VIEW ARTICLE

Ecology and Epidemiology

Interactions Between a Vesicular-Arbuscular Mycorrhizal Fungus and Root-Knot Nematode on Soybean. M. K. Kellam, Former graduate research assistant, Department of Plant Pathology, University of Florida, 32611, Present Address of senior author: Department of Plant Pathology, University of California, Riverside, 92502; N. C. Schenck, professor, Department of Plant Pathology, University of Florida, 32611, Present Address of senior author: Department of Plant Pathology, University of California, Riverside, 92502. Phytopathology 70:293-296. Accepted for publication 20 September 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-293.

In greenhouse tests, roots of cultivar Pickett soybean plants were inoculated with chlamydospores of Glomus macrocarpus and/or eggs of Meloidogyne incognita by using an aluminum foil funnel technique. Soybeans were inoculated with one organism 10 days prior to the second organism or with both organisms simultaneously either at or 10 days after planting. After 14 wk, plants which were infected with both organisms had significantly fewer galls per gram of root, greater root weights, and higher yields than did those infected with the nematode alone. Chlamydospore production and percentage of mycorrhizal roots were not significantly different in the presence or absence of nematodes. Atypical hyphae, vesicles, and arbuscules of the fungus were observed in galled tissue and 57% of the galls examined were not associated with mycorrhizal roots. With the level of nematode inoculum used in these tests, the presence of G. macrocarpus reduced the number of galls produced by M. incognita; the presence of the nematode affected mycorrhizal development in the immediate area of the gall, but had little effect on the mean percentage of mycorrhizal roots or the number of chlamydospores produced by the fungus.