VIEW ARTICLE

Ecology and Epidemiology

Transmission of Macrophomina phaseolina in Sunflower by Cylindrocopturus adspersus. S. M. Yang, Research Plant Pathologist, USDA Conservation and Production Research Laboratory, Agricultural Research Service, P.O. Drawer 10, Bushland, TX 79012; C. E. Rogers(2), and N. D. Luciani(3). (2)Research Entomologist, USDA Conservation and Production Research Laboratory, Agricultural Research Service, P.O. Drawer 10, Bushland, TX 79012; (3)Agronomist, Compania Continental, Parana-(E.R.), Argentina. Phytopathology 73:1467-1469. Accepted for publication 18 May 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1983. DOI: 10.1094/Phyto-73-1467.

Seventeen of 123 adult Cylindrocopturus adspersus (sunflower stem weevil) collected from the internodes and roots of overwintered sunflower (Helianthus annuus) plants, and four of 133 adult C. adspersus collected from growing sunflower plants in the field yielded Macrophomina phaseolina, the causal agent of charcoal rot, on PDA-SP medium. Seven of 168 adults carried sclerotia of M. phaseolina. This pathogen was isolated on PDA-SP medium from three oviposition sites of C. adspersus on two of 38 field-grown sunflower plants, but was not isolated from subterranean parts of the infected plants. Three of 45 sunflower plants fed on by adult C. adspersus showed brown external discoloration of stems and black sclerotia in the pith, typical symptoms of infection by M. phaseolina. Control plants did not exhibit symptoms of infection. These results indicate that a small percentage of adult C. adspersus carry M. phaseolina externally and transmit the pathogen to sunflower during oviposition via that sealed egg cavity in the stalk.