THE INFESTATION OF TOMATO SEED BY FUSARIUM-OXYSPORUM F SP RADICIS-LYCOPERSICI

The infestation of seed by Fusarium oxysporum f.sp. radicis-lycopersic i occurred at rates of O.1 to 0.01% in fruit on stem-infected plants. Direct infection of fruit in the flower or young developing fruit stag e resulted in a greyish-brown lesion on the stylar end of the fruit or mummification. F. oxysporum f.sp. radicis-lycopersici was isolated fr om all seeds in such fruit. Picked fruit inoculated on the stem scar a lso became infected but 96 h after inoculation of the fruit, the seed was not infested or infected. The contact of clean seed with hands tha t had previously handled F. oxysporum f.sp. radicis-lycoperisici-infes ted sawdust resulted in a high level of seed infestation. The fungus s urvived on seed sent across Canada and stored for up to 12 weeks. Trea tment with NaOCl or 0.1 N HCl did not completely disinfest infested se ed.