Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2005
Publication Date: N/A
Interpretive Summary: The nematode Anguina and the bacterium Rathayibacter can cause seed loss in orchardgrass or prevent exports when detected in seed, although the extent of seed loss in fields is unknown. Five commercial orchardgrass seed production fields were examined to determine yield loss from the Anguina and Rathayibacter. Among the 5 fields examined, up to 24% seed heads had Anguina, although seed loss was less than 0.2%, while Rathayibacter occurrence in up to 27% seed heads, with corresponding seed loss of up to 7.3%.
Technical Abstract: Anguina sp. is a floral infesting nematode of orchardgrass which forms galls that replace the seed. Anguina sp. is also a vector of the bacterial pathogen Rathayibacter rathayi, which causes galls or gummosis in orchardgrass panicles. The percentage of orchardgrass panicles infected or percentage seed loss from Anguina or Rathayibacter in five commercial orchardgrass seed production fields in Oregon during 2003 and 2004 was determined. The percentage of panicles with Anguina ranged from 9 to 24%, although the percentage of seed replaced by Anguina was less than 0.2 %. The number of galls per panicle ranged from 1 to 29. However, more than 50% of panicles contained only a single Anguina gall and few panicles had 8 or more galls. The percentage of panicles with Rathayibacter ranged from 3 to 27%. Percentage seed loss from Rathayibacter ranged from 0.1 to 7.3%. Seed loss in orchardgrass seed production fields assessed for both Anguina and Rathayibacter was found to be as great as 8%. The number of Anguina galls remaining in fields following harvest ranged from 0 to 10 per 0.25 m2.