Rapeseed rotation, compost and biocontrol amendments reduce soilborne diseases and increase tuber yield in organic and conventional potato production systems

Abstract

Aims Integrating multiple soil and disease manage- ment practices may improve crop productivity and disease control, but potential interactions and limita- tions need to be determined. Methods Three different potential disease-suppressive management practices, including a Brassica napus (rapeseed) green manure rotation crop, conifer-based compost amendment, and three biological control or- ganisms (Trichoderma virens, Bacillus subtilis, and Rhizoctonia solani hypovirulent isolate Rhs1A1) were evaluated alone and in combination at sites with both organic and conventional management histories for their effects on soilborne diseases and tuber yield. Results Rapeseed rotation reduced all observed soil- borne diseases (stem canker, black scurf, common scab, and silver scurf) by 10 to 52 % in at least one year at both sites. Compost amendment had variable effects on tuber diseases, but consistently increased yield (by 9 to 15 %) at both sites. Biocontrol effects on disease varied, though Rhs1A1 decreased black scurf at the conventional site and T. virens reduced multiple diseases at the organic site in at least one year. Combining rapeseed rotation with compost amend- ment both reduced disease and increased yield, where- as biocontrol additions produced only marginal addi- tive effects. Conclusions Use of these treatments alone, and in combination, can be effective at reducing disease and increasing yield under both conventional and organic production practices.