Criteria for Quantal Host Response of Tomato Plants to Infection by Verticillium dahliae. S. Visser, Plant Pathologist, Horticultural Research Institute, Private Bag X293, Pretoria 0001, Republic of South Africa. M. J. Hattingh, Associate Professor, Department of Plant Pathology, University of Stellenbosch, Stellenbosch 7600, Republic of South Africa. Plant Dis. 64:207-208. Accepted for publication 19 September 1979. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-207.

Symptoms of Verticillium wilt of tomato were compared as criteria of quantal host response to infection by Verticillium dahliae. Vascular discoloration was a reliable criterion but required the destruction of the host. Wilting was the most reliable criterion that could be repeatedly evaluated on the same plant.