Biofumigation: Opportunities and Challenges for Control of Soilborne Diseases in Nursery Production

Abstract

Soilborne diseases reduce crop performance, increase costs to the nursery producers, and can cause potential ecological damage to the natural environment. In particular, soilborne diseases caused by Phytophthora nicotianae and Rhizoctonia solani are the most economically important problems of southeastern U.S. nursery producers. Methyl bromide was widely used as a standard treatment in many parts of the world until the implementation of the Montreal Protocol. Since then, many chemical and nonchemical soilborne disease management methods have been tested but are not yet providing effective and consistent results like methyl bromide. Cover crops that belong to the Brassicaceae family can be incorporated into the soil to control soilborne diseases, and this process is widely known as biofumigation. Glucosinolates that are available inside Brassicaceae plant cells can be hydrolyzed into isothiocyanates, and these compounds are proven to be highly biocidal to many microorganisms (including fungi, oomycetes, nematodes, and bacteria), insects, and germinating weed seeds. The use of biofumigant cover crops is a newer area of research in woody ornamental nursery production that has been previously explored most extensively in row crop, vegetable, fruit, and flower production. This review article compiles previous research observations in biofumigation while emphasizing the potential of biofumigation to control diseases in nursery production caused by soilborne pathogens.