Not just because the leaf is folded. But if lots of the leaves in one stem are unable to produce the necessary amt of food for the stems due to damage (ie, photosynthesis is impaired greatly), the plant might decide to stop flower production in that stem.

Flowers and flower buds are the first to go when the plant is stressed from lack of water, etc so if many leaves are turning dark/ugly green, yellow or brown due to damage from the leaf rollers, s-o-m-e stems might not bloom.

http://hyg.ipm.illinois.edu/article.php?id=359

Thanks, Luis!

I had a bunch of LR this year (first time I noticed them), but most just seemed temporary and the stem growth simply powered through and around the sets of two leaves affected, whilst producing flower buds simultaneously.

I thought it was neat more than anything, how the two topmost leaves would be nearly stitched together by some type of secretion, to the point where you not even open the pouch without tearing the leaves.

As for prevention, the only thing I could think of would be to remember to spray insecticide in early May.

Ruth, in my experience the leaves affected by leafroller will wither and fall off, and not affect bloom too much. But I do think for the long term health of the plants it's better not to ignore it. I have two Annabelles that get leafrollers every spring. I go through and pick off as many of the affected leaves as I can. If you have many it may be hard to get them all, but at least the leafrollers are only at work for a few weeks. You want to try to stop the cycle in future years (since the caterpillars will drop to the soil to pupate and get ready for next year). Insecticide is really difficult to time because there's such a brief window when they aren't inside the leaves.