Synergistic interactions between Rhizoctonia solani Kuhn, Verticillium dahliae Kleb., Meloidogyne spp. and Pratylenchus neglectus (Rensch) Chitwood & Oteifa, in potato

Samples of a sandy soil and a marine clay soil sterilized by steam were put in 55-l containers insulated with polystyrene and placed outdoors on a brick pavement. Sandy soil was infested singly or in all possible combinations with root-knot nematodes (Meloidogyne spp.) and the fungi Rhizoctonia solani and Verticillium dahliae, and the marine clay soil was infested with the root-lesion nematode Pratylenchus neglectus and the same fungi to evaluate the effects of these organisms on the yield of potato. The experiments were carried out from 1983 to 1986. Tuber yield was reduced by single infestations of the Meloidogyne spp. and V. dahliae but not significantly by R. solani or R neglectus. A three-factor interaction: nematode x R. solani x V. dahliae was found in both experiments. R. solani and V. dahliae showed significant synergistic effects when soil was infested with the Meloidogyne spp. or P. neglectus.