First Report of Diaporthe stewartii Causing Phomopsis Stem Canker of Sunflower (Helianthus annuus) in Minnesota
Phomopsis stem canker is one of the most economically important sunflower diseases in the northern Great Plains (Mathew et al. 2015). In October 2015, lesions consistent with Phomopsis stem canker were observed on sunflower (Helianthus annuus L.) in a commercial field in Polk County, MN (47°46′12″ N, 96°24′00″ W). Five plants displaying elongated, brown stem lesions were obtained. Stems were cut into small pieces (10 mm), surface-sterilized, and plated onto potato dextrose agar (PDA). The plates were incubated for 10 days at 22°C under 12 h of alternating light/dark conditions. Two isolates of brown colonies were hyphal-tipped and transferred to fresh PDA plates.
DOI of Published Version
Olson, T. R.; Krontz, B.; Markell, S. G.; Gulya, T. J.; and Mathew, F. M., "First Report of Diaporthe stewartii Causing Phomopsis Stem Canker of Sunflower (Helianthus annuus) in Minnesota" (2017). Agronomy, Horticulture and Plant Science Faculty Publications. 279.