VIEW ARTICLE

Gossypium hirsutum subsp. mexicanum var. nervosum, Leningrad Strain—A Source of Resistance to Verticillium Wilt. Stephen Wilhelm, Professor, Department of Plant Pathology, University of California, Berkeley 94720; James E. Sagen(2), and Helga Tietz(3). (2)(3)Staff Research Associate, and Assistant Specialist, respectively, Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 64:931-939. Accepted for publication 27 December 1973. DOI: 10.1094/Phyto-64-931.

Reports by investigators in the USSR that Gossypium hirsutum L. subsp. mexicanum var. nervosum, a wild, deep-rooting, perennial, short-day, cold-tolerant, Mexican species, is resistant to Verticillium wilt have been confirmed by greenhouse studies and field experimentation in the San Joaquin Valley of California. In both vegetative and fruiting phases of growth, the resistance effected localization of Verticillium to xylem tissues of the lower stem and prevented dehiscence of infected leaves and other symptoms. Resistance was transferred to hybrids with Upland cottons. The F₁, though developing rather extensive systemic vascular and leaf infection, was rated resistant. Likewise, corroborating reports from the USSR, the F₂ segregated for resistance and susceptibility in a ratio of approximately 3:1, which suggests dominant monofactorial inheritance. The botanical status of the wild Mexican cotton is clarified.