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Disease Note. First Report of Race 2 of Verticillium dahliae on Tomatoes in South Africa. J. F. Ferreira, V.O.P.R.I, Private Bag X 293, Pretoria 0001, Republic of South Africa. P.C. van der Merwe, and S. P. Naude. V.O.P.R.I, Private Bag X 293, Pretoria 0001, Republic of South Africa. Plant Dis. 74:530. Accepted for publication 26 October 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0530E. Within a commercial planting of tomatoes (Lycopersicon esculentum
Mill.) at Malelane, eastern Transvaal, plants of the cultivars Flora-Dade
and Contessa showed wilting, yellowing of leaves, and vascular
discoloration normally associated with Verticillium wilt caused by V.
dahliae Kleb. Flora-Dade is resistant to race 1 of V. dahliae (1).
Isolation from the discolored vascular bundles of the stem, 3 cm above
soil level, yielded typical microsclerotial colonies of V. dahliae. For
pathogenicity tests, microconidial suspensions (3.0 X 106 conidia/ml-1)
were used to inoculate seedlings of differentials in their second true
leaf stage by dipping their roots in the inoculum (2). Susceptible
cultivars Red Kaki and Heinz 1370, lacking the Ve gene, wilted.
However, resistant Flora-Dade, with the Ve gene, also wilted. On
the basis of these findings and the reisolation of the pathogen, this
South African isolate was designated V. dahliae race 2. |