Aflatoxins, Spider Mites Pose Concern to Missouri Crops

By CnAgri2012-07-30 19:57:39 Print

Fields six miles southeast of Lamar were scouted by Wyatt Miller, an agronomy assistant with University of Missouri Extension in Barton County.

Corn scouted this week was between dough and dent stages. Because of the drought significant yield losses are expected in several fields. Some producers may consider using corn as forage for livestock.

"We encourage producers to get a quantitative lab test for nitrates with drought stressed corn. Those who will be harvesting corn should be aware of the potential for Aflatoxin in corn," said Miller.

Aflatoxins are generally caused by Aspergillus, which is typically associated with drought stress and evident as a greenish yellow to mustard-yellow mold growth on the ear.

Soybeans scouted this week were between stages v-6 to R-2, full flowering. Some grasshoppers were seen this week under threshold levels; treatment is justified when defoliation reaches 30 percent before bloom and 20 percent between bloom and pod fill.

"Drought conditions have reduced most insect populations, but have increased the chance for two-spotted spider mites. Some spider mites were found this week under threshold levels," said Miller.

Producers should scout for spider mites near the edge of fields on yellow speckled leaves near grassy boarders or gravel roads. When scouting, shake infested leaves over white paper and look for small yellow mites crawling.

Spider mites are very small, yellow-green to red, and best seen using 20X magnification. 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.