Authors
S. T.
Koike
,
University of California Cooperative Extension, Salinas 93901
; and
K. V.
Subbarao
,
Department of Plant Pathology, University of California, Davis, and U.S. Agricultural Research Station, Salinas 93905
Endive (Cichorium endivia) and escarole (broad-leaf type of C. endivia) are two of the many leafy vegetables produced commercially in coastal California. For several years, both crops have been affected by a disease that causes soft, watery, brown leaf decay. In the tightly appressed heads of endive and escarole plants, decay generally spreads in a concentric circle, resulting in circular whorls of brown, rotted leaves within diseased heads. Such symptoms make the heads unmarketable. In the Salinas Valley (Monterey County), the disease was much more prevalent during 1998, when weather was affected by “El Niño.” Rhizoctonia solani was isolated consistently from symptomatic leaves of both endive and escarole. Pathogenicity was tested by placing two agar plugs of representative isolates inside the leaf whorls of 15 potted plants each of endive (cv. Tres Fine Maraicchere) and escarole (cv. Full Heart). Watery, brown leaf decay, similar to symptoms observed in the field, occurred on all plants within 7 days after inoculation, and R. solani was reisolated. Control plants, treated with sterile agar plugs, did not develop disease. Tests were repeated, and results were similar. Anastomosis-group testing revealed that four endive isolates belonged to AG2-2 (1). This appears to be the first report of leaf blight of endive and escarole caused by R. solani in California.
Reference: (1) Sneh et al. 1991. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN.
