|Kirk, William - Michigan State University|
|Qu, Xinshun - Pennsylvania State University|
Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2013
Publication Date: 1/1/2014
Publication URL: http://handle.nal.usda.gov/10113/58948
Citation: Wanner, L.A., Kirk, W.W., Qu, X. 2014. Field efficacy of nonpathogenic Streptomyces species against potato common scab. Journal of Applied Microbiology. 116(1):123-133.
Interpretive Summary: Potatoes are the fourth most important staple food crop, and are grown worldwide. However, potatoes are affected by numerous pests and diseases, resulting in crop losses and increased production costs for controlling disease. A disease for which there is currently no adequate control is potato common scab (CS), which decreases potato quality and marketability because of the wart-like or pitted lesions on the potato skin. Non-disease causing mmicroorganisms that may reduce potato CS were applied to field grown plants and evaluated in two studies, one in Michigan and one in Pennsylvania. Both locations had a history of severe CS. Control of CS by 5 strains of these non-diseasing causing microorganisms was inconsistent. However, trends in the severity and effectiveness of CS in treated plants suggest that very specific micro-environments are required for optimal control of CS. Future studies are underway to characterize these micro-environments. Increased understanding of the community of soil microorganisms offers an environmentally friendly alternative to chemical fumigation for CS control, and has promise for effective suppression of soil-borne plant disease for potato growers.
Technical Abstract: Reports of potato fields suppressive to common scab (CS) and of association of non-pathogenic streptomycetes with CS resistance suggest that non-pathogenic strains have potential to control or modulate CS disease. Biocontrol potential of non-pathogenic Streptomyces was examined in field experiments in 2 locations (MI and PA) in 2009 (5 non-pathogenic Streptomyces isolates, 3 potato cultivars, and 3 replicates) and again in 2010 (3 isolates, 3 cultivars, 10 replicates) in replicated trials. Tubers were scored for CS incidence and the type and extent of CS lesions. Of effects considered, only potato cultivar was consistently significant for both CS incidence and CS severity. The effect on CS severity and incidence of 5 potential biocontrol strains and of interaction between biocontrol strain and potato variety could not be statistically distinguished in some datasets. In these experiments, the potato cultivar and biocontrol strain were standardized. We conclude that inconsistent control of CS by non-pathogenic Streptomyces isolates is attributable to environmental influences, most likely through effects on soil microbial flora.