Skip to main content
ARS Home » Southeast Area » Raleigh, North Carolina » Plant Science Research » Research » Publications at this Location » Publication #339257
Title: Three pythium species isolated from severely stunted wheat during an outbreak in North Carolina

Author
item LOOKABAUGH, EMMA - North Carolina State University
item SHEW, BARBARA - North Carolina State University
item Cowger, Christina

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2017
Publication Date: 8/8/2017
Citation: Lookabaugh, E., Shew, B., Cowger, C. 2017. Three pythium species isolated from severely stunted wheat during an outbreak in North Carolina. Plant Health Progress. 18:169-173.

Interpretive Summary: Large portions of eastern North Carolina experienced prolonged soil waterlogging in 2016. Severely stunted wheat plants from saturated fields were examined and the micro-organism Pythium was usually associated with the symptoms observed. Three species of Pythium were identified from between two and five counties each: P. irregulare, P. spinosum, and P. vanterpoolii. P. vanterpoolii and P. spinosum have not previously been reported as pathogens in U.S. wheat. All three species caused root rot when re-inoculated on wheat plants. These Pythium species cause disease, rather than living simply on debris in the soil, and are thus likely to have contributed to the extreme stunting and yield loss observed in North Carolina wheat in 2016. The 15 isolates were tested for sensitivity to the pesticide mefenoxam, and all were found to be sensitive. Prolonged periods of low soil oxygen likely predisposed North Carolina wheat to unusual levels of Pythium root rot in 2016.

Technical Abstract: Large portions of eastern North Carolina experienced prolonged soil waterlogging in 2016. Severely stunted wheat plants from saturated fields were examined and Pythium consistently was associated with the symptoms observed. Three species of Pythium were identified among 15 isolates derived from wheat roots and crowns: P. irregulare, P. spinosum, and P. vanterpoolii. Each species was isolated from samples that came from between two and five counties. P. vanterpoolii and P. spinosum have not previously been reported as pathogens in U.S. wheat. All three species caused root rot when re-inoculated on wheat plants. These species are not opportunistic or mainly saprophytic on other hosts; therefore, it is likely that they contributed to the extreme stunting and yield loss observed in North Carolina wheat in 2016. The 15 isolates were tested for sensitivity to mefenoxam at 100ug/ml a.i. and none was insensitive. Prolonged hypoxia likely predisposed North Carolina wheat to unusual levels of Pythium root rot in 2016.