Question: I have several cotoneaster plants that have suddenly developed dead branches. What causes that? I find no insects, and the branches have not been broken.

Answer: That’s probably fire blight, a very serious disease of all cotoneasters. These plants are in the rose family, and this disease of that group of plants will make isolated limbs look like they have been burned with a blow torch. Prune them out, cutting back into healthy wood. Disinfect your pruning tools with a 10-percent chlorine bleach solution between each cut. Spray while the plants are in full bloom in the spring with agricultural streptomycin.