Necrotic spot of melon, a new virus disease

Abstract

Muskmelon necrotic spot, new to Japan, is characterized by 3 types of leaf symptom: necrotic specks, large necrotic spots, and veinal necrosis. Necrotic streaks are produced on stems and petioles. The virus induced primary local lesions and systemic necrotic spots on muskmelon, cantaloupe, and Cucumis melo var. makuwa and local lesions only on watermelon, cucumber, and C. melo var. conomon. No other cucurbits tested were infected. About 20% seed transmission occurred. The virus survived heating to 60C. for 10 min., 9-10 days storage in vitro, or 1: 50, 000 dilution. Purified preparations contained spherical particles 31 m/μ/ diam. Some similarities appear to exist between this virus and Freitag's wild cucumber [Echinocystis lobata] mosaic virus [cf. 36: 299].