Crown Canker of Pigeon Pea (Cajanus cajan) Caused by a Sterile White Basidiomycete in Puerto Rico. Walter J. Kaiser, Research Plant Pathologist, USDA, ARS, Western Regional Plant Introduction Station, Washington State University, Pullman 99164-6402. Pedro L. Melendez, Richard M. Hannan, and Mildred Zapata. Professor, Crop Protection Department, University of Puerto Rico, Mayagüez 00708; Horticulturist, USDA, ARS, Western Regional Plant Introduction Station, Washington State University, Pullman; and Graduate Student, Crop Protection Department, University of Puerto Rico, Mayagüez. Plant Dis. 71:1006-1009. Accepted for publication 18 March 1987. 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, 1987. DOI: 10.1094/PD-71-1006.

A sterile white basidiomycete (SWB) was isolated from crown cankers on naturally infected pigeon pea (Cajanus cajan) plants in western Puerto Rico. Fungal mycelium resembled that of Sclerotium rolfsii but did not produce sclerotia in culture or on infected plant tissues. Hyphal cells of the SWB were binucleate, and clamp connections were present on the hyphae. At times, fleshy, bractlike structures reminiscent of fruiting bodies developed beneath the soil surface in cankers of inoculated plants. No basidia were observed on these fleshy structures. In greenhouse inoculation tests, the pathogen caused preemergence and postemergence damping-off of pigeon pea. Sunken, reddish brown lesions often developed in the crown area of older, inoculated plants. Wounding of pigeon pea hypocotyls increased the size of cankers but not the number of symptomatic or dead plants. Infection of pigeon pea seedlings was greater at 30 C than at 15–25 C. The SWB was pathogenic to food crops from 11 genera and four families of plants.