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knock out rose bush defoliation #872521

Asked June 10, 2024, 8:46 PM EDT

we have dealt with Japanese beetles destroying our knock out rose bushes but this season the beetles haven't arrived but something else (too small to see) is defoliating our rose bushes. Is this a mite? Any recommendations? thanks

Story County Iowa

Expert Response

Without a photo it is a bit hard to say what is going on.  However, speculation is as follows:  The most common cause of rose defoliation is caused by rose slugs (a type of sawfly related to wasps); they may have already come and gone leaving their damage behind.  If any were to remain, scouting at night would make them easier to spot.  

Caterpillars and sawflies cause damage by feeding on the leaves, resulting in leaf skeletonization or defoliation. Severe defoliation is unsightly and can interfere with plant growth.
https://extension.msstate.edu/sites/default/files/topic-files/flower/pest-of-roses.pdf
http://cues.cfans.umn.edu/old/extpubs/6953rosepests/6953_01.html
Answer Line answer@iastate.edu Iowa 800-262-3804 and Minnesota 800-854-1678 Replied June 11, 2024, 2:54 PM EDT

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