What is in this article?:
- Aflatoxin still a concern for Southeastern corn growers
- Goes out at tasseling
- Less kernel damage
• You want the corn to mature before the temperature hits a sustained 95 degrees F. in the afternoon.
• Temperatures must get really high for the fungus to produce toxins.
PLANT STRESS DUE to drought, heat or insect damage during fungus growth usually increases aflatoxin levels in corn.
Goes out at tasseling
“This is the second year we’ve looked at Afla-Guard. It’s applied over-the-top, and you’ll need a high-boy with a spreader on it or large spreader unit. It goes out as the corn goes into tasseling, hopefully right before a rain.
“It’s a grain product that basically is impregnated with spores of a non-toxic producing strain of aflavus.”
The idea behind the product, he explains, is that you put it out prior to the time the silks are infected by the fungus. The Afla-Guard fungus will sporulate on the ground and in the canopy, and those will be the first spores that get to the silks, he says.
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“So they will be the ones growing on the silks, and when the toxin-forming ones show up at about the same time, they’re excluded — it’s an exclusionary system.”
In a test conducted at the Wiregrass Substation in 2011, Hagan planted several different Bt-trait varieties.
“In that test, we didn’t see any effect from Afla-Guard on any of the variables we were looking at, and we also didn’t see a reduction in aflatoxin in the treatment.
“In the variety trial next to it, where we used Afla-Guard and a non-treated control, it looked like there was a reduction in several varieties in the trial. So it looked like we had a little less aflatoxin in the treated compared to the non-treated.
“One of the problems we run into in working with aflatoxin is that there’s a lot of variability from sample to sample that we pull out of these plots.
“It’s really difficult to show differences or suppression of aflatoxin with some of these treatments, and that has been an ongoing problem with some of our trials.”
The base genetics of a lot of corn varieties differ in their sensitivity to aflatoxin, says Hagan.
“That information hasn’t been generated to any degree for the varieties we grow down here. We simply don’t know which ones might have less toxin accumulation than others.
“In the statewide variety trials, we’re pulling kernel samples from most varieties in each of the trials, and we’re specifically looking for information as it relates to Bt traits.
“Some varieties seem to have more alfatoxin than others in the areas where the fungus occurred. But there’s still a lot we don’t know about these varieties.”
Hagan is also looking at the timing of Afla-Guard treatments. “Basically, when we pulled out the aflatoxin contamination levels, there were no differences among these treatments.
“On the Gulf Coast, we didn’t have much aflatoxin contamination on corn. The timing appeared to have an impact on insect damage from corn earworm in ears, but it really didn’t affect anything else, and it didn’t affect the yield.”
A test from Oklahoma showed that Afla-Guard does reduce aflatoxin, says Hagan. When they put it out early, there was no effect. But at V9 through VT, in three of the four timings, there was a substantial reduction in the amount of aflatoxin in corn. However, the numbers were still high, he says.