Knowledgebase
Knock Out Roses “disease” #873067
Asked June 14, 2024, 7:52 AM EDT
These rose leaves have been decimated by something although we have not seen any pests. And they are still blooming.
From the diagnostic sheet: plants are 10 years old; condition first noticed around May 25, 1924; they are in good drainage; hot weather at the time with lots of rain; they are in full sun; no fertilizer, pesticides or weed killer used; no pest seen; image attached. Please suggest treatment.
Chittenden County Vermont
Expert Response
Good Morning Janet,
Thank you for contacting UVM Extension Master Gardener with your question. This appears to be Rose Slug, a type of sawfly larva. More information can be found at the below Missouri Botanic Garden site which includes some integrated pest management (IPM) strategies:
I've also included some additional extension sites on rose slug/sawfly below, some of which also recommend treatment strategies:
https://hort.extension.wisc.edu/articles/roseslug-sawfly/
https://content.ces.ncsu.edu/roseslug-or-rose-sawfly
https://yardandgarden.extension.iastate.edu/encyclopedia/rose-sawfly-roseslug
Thank you,
