Wednesday, March 14, 2012

FAQ: Why does my Manhattan Euonymus have yellow spots?

"I have a hedge of Manhattan Euonymus that gets unhealthy yellow spots on the leaves every year. Why is this?"

Turning the leaves over, you may well find little flat whitish jobs on the underside. You’ll be looking at the males of Euonymus Scale. The brownish females are lurking nearby on the stems. This is an extremely common pest of euonymus. The scales suck sap out of the leaves, producing those lighter spots. Severe infestations can produce a lot of leaf drop. The pest doesn’t often kill a plant as vigorous as Manhattan euonymus, but it can make it pretty ugly.

The most effective sprays are horticultural oil, which suffocates the insect, and insecticidal soap, which kills by destroying the insects’ protective covering. Complete eradication is difficult as it’s almost impossible to cover every surface of the plant. In desperate cases, heavily infested branches can be cut out and destroyed, or the entire plant can be cut down and allowed to resprout if it’s not too late in the season.

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