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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Compost and Biocontrol Amendments on Stem Canker, Black Scurf, and Common Scab of Potato, 2006

Authors
item Larkin, Robert
item Manmathan, Harish - UNIVERSITY OF MAINE
item Tavantzis, Stellos - UNIVERSITY OF MAINE

Submitted to: Plant Disease Management Reports
Publication Type: Research Notes
Publication Acceptance Date: February 27, 2007
Publication Date: April 15, 2007
Citation: Larkin, R.P., Manmathan, H., Tavantzis, S. 2007. Effects of Compost and Biocontrol Amendments on Stem Canker, Black Scurf, and Common Scab of Potato, 2006. Plant Disease Management Reports. vol 1: p. v065.

Interpretive Summary: Soilborne diseases are persistent problems in potato production and sustainable management options are needed. Stem canker, black scurf, and common scab are three of the most common soilborne diseases of potato. The use of composts and biological amendments to actively alter or manipulate soil microbial communities and result in natural disease-suppressive soils is a promising management approach. In this research, two composts and two biological amendments were assessed alone and in various combinations for their effects on common soilborne diseases of potato and tuber yield. All treatments reduced stem canker, and a bacterial biocontrol agent, fungal biocontrol agent, and conifer compost, as well as their combinations, also reduced black scurf, relative to the nontreated control. The bacterial and fungal biocontrol agents, but not compost, also reduced common scab. Conifer compost increased total yield, and all compost treatments increased marketable yield. This research indicates that biological amendments can be useful for reducing soilborne diseases, compost can significantly improve yield, and the combination of the right compost and biological amendments can simultaneously reduce disease and improve yield. These results have important implications for future development of sustainable disease management.

Technical Abstract: Two composts and two biological control agents were evaluated alone and in combination for their effects on the development of soilborne diseases of potato. The experiment was conducted on field research plots in Newport, ME. The compost amendments consisted of commercially available compost blends, with one being a conifer-based compost made from hemlock bark, and the other being a hardwood-based compost made from aspen. Biocontrol treatments consisted of the bacterial biocontrol agent Bacillus subtilis GB03, and a hypovirulent strain of R. solani, HV-Rs. All treatments significantly reduced stem canker relative to the nontreated control, by 27 to 50%. The bacterial agent B.subtilis, hypovirulent Rs strain, conifer compost, and their combinations, all reduced the incidence of black scurf, and B.subtilis, HV-Rs, Bsub plus HV-Rs, and conifer compost plus HV-Rs also significantly reduced the severity of black scurf, by 23 to 48% relative to the nontreated control. Common scab was present as both the russet and erumpent-type lesions, and total scab was reduced by B.subtilis and HV-Rs treatments. Scab was increased by the hardwood compost treatment, due primarily to an increase in erumpent-type scab lesions. Total tuber weight was significantly greater with the conifer compost treatment, and marketable weight was greater for all compost treatments and combinations, averaging 30 to 54% greater than the nontreated control. These results indicate that B.subtilis, HV-Rs, and conifer compost can reduce soilborne diseases of potato, and that combinations of these treatments can reduce disease and improve yield.

Last Modified: 8/22/2014
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