|DUNG, JEREMIAH - Oregon State University|
|WALENTA, DARRIN - Oregon State University|
|HAMM, PHILLIP - Oregon State University|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2015
Publication Date: 4/14/2015
Citation: Dung, J., Alderman, S.C., Walenta, D., Hamm, P. 2015. Spatial patterns of ergot and quantification of sclerotia in perennial ryegrass seed fields. Plant Disease. doi: 10.1094/PDIS-08-14-0787-RE.
Interpretive Summary: Ergot is a major disease of perennial ryegrass grown for seed in the Columbia Basin, Oregon. Quantitative data concerning the severity and spatial distribution of ergot in commercial perennial ryegrass seed productions fields were collected in 2012 and 2013. This is the first study to quantify spatial patterns of ergot in perennial ryegrass and provides insights into possible mechanisms that contribute to ergot etiology and epidemiology
Technical Abstract: Ergot, caused by Claviceps purpurea, is a major disease of perennial ryegrass grass grown for seed in eastern Oregon. The objective of this research was to quantify and describe the spatial patterns of ergot severity in each of three 50 ha commercial fields of perennial ryegrass grown for seed in 2012 and 2013. A total of 1,433 and 1,405 quadrats were sampled among the three fields in 2012 and 2013, respectively, and the percentage of quadrats with ergot ranged from 59 to 90%. The mean incidence of infected seed heads in each quadrat ranged between 13 and 29%, while mean severity in each quadrat ranged from 0.2 to 0.5 sclerotia per seed head. Significant autocorrelation and clustering were observed in all three fields in both years as indicated by Moran’s I and SADIE indices of aggregation. The mean number of ergot sclerotia collected from each field after harvest ranged from 4 and 15 sclerotia m-2 in 2012 and between 18 and 119 sclerotia m-2 in 2013. Sclerotia left in perennial fields after harvest are a significant source of inoculum that should be targeted for control. This is the first study to quantify spatial patterns of ergot in perennial ryegrass and provides insights into possible mechanisms that contribute to ergot etiology and epidemiology.