IMPROVING SUSTAINABILITY, EFFICIENCY, AND EFFICACY OF PEACH DISEASE MANAGEMENT STRATEGIES: BIOFUNGICIDES, CONVENTIONAL FUNGICIDES, AND ABIOTIC ENVIRONMENTAL FACTORS

JUSTIFICATION Introduction. Major diseases on peach and nectarine include brown rot blossom blight and fruit rot, scab, and bacterial spot. Each of these diseases, if not effectively controlled, alone can cause 100% crop loss when pathogen inoculum levels and environmental conditions are favorable for disease development. Other diseases, such as rusty spot and constriction canker can also contribute to significant yield loss if not managed properly. Unfortunately, disease-resistant cultivars are not commercially available for most peach and nectarine diseases. Even when resistant cultivars exist, such as for bacterial spot, rusty spot, and constriction canker, they are not available for all harvest periods, provide only partial resistance, do not have favorable horticultural characteristics, or are less marketable. Similarly, cultural disease control tactics are at best partially effective. Given the above, commercial peach growers are heavily dependent on the application of fungicides and bactericides for effective disease management. The cost of implementing such programs can be quite high. Furthermore, since most applications are timed according to tree phenology or on a calendar basis, many unnecessary sprays may be applied. Improving Strategies. The current fungicide-intensive approach to controlling peach diseases can be improved by (i) incorporating effective biofungicides; (ii) more efficiently utilizing current and new conventional fungicides; and (iii) timing applications according to biological/environmental requirements for disease development. All three approaches have the potential for reducing total amount of conventional fungicide usage. Furthermore, successful implementation of these approaches can result in more effective disease control, thereby increasing overall peach production and contributing to the long-term sustainability of farming operations. EXPECTED IMPACT Incorporation of effective biorational fungicides will allow growers to reduce their overall reliance on conventional fungicides. Furthermore, most biofungicides have lower overall toxicities than conventional products, resulting in reduced pesticide exposure for grower applicators, farm workers, and the environment. Many conventional fungicides can control pathogen growth and/or reproduction at different phases in the disease cycle. However, many novel fungicides of current or new chemistries are often released and used in standard disease control programs without consideration for these specific capabilities. Thus, a thorough understanding of a fungicides capabilities is needed to more effectively and efficiently utilize it in a disease control program. Fungicide application timing according to tree phenology and/or the calendar can result in (i) poorly timed sprays, and therefore disease outbreaks, when inoculum and weather conditions are favorable for disease development or (ii) overuse of fungicide when conditions are less favorable for disease development. Application of fungicides or bactericides according to biological / environmental requirements will allow growers to optimize their pesticide usage.