Many of our clients at the Plant Clinic have apple trees in their landscapes and questions on disease problems. The major diseases encountered on apples this year were cankers, scab, fly speck, sooty blotch, powdery mildew, rust, fire blight, and black rot. Pruning is one of the most important cultural methods to help prevent many of these diseases. Although it is probably slightly better for tree health to prune apple trees in March, it is easier to do a good job as soon as the fruit crop is removed. Healthy plant material is more easily distinguished from dead or cankered wood in the fall. Pruning and removing dead and cankered wood and opening the tree to better air circulation limit the development of fire blight, black rot, sooty blotch, fly speck, and scab. If you suspect that fire blight was present in your tree, disinfect the pruners after every cut to prevent further spread of the pathogen. We recommend rubbing alcohol or a 10 percent solution of chlorine bleach as disinfectants, but other products may work as well.