Managing pod molds on snap beans
CALS Impact Statement
This research has focused on the least toxic and most sustainable methods for pod mold control on snap beans. In most cases, two fungi are involved in the pod mold complex, and are referred to by growers as gray mold and white mold. Both fungi have a wide host range, and can attack many species of crop plants, ornamentals and weeds. Both fungi are versatile with respect to temperature and moisture requirements needed to cause diseases. For these reasons, both fungi are very difficult for producers to control in any cropping system. The research conducted in this project aims to find ways to stop these fungi from attacking economically important crop plants.
The stakeholders most interested and most affected by this research are processing and fresh market snap bean producers. However, this research is also very relevant to dry bean producers. The most efficacious material used by the industry has been determined to have carcinogenic activity, and snap beans were removed from the EPA registration label of that product in fall of 2005. Our research has focused on alternatives to the use of this chemical, which will result in the use of least toxic inputs and high quality disease-free snap beans. Snap beans are grown in central and western regions of the state for fresh and processing markets. The 2003 crop was valued at $40.4 million. Fresh production accounted for 66 percent of the total and puts New York 4th across the nation. Processing sales of $13.4 million rank New York 3rd in the nation. Around 25,000 acres of dry beans are planted in New York State, for a value of around $10 million.
For the last 4 years, we have conducted extensive field and laboratory research on new fungicides and less toxic fungicides as replacements for vinclozolin for snap bean producers. Our search is for materials that provide effective simultaneous control of both white mold and gray mold, diseases that are caused by fungi with very broad host ranges and that are very aggressive and well-adapted for survival. A less toxic alternative for conventional producers is a product named Endura, known chemically as boscalid. This material has been approved recently (2005) by the EPA and the DEC for use in New York. The material is a carboximide that has shown properties that are environmently less toxic than vinclozolin. It is effective for gray mold control and shows promise for efficient white mold control when applied at critical management times. We have also explored the use of some organic products, but these have not been able to suppress pod molds when weather conditions are conducive for disease development (wet). The pod mold `tool box` contains the following materials, some of which are also being examined by EPA because of potential environmental problems, including Topsin M, Rovral, Bravo, Elevate, and Quadris. In 2006 we initiated a project to develop a decision tool for use by producers needing to control pod molds. Once completed, this tool will guide producers through a decision making process backed by research knowledge on efficacy of each suggested control strategy.
Because of our efforts, growers have comparative information on the efficacy of registered materials for disease control efforts in 2006. The pod mold "tool box" is still shy of individual materials that will provide control of both white and gray molds simultaneously, but combinations and timing have been identified that should be of use to commercial producers. Cultural practice management tools (non-chemical strategies) have also been outlined so that growers can minimize disease impact in years where weather is conducive for disease development. These include the maintenance of good air drainage by avoiding close proximity to hedgerows, avoiding narrow row spacing to facilitate good airflow and dry foliage, avoiding plant injuries that provide nutrients for ingress of fungi, and avoiding over-fertilization and frequent irrigation that keeps the canopy wet. The lack of weed control also provides additional sites for sporulation by producing a favorable microclimate for infection.
Rotating fields with grains and corn and incorporating debris immediately following harvest is beneficial because micro-organisms feed on the survival structures called sclerotia. Applying fungicides during flowering, and ensuring good coverage of blossoms are also beneficial measures. These combined efforts provide benefits useful to farmers (snap bean and dry bean) in conventional, transitional, and organic settings. In addition, less toxic material is released into the environment during the course of snap bean production.
funding source description
New York State Vegetable Growers Association
Pennsylvania Vegetable Growers Association
North East Integrated Pest Management Center - USDA