Onion thrips and corn leaf aphid populations
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included
Onion thrips populations remain high in many onion fields due to the high temperatures. (view image) Numbers are decreased somewhat, but heavy rainfall, but can quickly rebound. Carzol appears to be working well to control thrips (See the July 19 issue of the Vegetable CAT Alert.).
We have received reports of high populations of corn leaf aphids in sweet corn. Corn leaf aphids are about a sixteenth of an inch long, blue-green and have short black cornicles (“stovepipes”). Like other aphids, females give live birth to offspring (all of which are also females) without fertilization. Also, like other aphids, populations can build very rapidly, especially in hot weather.
High corn leaf aphid populations can reduce yield in drought-stressed plants. Of more significance is the honeydew they produce while feeding. The honeydew accumulates on the plant and promotes the growth of sooty mold. Sweet corn growers should scout their fields and treat when populations start to build. See Bulletin E-312, 2006 Insect, Disease and Nematode Control for Commercial Vegetables. This bulletin can be viewed at http://veginfo.msu.edu