Our research includes investigations on the biology, ecology, epidemiology, and management of diseases on tree crops grown in California. Specifically, our research focuses on the epidemiology and management of foliar diseases caused by fungal and bacterial tree pathogens. Research includes mycology, ultra-structure of host-pathogen relationships, biology of wood decay fungi, biological and molecular techniques for the detection and identification of fungi, and development of innovative management practices for pre- and postharvest disease control of fruit crops. We have developed exciting new strategies for the identification, detection, and management of pre- and postharvest diseases of tree fruit using reduced risk fungicides and disease forecasting programs in California. Recent advances include: Sampling and detection strategies of Septoria citri, causal agent of Septoria spot of citrus. Epidemiological and mesoclimate forecasting model for Septoria spot. Introduction of three new postharvest fungicides for citrus and a forth one pending; two new postharvest fungicides for pome fruit; and three new postharvest fungicides for stone fruit. Development of sanitation and fungicide treatments against sour rot of peaches and nectarines. Forecasting Alternaria leaf spot of Almond using the DSV model and identification of two new fungicides for disease management. Evaluation of new treatments for sweet cherry diseases - brown rot, gray mold, and powdery mildew. Characterization of QoI fungicide resistance in scab populations on almond and pear. Studies on the mode of action of phenylpyroles and anilinopyrimidines in Penicillium digitatum.