Corn insects we may see in July are European corn borer and new to northern Ohio the Western bean cutworm. See your Corn, Soybean, Wheat and Alfalfa Field Guide for images and scouting suggestions.
If you are in continuous corn, watch for Western corn rootworm. This pest has reappeared in areas of the central cornbelt in continuous corn situations, apparently overcoming the Bt insect protection trait. Entomologists say the breakdown of this insect protection trait was expected. Let us know if you see unexpectedly lodged corn.
Soybean aphids were a surprise to many of us last year in central to west central Ohio. From past experience, 2015 is expected to be an “aphid year” so plan to scout for this invasive pest. Typically we hear reports in northern Ohio about July 1 and to central Ohio about August 1. See the Field Guide for recommendations on aphid speed scouting.
Last year we had northern corn leaf blight and gray leaf spot begin to appear by early July. If you are dry this isn’t likely to occur, but if soils are wet then yes you may see the beginnings of disease. From our corn pathologists these factsheets will help: http://ohioline.osu.edu/ac-fact/pdf/0020.pdf and http://ohioline.osu.edu/ac-fact/pdf/0038.pdf. The concern in soybeans, once we get past emergence problems, is Frogeye leaf spot. We have too many bean-on-bean acres so look for this disease and read these comments from Anne Dorrance: http://ohioline.osu.edu/ac-fact/pdf/0053.pdf.
Watch the Crop Observation & Recommendation Network newsletter for reports of disease and insect appearance across the state: http://corn.osu.edu.