Answer: Unfortunately, black knot of plums and cherries is a difficult disease to control. This fungus spreads quickly from wild trees to cultivated ones. The first step is to remove any wild trees from the area and destroy them. ones the fungus is on the tree, the only cure is to prune it off and destroy the branch. Make cuts at least 6" below the infection and disinfect the pruners between cuts by dipping them in a 1% chlorox solution. There aren't any effective sprays around to control this disease, so good sanitation by removing and destroying infected branches, picking up old fruits and dropped twigs and destroying them is the best bet. Don't compost or burn the branches because that will just spread the disease more.
Q&A Library Searching Tips