Effect of cropping pattern and green manure on the antagonistic potential and the diversity of egg pathogenic fungi in fields with Heterodera schachtii infection

Field populations sometimes are a mixture of species and genotypes, Awhich makes them unsuitable for resistance screening against root-knot nematodes. To solve this problem, a special protocol Awas developed to produce species-specitic populations originating Irom single iuveniles and to prevent contamination of inoculum of Aspecies-specitic populations by other aggressive Mdoido^ymʹ species. These populations are representative of the type races Aoccurring in the Netherlands. Before multiplication of the egg mass. the Meloidogyne female was identified by isozyme patterns ofesterase A(Est) and malate dehydrogenase (Mdh). The Petri dish method was evaluated lo study the infection process of M.chaplu. M. chitwoodi. Aand M.ftillux on potato roots. High infection levels were obtained following inoculation with a water suspension of juveniles. The Apotential use of the Peli-i dish method for screening for resistance was assessed by inoculation of.juveniles of Glohodem species on roots Aof susceptible and resistant potato cultivars. resulting in clear differential ractions. During this study, a deviating group of held Apopulations was distinguished based on isozyme band patterns. It was later described us a new species. M. fallax.