VIEW ARTICLE

Influence of Rhizoctonia solani on the Susceptibility of Cotton Plants to Verticillium albo-atrum and on Root Carbohydrates. Farid Y. Khoury, Plant Pathologist, Ministry of Agriculture, Aleppo, Syria, Tucson 85721; Stanley M. Alcorn, Professor, Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 63:352-358. Accepted for publication 18 September 1972. DOI: 10.1094/Phyto-63-352.

Newly emerged seedlings of Gossypium hirsutum ‘Deltapine Smooth Leaf’ (DSL) and G. barbadense ‘Pima S-2’ (PS-2) grown in the greenhouse were less susceptible to Verticillium albo-atrum than were older plants. Rhizoctonia solani significantly increased the susceptibility of both cultivars to V. albo-atrum; generally PS-2 was as susceptible as DSL. The degree to which Rhizoctonia affected susceptibility varied with plant age, soil temperature, inoculum concentration, and interval between inoculations with the two pathogens. Levels of potassium hydroxide-soluble carbohydrates were significantly higher in roots of DSL at the first-leaf stage and of PS-2 at the cotyledonary and first-leaf stages when these cultivars were exposed to R. solani.