Reduction of nematode damage by root colonization with arbuscular mycorrhiza (Glomus spp.) in tomato-Meloidogyne incognita (Tylenchida: Meloidogynidae) and carrot-Pratylenchus penetrans (Tylenchida: Pratylenchidae) pathosystems.

Abstract

Pot studies on the effects of mycorrhizal root colonization on plant growth and nematode reproduction in tomato-Meloidogyne incognita and carrot-Pratylenchus penetrans pathosystems were carried out. The mycorrhizal fungus Glomus mosseae did not protect tomato plants inoculated with the pathogen M. incognita when it was inoculated simultaneously with the mycorrhiza, as plants inoculated with M. incognita died before harvest. On the other hand, when tomato seedlings were inoculated with the nematode three weeks after mycorrhization, colonization of tomato roots by G. mosseae compensated for the reduction of plant growth caused by M. incognita infection. Tomato shoot weight was 24% greater and gall index 33% lower than plants inoculated with the nematode alone, and final soil densities of M. incognita were reduced by 85% when tomato roots were colonized by the mycorrhiza. Root infection by P. penetrans reduced carrot growth, but soil inoculation with Glomus sp. spores compensated for the damage caused by P. penetrans. Addition of Glomus spores to soil reduced P. penetrans soil densities by 49%.