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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #311780
Title: Rhizopus oryzae associated with Melanagromyza splendida and stem disease of sunflowers (Helianthus annuus) in California

Author
item MATHEW, FEBINA - South Dakota State University
item Prasifka, Jarrad
item GAIMARI, STEPHEN - California Department Of Food And Agriculture
item SHI, LI - Inner Mongolian Agriculture University
item MARKEL, SAMUEL - North Dakota State University
item GULYA, THOMAS - Retired ARS Employee

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2014
Publication Date: 3/26/2015
Citation: Mathew, F.M., Prasifka, J.R., Gaimari, S.D., Shi, L., Markel, S.G., Gulya, T.J. 2015. Rhizopus oryzae associated with Melanagromyza splendida and stem disease of sunflowers (Helianthus annuus) in California. Plant Health Progress. 16(1):39-42. DOI:10.1094/PHP-RS-14-0042.

Interpretive Summary: In September 2012, a female parental line in a Yolo, CA in sunflower seed-production field began displaying external stem symptoms that could not be attributed to any known disease. Symptoms appeared to be associated with tunneling caused by an un-identified insect. Stems were collected and Rhizopus oryzae (causal agent of Rhizopus head rot) and a minute fly, Melanagromyza splendida, were identified as the causal agent and associated insect, respectively. Further, R. oryzae was isolated from unbroken pupal cases. All commercial hybrids evaluated in the greenhouse were susceptible to stem infection by R. oryzae isolates. Yield implications and geographic distribution of this novel stem disease are unknown. This is the first report of R. oryzae causing stem disease in sunflowers and as its association with M. splendid, but the wide distribution of the both the causal agent and associated insect suggest the same symptoms and disease could occur at other locations where sunflowers are grown in the United States.

Technical Abstract: In September 2012, a female parental line in a Yolo, CA in sunflower seed-production field began displaying external stem symptoms that could not be attributed to any known disease. Symptoms appeared to be associated with tunneling caused by an un-identified insect. Stems were collected and Rhizopus oryzae (causal agent of Rhizopus head rot) and a minute fly, Melanagromyza splendida, were identified as the causal agent and associated insect, respectively. Further, R. oryzae was isolated from unbroken pupal cases. All commercial hybrids evaluated in the greenhouse were susceptible to stem infection by R. oryzae isolates. Yield implications and geographic distribution of this novel stem disease are unknown. This is the first report of R. oryzae causing stem disease in sunflowers and as its association with M. splendida.