EFFECTS OF MELOIDOGYNE-ARENARIA INFECTION ON M-INCOGNITA-RESISTANCE IN TOBACCO

Roots of tobacco resistant to Meloidogyne incognita host races 1 and 3 were separated into two portions using three different split-root tec hniques. One portion of each plant root was inoculated with eggs of M. arenaria and the other root portion with M. incognita. Eggs of M. are naria and M. incognita were applied to separate root portions either s imultaneously or M. incognita inoculation was delayed. After 45 to 60 days in the greenhouse, root portions were rated for galling and egg m ass number. M. arenaria infection of one root portion did not systemic ally predispopse the other portion to M. incognita infection. Plants w ith intact root systems were maintained at 25, 28, 31, or 35 degrees C and inoculated simultaneously with eggs of both species. M. incognita -resistance failed at temperatures above 28 degrees C. M. arenaria inf ection did not alter the M. incognita-resistance phenotype at differen t temperatures.