|Larkin, Robert - Bob|
Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2008
Publication Date: 7/15/2008
Citation: Larkin, R.P., Tavantzis, S., Bernard, E., Alyokhin, A., Erich, S., Gross, S. 2008. Compost and Biological Amendment Effects on Soilborne Disease and Soil Microbial Communities. American Phytopathological Society. 98:586.
Technical Abstract: Effects of compost and biological amendments on soilborne diseases and microorganisms were assessed in field trials in northern Maine under both conventional and organic potato production practices. Three different biocontrol amendments, hypovirulent Rhizoctonia solani Rhs 1A1 (HvRs), Bacillus subtilis (Bsub), and Trichoderma virens (Tvir), as well as a nontreated control were used in conjunction with plots both amended and not amended with a conifer-based (Hemlock bark) compost (19 Mg/ha). At the conventional site, compost amendment reduced incidence and severity of black scurf by 12-27%, and increased tuber yields by 13-23%. Biocontrol treatments (Tvir and HvRs) reduced incidence and severity of black scurf by 9-31% but had no significant effect on yield. The combined effect of compost and biocontrol amendments reduced black scurf by 30-48% and increased yield. At the organic site, where soil was already rich in organic matter, compost did not significantly reduce scurf or scab, but increased tuber yield (9-30%). Biocontrol treatments (Tvir and Bsub) reduced incidence and severity of black scurf by 10-48%, scab by 5-20%, and the total of all diseases by 15-30%. All treatments significantly affected soil microbial communities, with compost amendments generally resulting in more pronounced changes in community characteristics than biological amendments. Overall disease levels were lower and yields higher at the organic site. Appropriate compost and biological amendments had significant positive effects on soil quality, disease reduction, and yield, and should play an important role in sustainable soil and disease management programs.