Insect update for July 15, 2011

Be on the lookout for a spider mite outbreak while the weather is dry. Also, the brown marmorated stink bug still has yet to make an appearance in Michigan.

Spider mites

Many areas are dry, making perfect conditions for a mite outbreak. Mite damage (yellowing) tends to be seen first on lower leaves along dusty edges of fields. Mites are often kept in check by fungal pathogens, but these diseases can’t take hold under dry conditions.

Corn Rootworms

Adult beetles are emerging. Rootworms and Japanese beetles can combine to clip corn silks. As with western bean cutworm, these insects may accumulate in more mature fields that silk first. Threshold - fresh silks (not yet pollinated) pruned to within 6 inches of the husk.

Soybean aphids

Numerous beneficial insects are out there in soybeans.  Please don’t add insecticide to herbicide or fungicide applications for insurance, especially given the risk of spider mites.

Brown marmorated stink bugs

No brown marmorated stink bugs found so far by the MSU fruit and vegetable labs trapping for this new pest. It’s just not an issue yet!  However, if you want to see the impact that brown marmorated stink bugs have on soybeans in the eastern United States, my colleague Ames Herbert, a stink bug guru from Virginia Tech, recorded a great webcast discussing brown marmorated stink bug injury, biology, and management. See the website at Brown Marmorated Stink Bug: A Confirmed New Pest of Soybean.

Dr. DiFonzo’s work is funded in part by MSU‘s AgBioResearch.

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