Growing for the future: Collective action, land stewardship and soilborne pathogens in California strawberry production

Abstract

Outlook Growing for the future: Collective action, land stewardship and soilborne pathogens in California strawberry production Margaret Lloyd, UC Cooperative Extension Farm Advisor, Yolo, Solano and Sacramento counties Tom Gordon, Professor, Department of Plant Pathology, UC Davis Sustaining high strawberry yields will require an integrated approach that includes collaborative management of fields to limit the spread of soilborne pathogens. required, one that integrates advances in disease resistance through breeding with closer attention to the factors that influence the survival, activity and spread of pathogen populations in soil. Many of the latter, such as rotating crops and cleaning equipment, frequently involve multiple operators. As a result, there is a need to recognize that patho- gen-free soil is effectively a common-pool resource and that protecting it will require collective action. The end of methyl bromide Since the early 1950s, diseases caused by soilborne pathogens have been managed primarily through the use of preplant soil fumigation. Before that time, Verticillium wilt, caused by Verticillium dahliae, imposed a major limitation on strawberry production. Recognition of the fungicidal prop- erties of chloropicrin and the enhanced efficacy achieved by addition of methyl bromide lifted this http://calag.ucanr.edu • JULY–SEPTEMBER 2016 101 Jack Kelly Clark C alifornia accounts for more than 80% of U.S. strawberry production, a harvest worth $2.5 billion in 2014. Fertile soils and the prevail- ing climate on the Central Coast support per acre yields twice that of Florida, the second largest pro- ducer, and 10 times more than most other states. Yet California strawberry growers face sig- nificant challenges. Among the most important is the declining availability of suitable land. The potential for a given field to produce an acceptable yield depends not only on physical and chemical characteristics of the soil but also, critically, on the presence or absence of soil dwelling pathogens that can infect strawberry roots and cause diseases that limit fruit production. As described below, effec- tive control of soilborne pathogens of strawberries was once readily achieved by means that are no longer available to strawberry growers. It now seems likely that no single measure will suffice to meet the challenge of soilborne patho- gens. Rather, a multi-faceted approach will be