Implementation of an integrated peach rusty spot disease management program in commercial orchards

View the project final report

Commodities

• Fruits: peaches, general tree fruits

Practices

• Education and Training: demonstration, extension, on-farm/ranch research, participatory research
• Pest Management: biological control, biorational pesticides, chemical control

Rusty spot of peach is found throughout the United States and is a serious disease on susceptible cultivars. The pathogen causes a necrosis of epidermal cells, thereby reducing fruit quality. In New Jersey, a crop loss of $204/A was estimated by the IPM Program in 1997. Disease control is dependent on application of fungicides beginning at shuck-split, resulting in 6 to 8 sprays/season. However, research conducted at Rutgers (1999-2001) showed that optimum timing is from petal fall through second cover, a total of four sprays. Subsequent research (2000-2001) indicated that the bacterium Bacillus subtilis and the biorational potassium bicarbonate exhibited partial efficacy. Further work (2002-2004) showed that integration of either biofungicide with the standard significantly reduced conventional fungicide usage without any loss in disease control or yield. Given the above results, this project’s major objective is to implement at the commercial level the newly discovered reduced-risk strategies for rusty spot management. The overall goal will be to reduce usage of conventional fungicide by at least 50% while maintaining acceptable control. This goal will be achieved by a combination of optimized application timing and incorporation of biofungicides into the disease management program. Grower cooperators will apply a variety of integrated application schedules using both B. subtilis and potassium bicarbonate. Results from this study will validate use of these strategies at a commercial level. Ultimately, adoption of this approach by all stone fruit growers will improve grower profitability, reduce pesticide usage on fruit (improve food safety), decrease pesticide sprayed into the environment, and lessen applicator exposure.

Integrated strategy. In performing this project, our overall goal is to demonstrate to growers that highly efficient and effective disease management of peach rusty spot is possible through a combination of optimized application timing and judicious use of biofungicides. Relative to current management practices, successful implementation of the integrated program will result in a reduction of 50 to 75% of the conventional fungicide without any loss in disease control. This program results in less fungicide applied to edible fruit (improved food safety), less fungicide applied to the environment, and an improved profitability for commercial growers. Furthermore, since fewer applications are required and less toxic biofungicides are employed, the risk of applicator exposure is also reduced.

This proposal is a continuation of the last six years of experimentation on the epidemiology and management of rusty spot of peach. As such, it represents the implementation phase for the strategies that have been developed. Grower cooperators will apply several integrated disease management programs to portions of peach blocks known to have a history of rusty spot. Rutgers research and extension personnel will monitor the epidemics in each of these treatments to provide data for statistical comparison. These results, along with cooperator testimonials, will be used in extension presentations to enhance and stimulate further adoption by all growers.