My Plum tree has a very, very bad problem with catipillars, and I saw the post on "sick plum tree" but wasn't sure what the Btk spray is. Any help apreciated, Location of th tree, PA, Northwest corner of property. Thanks
Most sprays with catapillars are for before they hatch, once you see the "tents" you need to get them out of the tree (pruning works.) We burn the tents, as they catapillars make there way back. Once they are migrating off the tent, dealing with them is tough. 'pick em' off and 'squish' works, there might be a pesticide that you can use, but you'll need to check that with the local nursery. In the fall and the end of winter is when we spray with copper sulfur, before any sign of green.
copper is usually for fungal issues rather than insects. Btk is a product that you mix with water and spray to eliminate caterpillars. available at most garden centers.
Burning the tents can be counterproductive, as it destroys the branch beneath - something the caterpillars will never do.
Perhaps I should clarify, the burning is done to the caterpillars after I prune them out, I don't burn them up in the trees. Otherwise they crawl back up the tree.