Improved fungicides can be a plus for producing higher-yielding wheat

By most accounts, this has been a difficult spring for farmers growing wheat in Louisiana. Excessive rain – 16 to 18 inches in recent weeks – has delayed harvest and reduced yields and test weights across most of the state.

When LSU’s Steve Harrison spoke at the Macon Ridge Research Station Wheat Field Day on April 22, most of the problems were still ahead of producers, and Harrison was able to focus on what growers could do to improve wheat yields.

One of the steps producers can take is to apply a standard fungicide on their varieties, preferably varieties that are bred specifically for their locales with the latest yield enhancements contained in them, according to Dr. Harrison, who has been working as wheat and oats breeder for the LSU AgCenter for 30 years.

It’s a fairly new practice for Harrison. “Ten years ago the fungicides weren’t that good,” he said. “They would control loose smut and maybe a few seedling diseases, but in the last 10 years systemic fungicides have gotten so good. They can bump germination up a lot. They can give you a little bit of fall leaf rust establishment control and other things. So they make a difference.”

Harrison asked Jimmy Clements with AgSouth Genetics for his take on fungicide and insecticide seed treatments. Clements, based in Albany, Ga., has been working with wheat for most of his career.

“We like whatever fungicide the grower wants on the seed,” said Clements. “We don’t try to push them. We like to see seed with a fungicide and an insecticide. We have a pretty severe problem with aphids in the winter time. In December, we still have temperatures running in the 35- to 40-degree range. The aphid population will bloom at that time so we like to put an insecticide on the seed.”

Staying power

Clements said fungicides can help wheat “sit a little longer in wet, cold soils and still germinate and give you a good stand. So we really try to put fungicide on as much grower seed as we possibly can.”

Applying a fungicide and an insecticide can cost about $6 per 50-pound bag of seed, says Clements. “We think it’s worth it because it gives you the stand you need for a good yielding population.”

Harrison also cautioned growers against trying to save money on seed costs by planting saved seed of varieties that might have been top yielders 10 or 12 years ago.

In fielding calls about the outbreak of Fusarium head blight or scab that invaded a number of Louisiana wheat fields this past spring, Harrison said he frequently encountered growers who were planting saved seed.

“While I’m preaching and before we get started on the variety trials, I’ve gotten a lot of calls about the scab that Boyd (Padgett) is going to talk about,” he said. “The calls are to the effect of ‘if I put out a $25-per-acre fungicide treatment will it help any? And the answer is no.

“But if we go a little further about what growth stage they are, what variety did you plant, what’s your management, and the story comes out that it’s saved seed; that the grower has been saving this seed for six years because he liked it. It’s a 12-year-old variety that probably has a 20-percent yield penalty.”

Savings offset

The upshot is the grower has saved $15 up front and cost himself $60 to $80 on the back end,” says Harrison. “Don’t do it. If you’re going to grow wheat, manage it like a crop. And I’m through preaching.”

2015 proved to be a difficult season for growers and scientists alike.

Calling it a season “full of challenges,” Harrison said the weather created a good environment to evaluate and select breeding lines as well as commercial varieties, particularly to find those with good resistance to diseases and environmental stresses.

Dr. Harrison cited three factors that created particular challenges.

First, he said, spring rains created significant levels of leaf diseases – both bacterial and fungal.

A late freeze caused stem damage, which caused plants to fall over, or lodge. The earliest-maturing varieties were hardest hit, he said.

The major problem for growers was a week of rain during wheat flowering, Harrison said. This led to very high incidences of Fusarium head blight or scab.

“The average grower probably lost 30 percent of yield and crop value to Fusarium,” he said. “Some fields yielded virtually nothing.”

Fusarium head blight is a difficult disease to manage because no variety has complete resistance, Harrison said. Fungicides need to be applied within a window of a week to 10 days from the start of flowering. “But fungicides cannot be applied during rain, so there’s a Catch-22,” he said.

The AgCenter Baton Rouge wheat breeding nursery was particularly hard hit. A late-April storm leveled the nursery plots, and Harrison’s crew had to resort to hand-harvesting to collect enough seed for trials next year.

Other cooperators in the Sungrains consortium of Southern university wheat breeders also had weather problems. But the University of Arkansas and Georgia plots had less bad weather, so the AgCenter program will be able to harvest enough seed from those sites to plant for next year’s yield trials and increases.

For more on wheat research and wheat diseases in Louisiana, visit http://www.lsuagcenter.com/en/crops_livestock/crops/soybeans/Soybean+Grain+Promotion+Board+Reports/Wheat+breeding+program+breaking+new+ground.htm

 

TAGS: Management
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