SCREENING TOMATO SEEDLINGS FOR MULTIPLE DISEASE RESISTANCE

Two procedures for screening tomato (Lycopersicon esculentum Mill.) seedlings for resistance to three pathogens were developed. In one scheme, seeds were sprayed with a spore suspension of Fusarium oxysporum f. sp. radicis-lycopersici Jarvis & Shoemaker (fusarium crown and root rot). Resistant seedlings were root-dipped 2.5 weeks later in a spore suspension of Verticillium dahliae Kleb. (verticillium wilt), and 1 week following the root dip, leaves were rubbed with tobacco mosaic virus. In the other scheme, 2-week-old seedlings were dipped in a spore suspension of F. oxysporum Schlecht f. sp. lycopersici (Sacc.) Snyd. & Hans. races 1 and 2 (fusarium wilt). Resistant seedlings were root-drenched 1.5 weeks later with a suspension of Meloidogyne incognita Kofoid & White (rootknot nematode), and 1 week following, the leaves were rubbed with tobacco mosaic virus. These procedures were effective for disease screening, and their use should reduce the time required for development of two multiple disease-resistant populations. Inbreds from each population could be crossed to produce hybrids resistant to five pathogens.