Louisiana is in the process of harvesting 400,000 acres of “pretty good” wheat. “There was a lot of rainfall after planting and that certainly reduced tillering in some fields,” says Steve Harrison, LSU AgCenter small grains breeder. “We had a fairly dry spring.
“There was not a lot of stripe rust pressure. We had more leaf rust than has been seen in a few years — in some fields it was a rather large issue.”
The most unique thing that hit Louisiana wheat this year was Hessian fly. Significant problems with the pest occurred along I-10 in central Louisiana and in scattered fields throughout the state.
“It appears to be mostly related to planting soybeans reduced-till after wheat and then returning to wheat the following year. That pattern — along with favorable weather for the pest — allowed Hessian fly populations to build.
“The initial source of a Hessian fly infestation is dormant pupa that oversummer in old wheat straw and hatch out when temperatures cool off in the fall. Reduced tillage with wheat following wheat/soybeans provides a favorable environment for Hessian fly to survive in a dormant state over the summer.
“Hessian fly is something we'll probably have to address in the future. That's something that hasn't been a problem in the past.”
There are five options to control Hessian fly.
- Delay wheat planting
“The cooler it is when you plant, the less active the fly will be. The fewer eggs laid in the fall, the smaller the Hessian fly problem will be in the spring since the population hasn't been building.”
Louisiana doesn't have a “true fly-free date like they do in the Carolinas, for example. I still believe that later planting provides less opportunity for egg-laying in the fall.”
“Don't plant reduced-till soybeans behind wheat followed by more wheat. You need to break that cycle, plow the residue down.”
- Deal with volunteer plants on field edges prior to planting
“Volunteer plants serve as reservoirs for Hessian fly. Clean the edges of fields up in early fall.
- Seed treatments
Seed treatment with some systemic insecticides can provide fall control of Hessian fly.”
- Plant resistant varieties
This is the best control option. Unfortunately, there are six or eight biotypes of Hessian fly and we're not sure of the biotype in Louisiana yet. We're waiting to hear back from the USDA Hessian Fly Lab at Purdue and should know some time this summer what the biotype spectrum is.
“We do know that not all varieties were affected by Hessian fly this spring and there is some genetic resistance available.”
This year's large wheat acreage in Louisiana is partially “responsible for developing some of these problems — more wheat behind wheat.”
Harrison suspects all the wheat acres will be double-cropped with either soybeans or “on a good number of acres, cotton. And, if it's minimum-tilled, the Hessian fly doesn't really care what's planted behind wheat. If wheat stubble is left that has fly pupae in it, the second crop's canopy and summer weather helps them survive.”
And fair warning: returning with minimum-till wheat this fall will mean “the Hessian fly will be extremely happy.”
During the season, leaf rust built to “rather high levels. It appeared some of the varieties that had reasonable resistance against it didn't do as well against it this spring.
“I'm not sure how many fungicides went out in the state. There were some, though, because we planted many varieties last fall we normally don't. That was due to seed shortages.”
Harrison is “sure” Louisiana's crop was impacted due to the unfamiliar or non-adapted varieties. Because of fungicide treatments, “it's made management more expensive on varieties that weren't first-choice.”