Hi, I'm so glad to have found this site because I have a fairly big hydrangea problem. We have a hydrangea 'hedge' growing in front of the trellis that encloses our front patio. It has been there for over 20 years and blooms faithfully every year. Four years ago I discovered that on several of the plants there were little "envelopes" formed by two opposing leaves. On opening one of the 'envelopes' I saw a tiny light green caterpillar and a few black specks (I presumed eggs). I removed them all summer whenever I found them. When I did not catch them, the stem wilted and died. I have struggled with them each year since, using BTK the last two years, but they have returned. I still get blooms, but I think they are smaller. Does anyone know what this is? Is it peculiar to hydrangeas (I don't have it on any of my other shrubs, trees, or perennials)? What can I do about it? Your help is greatly appreciated.
Thank you.
-
Northerner
- Full Member
- Posts: 15
- Joined: Wed May 19, 2004 1:27 am
-
The Helpful Gardener
- Mod
- Posts: 7491
- Joined: Mon Feb 09, 2004 9:17 pm
- Location: Colchester, CT
Hi
This is easier to diagnose than cure; leaf roller caterpillars aren't usually noticed until they start building their homes, homes which help protect them from sprays. BT only affects younger larvae and is not effective on them in the later stages (leaf rolling).
This is a problem you need to catch early in the year; pyrethrins applied while the young are still moving about is a good organic solution, but the key is getting them young (BT would also help at this stage, but I'd go for the direct kill). Systemic insecticides are another route, but less environmentally safe, and also less effective on chewing insects than sucking insects; I'd hit the little un's with pyrethrins. If they've started rolling already, start cutting off every one you can find and hopefully that will reduce or eliminate next years population...
Good luck,
Scott
This is easier to diagnose than cure; leaf roller caterpillars aren't usually noticed until they start building their homes, homes which help protect them from sprays. BT only affects younger larvae and is not effective on them in the later stages (leaf rolling).
This is a problem you need to catch early in the year; pyrethrins applied while the young are still moving about is a good organic solution, but the key is getting them young (BT would also help at this stage, but I'd go for the direct kill). Systemic insecticides are another route, but less environmentally safe, and also less effective on chewing insects than sucking insects; I'd hit the little un's with pyrethrins. If they've started rolling already, start cutting off every one you can find and hopefully that will reduce or eliminate next years population...
Good luck,
Scott