My McIntosh apple trees have what I think are leaf rollers who have devoured the blossom buds. What can I use to get rid of the leaf roller worms? I've heard that Bt might work. What is Bt and will it be effective? If not, what works?
Attached is a link that explains what Bt is better than I could. Just make certain that your pest is a caterpillar, and that you purchase the strain of Bt that is specified for caterpillars. Bt-k is what you are looking for.
Here is a link that might be useful: Bt