Abstract
At various times during the growing season, Meloidogyne egg masses were collected from the roots of either grape or kiwifruit, or from tomato plants grown in association with these two crops. Between 23% and 87% of the eggs were found to be parasitized by fungi. Paecilomyces lilacinus and Verticillium chlamydosporium were the only species consistently isolated from these parasitized eggs. The fungicides mancozeb and iprodione, when used in combination at 150 mg/l, markedly suppressed radial growth of both P. lilacinus and V. chlamydosporium on agar but had no effect on hatch of Meloidogyne eggs or motility of second-stage juveniles. They were therefore used to estimate the degree of natural suppression of root-knot nematodes occurring in grape vineyards and kiwifruit orchards. When applied to field soil in pots, the fungicides reduced population densities of both P. lilacinus and V. chlamydosporium and significantly reduced the percentage of eggs parasitized. However, this did not result in a significant increase in the number of root-knot nematode juveniles in the soil. This suggested that the egg-parasitic fungi had little impact on root-knot nematode populations and that the fungi were mainly eliminating nematodes in excess of the carrying capacity of the root system.
Published Version
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