Aflatoxin Found in Missouri Corn, Spider Mites in Soybeans

By CnAgri2012-08-13 19:50:57 Print

Fields in Barton County, northwest of Iantha, were scouted by Wyatt Miller, an agronomy assistant with University of Missouri Extension in Barton County.

"Several ears were found this week with Aspergillus ear rot, which typically causes aflatoxin. Aspergillus flavus is generally associated with drought stress and evident as a greenish yellow to mustard-yellow mold growth on the ear," said Miller.

Mold growth is optimum at 18-20 percent moisture and can continue after harvest until moisture level is 13 percent or lower.

Those concerned with aflatoxin contamination should consider selling to elevators with grain intended for finishing livestock. The maximum acceptable level for aflatoxin in corn for finishing feedlot beef cattle is 300 bbp, while only 20 bbp for corn intended for human consumption.

"Soybeans scouted this week were between V-7 and full bloom. Several soybean podworm moths, also known as corn earworm moths, were seen this week. Producers should begin scouting for soybean pod larvae," said Miller.

Larvae can be several colors, but can be distinguished by four pairs of large abdominal prolegs in the center of the body. Treatment is justified when defoliation reaches 30 percent prebloom or 20 percent from bloom to pod fill, or when larvae exceed one per linear foot of row and 5 percent or more of pods are damaged.

Two spotted spider mites were also seen and treatment is justified when foliage yellowing reaches 20 percent and mites are present on plant before pod set, or when foliage yellowing reaches 10 percent after pod set.

Soybean yields will be determined by the next few weeks. Those who are considering using beans as forage should check with their crop insurance adjuster and check pesticide labels for harvest restrictions before doing so.

Estimated tonnage for hay ranges from 2 to 4 ton/acre with removal rates of approximately 10 lb phosphate, 25 lb potash, and 45 lb of nitrogen per ton.