VIEW ARTICLE

Mycorrhizae in Plant Disease Research

Effect of Soil Fumigants and Fungicides on Vesicular-Arbuscular Fungi. John A. Menge, Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 72:1125-1132. Accepted for publication 15 January 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1125.

Mycorrhizal fungi are cosmopolitan, beneficial fungi that are associated with the roots of most crops. Mycorrhizal fungi have been shown to consistently stimulate plant absorption of P, Zn, and Cu, but they also can enhance uptake of K, Ca, Fe, Mg, Mn, and S (15,23,37). Due to improved mineral nutrition, plants normally grow more rapidly and appear healthier than non mycorrhizal plants, especially an soils of low fertility (4-9, IS, 18, 23-25,37.47,53,55,61,62). The use of fungicides and fumigants to control soilborne pathogens is commonplace. Recently, concern has developed among agriculturists about the effects of pesticide usage upon beneficial mycorrhizal fungi. Are the benefits of fungicides and fumigants (Increased crop growth via destruction of pathogenic organisms) being diluted because they also destroy mycorrhizal fungi and thereby reduce nutrient uptake by crops? A substantial amount of accurate although fragmented data is now available on the interaction between mycorrhizal fungi and fungicides and fumigants. The purpose of this review is to summarize this information, synthesize it into generalizations, and identify areas in need of further research. Excellent reviews on the application, efficiency, mode of action, and chemistry of both fumigants (14,40,59) and fungicides (14,26,60) are available. These aspects will be discussed only as they apply to vesicular-arbuscular (VA) mycorrhiza1 fungi. Pesticide nomenclature is that used by Thompson (59,60).