First Report of Leptosphaeria lindquistii (Sexual Stage of Phoma macdonaldii) on Sunflower in North Dakota and Minnesota. P. A. Donald, Department of Plant Pathology, North Dakota State University, Fargo 58105. W. M. Bugbee (USDA-ARS), and J. R. Venette, Department of Plant Pathology, North Dakota State University, Fargo 58105. Plant Dis. 70:352. Accepted for publication 5 December 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-352e.
Overwintered sunflower stalks (Helianthus annuus L.) with symptoms of Phoma black stem were collected during the spring of 1985 in Minnesota and North Dakota. Stalk sections with perithecia were placed in a sterile moist chamber for 1 wk. Perithecia containing mature asci with ascospores were examined, and fungal structures fit the description of Leptosphaeria lindquistii Frezzi, the sexual stage of Phoma macdonaldii Boerema. Single asci were aseptically transferred to potato-dextrose agar, and colonies of P. macdonaldii with pycnidia developed within 7 days. Sunflower seedlings spray-inoculated with 1.5 × 106 conidia per milliliter, incubated 48 hr in a moist chamber, then kept in the greenhouse for 5 days developed stem and leaf lesions. This is the first report of L. lindquistii in North America.