Disease Note

Diseases of Cultivated Sunflower in Hawaii. T. J. Gulya, USDA-ARS, Department of Plant Pathology, North Dakota State University, Fargo 58105. J. J. Ooka, Department of Plant Pathology, University of Hawaii, Kapaa 96746; and M. K. Mancl, Northrup King Co., Woodland, CA 95695. Plant Dis. 69:542. Accepted for publication 7 March 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-542e.

Sunflower (Helianthus annuus L.) has been grown in winter nurseries in Hawaii by breeders from the mainland United States since 1970. During 1980 and 1984, diseases were identified in these nurseries on the basis of field symptoms and laboratory confirmation of pure cultures. Alternaria leaf and stem spot (A. helianthi (Hansf.) Tub. & Nish.) and Phoma black stem (P. macdonaldii Boerma) were the major diseases observed. Charcoal rot (Macrophomina phaseolini (Tassi) Goid.), midstalk rot (Sclerotinia sclerotiorum (Lib.) de Bary), bacterial stalk rot (Erwinia carotovora (Jones) Dye), and Septoria leaf spot (S. helianthi Ell. & Kell.) occurred sporadically. Notably absent were downy mildew (Plasmopara halstedii (Farl.) Berl. & de Toni), rust (Puccinia helianthi Schw.), and Phomopsis stem canker (P. helianthi Munt.-Cvet.). No diseases of sunflower were found in Hawaii that do not also occur in the continental United States.