Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2000
Publication Date: N/A
Interpretive Summary: Fungicides are applied to tomatoes for control of foliar diseases over several weeks during fruit development resulting in potential hazards to farm workers and consumers. This research was conducted to investigate preliminary observations that a hairy vetch cover crop can reduce foliar diseases of tomatoes. A three-year field experiment was conducted at Beltsville, MD to determine the impact of various mulching practices and fungicide schedules. Hairy vetch cover crop mulch was shown to suppress foliar diseases of tomato from 52 to 88% compared to tomatoes grown on bare soil and from 16 to 54% compared to tomatoes grown with black polyethylene mulch. The reduction of soil splash dispersal by rain drops in mulched soil was the factor most consistently associated with disease reduction. Reduced susceptibility of tomato foliage and reduction in the length of the leaf wetness period also may have contributed to reduced tomato disease when grown in hairy vetch in selected years. This research will be useful to researchers, extension personnel, and tomato growers looking for ways to reduce fungicide requirements and increase food safety.
Technical Abstract: The use of mulch or compost to reduce foliar diseases of fresh market tomato may reduce current levels of fungicide input. Between 1997 and 1999, foliar diseases were monitored in tomatoes grown in beds of bare soil, bare soil covered with black polyethylene, bare soil amended with composted dairy manure, and hairy vetch. Disease severity was lower in tomatoes grown in vetch versus other bed strategies in 1997 and versus bare soil or compost in 1998 and 1999. Disease severity was lower in tomatoes grown in polyethylene versus bare soil in 1998 and 1999 and versus compost in 1999. Following rainfall in 1998 and 1999, soil coverage of tomato leaflets and the rain-driven dispersal of soil particles were significantly lower in plots with polyethylene and vetch versus bare soil or compost. The susceptibility of detached tomato leaflets to Alternaria solani was significantly lower in vetch plots versus other bed strategies in 1997. In 1998 sensor wetness duration was lower in plots with polyethylene and vetch versus bare soil or compost. The reduction of splash dispersal in mulched soil was the factor most consistently associated with disease reduction, although susceptibility and wetness duration reductions may have contributed in selected years.