Sustainable Integrated Management of Weeds - Diseases in Cabbage Cropping Systems

Sustainable Integrated Management of Weeds - Diseases in Cabbage Cropping Systems

Summary

The objectives were to identify crop rotation schemes that suppress weeds and disease development in subsequent cabbage crops, and to identify management practices that result in integrated control of both pests. At three trial locations, the rotation crops grown prior to planting cabbage were sweet corn, alfalfa, clover and rye. Suppression of winter annuals and short-lived perennials was greatest in the sweet corn and rye rotations. Weed control was poorest in the alfalfa rotations. Hot dry weather suppressed disease. A new pathogen, Fusarium species, was found at all three locations, and caused significant head rot on mature cabbage plants

Objectives/Performance Targets

Identify crop rotation schemes that suppress weeds and disease development in subsequent cabbage crops.
Identify sustainable weed and disease management practices that result in integrated control of both pests

Accomplishments/Milestones

The cabbage variety “Genesee” was planted at all three trial locations in 2001: Geneva Experiment Station, June 1; Roe Acres, June 14; Reed’s, June 6. Weather conditions were hot and dry throughout the growing season. Total monthly rainfall (in.) was 5.10, 1.98, 2.35, 4.11, and 1.83 for Jun, Jul, Aug, Sep, and Oct, respectively. The only site where irrigation was possible was at the Experiment Station, where a total of 3.2 inches of water was applied. The transplants were commercially produced, and delivered with other shipments to Roe Acres. Symptoms of black rot were evident on the transplants at the time of planting at Roe Acres (the last field to be planted). However, the hot dry weather inhibited further disease development.

In general, the rotation effect on weed control was consistent throughout all three sites. Field observations in 1999 and 2000 indicated substantially fewer weeds were present in the sweet corn plots than in the other rotation treatments. This is due in part to timely herbicide applications and to planting a rye cover crop after harvest. Suppression of winter annuals and short-lived perennials, such as shepherds purse and campion, was greatest in the sweet corn and rye plots. Extremely high populations of these weeds were found at the Reed site in the clover and alfalfa rotations. These two rotation treatments did not receive herbicide applications at any of the three sites. Weed control was poorest in the alfalfa plots, followed by the clover plots. Rye plantings seemed to control most weed species. Statistical analysis has yet to be conducted to see whether these field observations are significant.

Disease pressure at all three locations was very low due to hot dry weather. Insignificant levels of white and gray molds, caused by Sclerotinia sclerotiorum and Botrytis cinerea, were observed. A new disease that has been observed at low levels in cabbage fields in previous years was the dominant disease in all 3 locations. The pathogen has been tentatively identified as a Fusarium species. Infections result in small circular lesions that develop into a large rotted area on the cabbage head. In mass, the fungal mycelium appears pink to orange in color. Incidence of this disease was highest at the Reed location. Statistical analysis will be conducted to determine the influence of treatment on incidence of disease.

Impacts and Contributions/Outcomes

The potential contribution of this research is the development of sustainable simultaneous weed and disease control in cabbage. The outcome is complicated by the presence of a new pathogen in the system, and the lack of traditional pathogens due to unfavorable environmental conditions

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