous year. That’s true across the region.”
Milus says the main problem with the wheat crop is “we don’t have enough of it. Acreage is way down. Interest in wheat seems to have waned a bit. Currently, it isn’t a money-making crop, which is the root of the problem. I can’t blame growers for not planting much wheat. I wish it would turn around and be more profitable, but carry-over stocks appear to be high worldwide and this will keep the price down in the short term. The most optimistic estimate I’ve heard is 200,000 acres planted. I’m also hearing some of the stands aren’t the greatest, and we probably won’t harvest 200,000.”
Several factors have compounded the problem, says Milus. “One is late-planting — most of the wheat out there was planted on the late side. Second, all the wet weather before and after the crop was planted meant the crop wasn’t able to get established well in the fall. A colder-than-normal winter made that situation worse.”
The wheat crop “is not as far along, or in as good a shape, as we’re used to. The crop is at least a couple of weeks behind where we’ve been in the last several years at this time.”
Any new varieties look promising this year?
“It’s really too early to tell,” says Harrison. “The crop is so far behind in terms of development. We’re just starting to get notes taken and walk the plots a lot.”
An LSU AgCenter field day will be held on April 8 in Winnsboro, La., starting at 9 a.m. For more information, call Wink Alison, who heads the Macon Ridge Research Station, at (318) 435-2157.
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