January 7, 2020 – Soil solarization is an organic method that has been shown to control weeds, pathogens, and nematodes in areas with hot summer temperatures. Biosolarization, a relatively new technique, combines the use of soil solarization and organic soil amendments to enhance the results of solarization. While biosolarization has proven effective in a number of studies, its efficacy varies across study regions, cropping systems, and pathogen communities. In 2018, OFRF provided a grant to Dr. Ashraf Tubeileh at California Polytechnic State University, San Luis Obispo to study the effect of biosolarization and cover crops on weeds and soil-borne pathogens.

Results from this research demonstrated that solarization effectively reduced weed biomass; it also reduced Verticillium dahliae (a fungal plant pathogen) populations by 80.7%, reduced crop mortality by 54.9%, and roughly tripled yields compared to non-solarized fields. Cover cropped plots tended to perform better than non-cover cropped plots, with cover crop mulch providing the best weed control and healthiest strawberries.

The study concluded that there is potential for success using biosolarization in organic strawberry production on the central coast of California, although this method may provide better results with crops that have growing seasons that are less than three months.

A detailed account of the project is available to read here.

Dr. Tubeileh’s work is also featured in OFRF’s free online training program for organic specialty crop farmers in California. This open educational resource is a joint effort between OFRF, the University of California Sustainable Agriculture Research and Education Program (UC SAREP), and California Polytechnic State University in San Luis Obispo, with funding from the U.S. Department of Agriculture’s (USDA) Agricultural Marketing Service through grant AM170100XXXXG011.

Designed especially for beginning farmers and farmers transitioning to organic production, this self-paced program combines descriptive essays, video lectures from university faculty, and virtual field trips to demonstrate organic principles and practices.

View/take the first learning module on Organic Soil Health Management.