Early summer heat curtails the impact of grain disease, but research moves forward

The unusual late spring, early summer heat wave combined with dry conditions have lessened the severity of soybean and grain disease this year — a far cry from last year’s rain-drenched season. Yet, according to LSU AgCenter pathologists Boyd Padgett and Trey Price, the weather hasn’t slowed down the research that both are currently conducting on behalf of growers.

“A lot of these fungal organisms need moisture for the spores to germinate, and in fact we haven't had that this year,” Padgett said in June. “I mean, it was 100 degrees just the other day.”

Padgett says that there have been a few occurrences of aerial blight, but it is nothing compared to the growing season of 2021. To keep the research robust, his team has been planting susceptible varieties to test the efficacy of commercial and experimental fungicides.

“We also evaluate the impact fungicides have on different varieties,” he said. “We have evaluated as much as 125 different varieties in five different maturity groupings in the official variety trials.”

Padgett went on to say that his team planted two official variety trials at two locations: Alexandria and Baton Rouge. One trial was treated with a fungicide and the other trial was not treated, which provides stakeholders with variety performance with or without a fungicide.

“The applications are triggered by the growth stages of the plants, so when the different maturity groups start developing tiny pods, we’ll put the fungicide application out,” he said.

Padgett’s colleague Trey Price currently has three projects that the AgCenter is conducting. In addition to soybeans, he is also researching diseases affecting corn and wheat. For the corn project, Price is working in a continuous corn, no-till field, which he says increases the chances of naturally occurring foliar disease.

“Producers can use our information to make decisions on which varieties they want to plant the following year,” he said. “From an agronomic standpoint, that continuous corn information may be helpful to a lot of growers that plant continuous corn.”

Like Padgett, Price says the hotter, dryer June weather has adversely affected the foliar diseases in his plots, calling them “practically nonexistent.”

“It’s been a very clean corn crop this year, and that’s mainly due to the dry weather,” he said. “Most of these foliar diseases in corn are driven by frequent rainfall.”

As far as soybeans go, Price is continuing to work on salt-tolerant varieties, which is important to producers in and around northeast parishes where the Macon Ridge Research Station is located. There, groundwater salinity is high.

Price said his researchers rate soybean varieties on a zero to nine scale, where zero means the varieties are invincible to salt and nine means they will surely die. He says many fall in the middle. Those with higher tolerance are called excluders.

“It may not be a zero, but a four, five or six,” he said. “When planting soybeans marketed as excluders, growers need to know to what extent they are effective, which is the main purpose of our trial.”

In addition, one disease Price and his team are currently looking at is taproot decline (TRD) with a specialized variety screening at Macon Ridge, where there appear to be TRD-resistant commercial varieties farmers can use. He says there are a few promising seed treatments for managing the disease, but the researchers don’t have solid recommendations yet.

“Growers would rather be able to use a seed treatment, which is much more convenient for them instead of in-furrow fungicide applications, so we are continuing to look at that,” he said. V. Todd Miller

8/17/2022 8:54:06 PM
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