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.
Less kernel damage
“At this point in time, from the different Bt II traits, we’re seeing less kernel and silk damage and some yield gains in some years, but that’s not resulting in a reduction in aflatoxin.
“So we’re not seeing an association between advanced Bt traits and less aflatoxin in corn, and there’s still a lot of work to be done on Afla-Guard to see how consistent it is in reducing the amount of aflatoxin on corn.”
Proline fungicide actually has a label for aflatoxin suppression in corn in the Midwest, and as far south as Arkansas, says Hagan.
“We should get the opportunity to add that label in Alabama. We don’t know if this treatment will work on aflatoxin, but we’ll be looking at it this year.”
Hagan says there have been a few concerns about Northern corn leaf blight on corn in Alabama.
“There are differences in sensitivity among corn varieties to the disease. On some varieties, the leaf spots will be about 2 or 3 inches long, while they will be about 18 inches long on another variety.”
Northern corn leaf blight doesn’t have the same effect on yields — particularly on early corn — that Southern corn rust can have, says Hagan.
“To really reduce yields in corn, Northern corn leaf blight has got to take out the ear leaf, and I haven’t seen many situations on early corn where that has occurred.
“If you plant double-crop corn, or corn after wheat, then all bets are off. It’s very active in double-cropped corn. The best defense is to plant early.
“Once we get into wet weather patterns in June, you could be in real trouble. Wet weather really drives foliar diseases in corn, and Northern corn leaf blight will be more severe in late-planted corn.”
Several new corn fungicides are on the market, including Evito T, TopGuard and Priaxor, says Hagan.
“In the trials we’ve done on early corn where disease pressure isn’t that great, there really isn’t a lot of difference between the generic products and the name-brand materials.
“But when you get into double-cropped corn or when you have severe rust, the name-brand products do a much better job of protecting corn, and we tend to see a higher yield gain with those products compared with generics.”
If you have reniform nematode, corn is great for rotating with cotton, says Hagan. It fits well, and it’ll knock down any reniform nematode problems.
“However, we run into problems when we have root-knot nematodes. If fields have root-knot nematodes with cotton, it’ll jump onto corn and will reduce yields substantially.
“You don’t get the stunting you sometimes see with other nematodes in corn, but in trials we’ve seen that corn dries down faster and yields are reduced.”
Materials like Mocap and Counter applied as a granular treatment in-furrow will not only suppress nematodes, but will have activity against insects, says Hagan.
“The other options are seed dressings that also are labeled for nematode suppression in corn.
If you’ve had a lot of root-knot nematodes in the field, and you’re in a corn/cotton rotation, it would help to put peanuts in the rotation to suppress nematodes and bring up yields on corn and cotton.”
You might also like