Sustainable Integrated Management of Weeds - Diseases in Cabbage Cropping Systems

Sustainable Integrated Management of Weeds - Diseases in Cabbage Cropping Systems

Summary

Summary
The goal of this project is to identify crop rotation schemes that suppress weeds and disease development in subsequent cabbage crops, and to identify management practices that result in integrated simultaneous control of both pests. The rotation crops being grown in the study prior to planting cabbage are sweet corn, alfalfa, clover and rye. Weed control was generally better in 2000 than in 1999. Standing weed counts, weed seed counts, and pathogen populations will be analyzed over the winter months. The impact of this study will be determined in 2001, when cabbage will be planted into each of the cropping systems at the three locations.

Objectives
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.

Methods
This research is being conducted at three locations, two of which are commercial fields: Bellona (property of Mr. Paul Roe), Cortland (property of Mr. Don Reed), and Geneva (property of the NYS Agricultural Experiment Station). Each trial is approximately two acres. The treatments are arranged in a randomized complete block design with four replications. Each treatment plot is 30 by 70 feet and is surrounded by a drive alley of 15 or 25 feet. The crops in the 1999 and 2000 study were sweet corn, alfalfa, clover, and rye. These treatments are being used to control weeds and inhibit growth of pathogens that are problematic in cabbage fields. Cabbage will be planted in each replicate plot in 2001. Weed counts were taken in each replicate plot at all three locations. Soil samples (approximately one liter) were removed from each plot and weed seed and pathogen populations were assessed.

Results
Weed control was generally much better in 2000 than in 1999. The clover and alfalfa stands were able to out compete the weeds and beautiful stands were achieved. Weed control in the corn plots was excellent.

Cortland location: Weed counts were taken on June 5. The dominant weeds were ragweed, white cockle, chickweed, and bluegrass. These weeds were present in all treatments except the sweet corn treatment. Weed counts were taken again in the corn plots on July 25, and only a few ragweed plants were present. No cabbage pathogens were detected in the soil samples.

Geneva and Bellona locations: Weed counts were taken on July 21. The dominant weeds observed were amaranth, ragweed, nettle, and quackgrass. No cabbage pathogens were detected in the soil samples. Seed counts from soil samples show high populations of lambs quarter at the Geneva location and chickweed at the Bellona location.

Impacts and potential contributions
The impact of this study will be determined in 2001, when cabbage will be planted into each of the cropping systems at the three locations. Previous research has shown that some weeds such as velvetleaf and ragweed support populations of the cabbage pathogen Sclerotinia sclerotiorum, the cause of white mold in cabbage. These same weeds are also known hosts of the pathogen Botrytis cinerea that causes gray mold in cabbage. There are no fungicides registered on cabbage that will provide control of white and gray molds. Weeds that are not known hosts for cabbage pathogens promote disease development by holding moisture in the cabbage canopy, which all pathogens find conducive.

Conventional growers currently use a range of herbicides to try to control weeds in cabbage. Controlling the weeds in cabbage fields has been shown to provide some control of the pathogens in cabbage fields. This is why hand weeding has been adopted by some growers when market prices are favorable. The potential contribution will be a sustainable and effective method for providing simultaneous weed and pathogen control in cabbage.

Reported November 2000

Collaborators: