A lesson on plant bugs and leafhoppers

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.  

Four-lined plant bugs

I’m not sure if it is the moist spring or what, but we are getting lots of calls about tan-colored or purplish circular spots on the leaves of perennial geraniums, mums and ‘Limelight’ Hydrangea. These are the symptoms of feeding damage caused by the four-lined plant bug. The bug itself is quite attractive, a brilliant yellow-green color with four black lines running the length of its body. When it sticks it needle-like mouthparts into a plant to suck juices, it also injects a small amount of saliva that is toxic to the plant, leaving a tan or purplish, circular spot. The spots are so circular, that they are often mistaken for a plant disease. I expect the damage from four-lined plant bug to be about over for this year, but if you are still seeing the bugs themselves, plants can be protected Sevin or a pyrethroid insecticide.

Leafhopper damage to burning bush in nurseries

This problem was brought to my attention by Tom Dudek, a district horticulture educator in west Michigan. Burning bush shrubs in some fields are showing typical “hopper burn” damage, where leaves turn purple and the leaf tips and leaf edges turn brown as a result of leafhopper feeding injury. The culprit is usually the potato leafhopper, and the damage is most notable on red maples. However, watch burning bush this summer for these symptoms, and look for the tiny (3 mm-long) green leafhoppers on the undersides of the leaves.  

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

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