On-Farm Use of a Hybrid Vetch Cover Crop to Reduce Fusarium Wilt in Seedless Watermelon

On-Farm Use of a Hybrid Vetch Cover Crop to Reduce Fusarium Wilt in Seedless Watermelon

Summary

Watermelon growers in the South and other regions of the U. S. need sustainable controls for Fusarium wilt that fit their production practices and are effective against all races of the pathogen. We will compare winter cover crops of ‘Cahaba White’ hybrid vetch with rye and fallow soil (the negative controls) and with methyl bromide plus vetch (positive control) for suppression of Fusarium wilt. The project will be done on Coosaw Farms, Fairfax, SC, in a naturally infested field.

Objectives/Performance Targets

1. Determine the level of Fusarium wilt in treatments;

   Determine the level of the Fusarium fungus in soil collected from treated plots;

   Measure the yield (number) of marketable-sized fruit;

   Calculate the cost and economic return of each treatment;

   Communicate results to stakeholders

Accomplishments/Milestones

On Aug. 23, 2007, the coordinator, his two technicians, the Clemson University Extension horticulturist, the cooperating grower, and his daughter met in the office of Coosaw Farms to discus the details of the project. A fallow control, which is the grower’s standard field procedure, was added to the experimental design.

On October 23, 2007, the grower gave us one hour notice that vetch and rye would be seeded. Plots were located in a no-till field that had been cropped to field corn in spring 2007. There was a significant amount of corn debris left in the field that interfered with vetch emergence. Stand counts of vetch on November 13 were 67 plants/square meter and 72 plants/square meter on December 4, 2007. This stand was 50% and 30% of the stand achieved at the research station in tilled soil in 2006 and 2007.

Soil samples were collected on December 4, 2007 and cultured to determine the background level of Fusarium oxysporum in the plots before treatments were applied. There were no differences among the four treatments at this point. The average level of Fusarium oxysporum in the plots was 760 colony-forming units per gram of soil.

In 2008, vetch biomass will be measured before incorporation. The grower will transplant seedless watermelon in late March. Plots will be checked monthly for symptoms of Fusarium wilt. Marketable-sized fruit will be counted before commercial harvest.

Impacts and Contributions/Outcomes

This project will determine if cover crops of ‘Cahaba White’ hybrid vetch can be used as a sustainable control against Fusarium wilt of watermelon. The cover crop could replace use of methyl bromide or other broad-spectrum soil fumigants. A field day will be co-hosted by the O’Neals and the project director in June or July 2007. Data collected from the project will be presented in handouts. Information from this project will be published in both research and Extension outlets. Three presentations will be given to educate growers and researchers about the results of this project.

Collaborators: