Localised and Systemic Effects of Root-Knot Nematode On Incidence and Severity of Fusarium Wilt in Cotton

Abstract

Cotton seedlings were grown with a divided root system and inoculated with root-knot nematode (Meloidogyne incognita) and Fusarium oxysporum f. sp. vasinfectum on the same or opposite halves of the root system. Wilt incidence was increased by the nematode, but only in plants where both organisms were together on the same part of the root system. However, in a second experiment in which plants growing in Meloidogyne infested soil were stem inoculated with the wilt pathogen, the nematode caused an increase in wilt severity, despite the physical separation of the two organisms. These results are discussed in terms of a localised effect of the nematode on initial infection and a systemic effect on subsequent disease development.