Effect of Glomus intraradices on infection by Fusarium oxysporum f.sp. radicis-lycopersici in tomatoes over a 12-week period

Abstract

The interaction between Glomus intraradices Schenck & Smith, a vesicular–arbuscular mycorrhizal fungus, and Fusarium oxysporum Schlecht f.sp. radicis-lycopersici Jarvis & Shoemaker and its effect on tomato plants were investigated over a 12-week period. The root colonization by Glomus was not affected by the presence of Fusarium. The number of Fusarium propagules was consistently lower when the plants were inoculated with Glomus. The presence of Glomus decreased root necrosis caused by Fusarium in weeks 5, 11, and 12, but no significant effect was observed for the other 9 weeks. The results obtained at any observation time for the endomycorrhizal colonization and the Fusarium population, but not for the percent of root necrosis evaluation, were consistent throughout the 12-week experiment. It is concluded that the parameters used to study the interaction between a vesicular–arbuscular mycorrhizal fungus, a fungal root pathogen, and a host plant must be measured at different times after inoculation with the pathogen to make sure that observations are representative of the interaction under study.