Knock off Rose bushes - Ask Extension
Can you tell me what is happening to my knock off roses. They have been this way since early spring
Knowledgebase
Knock off Rose bushes #877646
Asked July 17, 2024, 2:09 PM EDT
Can you tell me what is happening to my knock off roses. They have been this way since early spring
Alpena County Michigan
Expert Response
Good Morning,
The damage on your rose bush appears to be from roseslug sawfly larva. Leaf blotches during May and June are a telltale sign or symptom of the roseslug Sawfly. During the months of May and June you may have noticed leaf discoloration in the form of blotches on your rose leaves. If you inspect the undersides of the leaves closely you will see the culprit! It is a small, narrow-bodied larva called the roseslug sawfly. The larvae have pale green colored bodies and light tan-orange colored heads.
It's important to identify the pest to determine proper control measures. You'll want to look on the stems and on the undersides of leaves for any insect pests. Sometimes they blend in quite well with the leaves. There are a few pests that are common for roses including with more common ones being japanese beetles and rose sawfly this time of year. I'm including some links so you know what to look for.
https://www.canr.msu.edu/resources/slug_sawflies
https://extension.umn.edu/yard-and-garden-news/managing-japanese-beetle-feeding
Rose and pear slugs (sawflies) (missouribotanicalgarden.org)
What’s Eating My Roses in Spring? — Sawflies - Insect Diagnostic Lab (wisc.edu)
Spraying the larvae with horticultural oil or insecticidal soap will kill the larvae. Complete larval coverage is necessary for effective kill. Horticultural oil (light weight) suffocates insect larvae, has a residual of a few days, and has very low mammalian toxicity (Ball and Ball, 1989). Insecticidal soaps are commercially formulated contact insecticides of low mammalian toxicity and designed to biodegrade in the environment within one to two weeks (Ball and Ball, 1989). Additional, using a garden hose to spray the larvae off the leaves with a strong water flow also works well. The larvae, once knocked off the host plant are incapable of climbing back up onto the leaves to resume feeding (Johnson and Lyon, 1991).
You can submit a sample for a small fee to verify the pest/disease.
Submit Samples - Plant & Pest Diagnostics (msu.edu)
I hope this helps. Thanks for using our service.
The damage on your rose bush appears to be from roseslug sawfly larva. Leaf blotches during May and June are a telltale sign or symptom of the roseslug Sawfly. During the months of May and June you may have noticed leaf discoloration in the form of blotches on your rose leaves. If you inspect the undersides of the leaves closely you will see the culprit! It is a small, narrow-bodied larva called the roseslug sawfly. The larvae have pale green colored bodies and light tan-orange colored heads.
It's important to identify the pest to determine proper control measures. You'll want to look on the stems and on the undersides of leaves for any insect pests. Sometimes they blend in quite well with the leaves. There are a few pests that are common for roses including with more common ones being japanese beetles and rose sawfly this time of year. I'm including some links so you know what to look for.
https://www.canr.msu.edu/resources/slug_sawflies
https://extension.umn.edu/yard-and-garden-news/managing-japanese-beetle-feeding
Rose and pear slugs (sawflies) (missouribotanicalgarden.org)
What’s Eating My Roses in Spring? — Sawflies - Insect Diagnostic Lab (wisc.edu)
Spraying the larvae with horticultural oil or insecticidal soap will kill the larvae. Complete larval coverage is necessary for effective kill. Horticultural oil (light weight) suffocates insect larvae, has a residual of a few days, and has very low mammalian toxicity (Ball and Ball, 1989). Insecticidal soaps are commercially formulated contact insecticides of low mammalian toxicity and designed to biodegrade in the environment within one to two weeks (Ball and Ball, 1989). Additional, using a garden hose to spray the larvae off the leaves with a strong water flow also works well. The larvae, once knocked off the host plant are incapable of climbing back up onto the leaves to resume feeding (Johnson and Lyon, 1991).
You can submit a sample for a small fee to verify the pest/disease.
Submit Samples - Plant & Pest Diagnostics (msu.edu)
I hope this helps. Thanks for using our service.
