The objective of my research is to determine the best ways of integrating pesticides, biological information on pathogens, genetic resistance to diseases, and IPM techniques into cost-effective and environmentally sound pest control strategies for tree fruit crops. My annual field evaluations of fungicides provide apple growers with some of the information they need to control apple diseases at the lowest possible cost. Apple pathogens included in my studies are Botryosphaeria species that cause summer fruit decays, Colletotrichum species that cause bitter rot, Zygophiala jamaicensis, the cause of flyspeck, and Penicillium species that cause postharvest decays of apples. For the past six years, I have conducted extensive research with Penicillium expansum, a fungal pathogen that causes apple decays during storage. Our research has shown that the Empire variety is especially susceptible to decay because P. expansum can invade Empire fruit by growing down through the length of the stems during long-term storage. Susceptibility to invasion through stems is positively correlated with increasing levels of boron in leaves. At the same time, we have shown that inoculum for P. expansum in apples recycles from year to year on the bulk bins that are used to store fruit after harvest. Methods for disinfesting bins are being evaluated. Disinfesting bins could provide an effective means for reducing losses during storage.