VIEW ARTICLE

Effect of Concentration of Inoculum and Method of Inoculation on Development of Verticillium Wilt of Sunflowers. P. E. Moser, Postdoctoral Fellow, Department of Plant Pathology, Macdonald College of McGill University, Ste. Anne de Bellevue, Quebec, Canada, Current address of senior author: Idaho Falls, Idaho; W. E. Sackston, Professor, Department of Plant Pathology, Macdonald College of McGill University, Ste. Anne de Bellevue, Quebec, Canada, Current address of junior author, National Research Center for Oil Crops, I.N.I.A., Apartado 240, Cordoba, Spain. Phytopathology 63:1521-1523. Accepted for publication 12 June 1973. DOI: 10.1094/Phyto-63-1521.

Hypodermic inoculation of sunflowers (Helianthus annuus) with Verticillium dahliae gave more uniform and predictable infection than root dip inoculation. There was a direct linear relationship between concentration of inoculum and the speed of development of leaf symptoms and degree of stunting of the susceptible inbred line CM 162. Stunting was not observed in the resistant line CM 144; leaf symptoms were less severe, developed more slowly, and at the lower inoculum concentrations affected fewer plants than in CM 162. Infection occurred in some susceptible plants inoculated hypodermically with a suspension averaging one spore per plant. Consistently uniform infections were obtained with an average of 10 spores per plant.