Effects of crop rotation and biocontrol amendments on Rhizoctonia disease of potato and soil microbial communities

Authors: Larkin, Robert - Bob; BREWER, MARIN - University Of Georgia

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2020
Publication Date: 4/14/2020
Citation: Larkin, R.P., Brewer, M.T. 2020. Effects of crop rotation and biocontrol amendments on Rhizoctonia disease of potato and soil microbial communities. Agriculture. 10:128. https://doi.org/10.3390/agriculture10040128.
DOI: https://doi.org/10.3390/agriculture10040128

Interpretive Summary: Stem canker and black scurf diseases, both caused by the fungus Rhizoctonia solani, are persistent problems for potato production in the Northeast. Current control methods are not adequate and integrated sustainable approaches are needed. The use of more effective crop rotations and biological control organisms are approaches that provide some control separately but may be more effective when used together. In this research, rotation crops and biocontrol amendments were evaluated for suppression of Rhizoctonia disease of potato and their interactive effects on soil microbial communities. In greenhouse trials, ryegrass rotations were most effective in reducing stem canker, and increased populations of R.zeae, which may be involved in biocontrol of R.solani. In field trials evaluating selected biocontrol treatments in combination with different rotations, a barley/ryegrass rotation resulted in lower disease and higher potato yields at one location, and the combination of barley/ryegrass rotation with biocontrol organisms provided the greatest disease reduction. Soil microbial community characteristics differed among the rotation crops and biocontrol treatments. Significant biocontrol by crop interactions were observed, demonstrating the complex interactions among rotation crops, biocontrol treatments, and soil microbial communities, and indicating that biocontrol can be enhanced within beneficial rotations. This research demonstrated the usefulness of combining biological control with compatible crop rotations as well as the importance of soil microbial communities and their interactions for improved disease control. This research is useful for scientists, crop advisors, and growers, providing practical information on improving disease control in potato production.

Technical Abstract: Rotation crops and biocontrol amendments were investigated for suppression of Rhizoctonia solani on potato (Solanum tuberosum) and their interactive effects on soil microbial communities. Greenhouse trials were conducted to evaluate selected rotation crops, including barley, common and “Lemtal” ryegrass, clover, potato, and combinations of barley with ryegrass or clover, for their effects on populations of R. solani and Rhizoctonia disease. Potato and clover preceding potato resulted in higher disease severity than most other rotations, whereas ryegrass reduced stem canker severity. In addition, all ryegrass treatments resulted in substantially higher populations of R. zeae. Field trials evaluating selected biocontrol treatments in combination with different rotations were conducted at two locations in Maine. Potatoes were treated with the biocontrol organisms Laetisaria arvalis, Trichoderma virens, or Bacillus subtilis and planted following rotation crops of barley and ryegrass, barley and clover, or potato. The barley/ryegrass rotation significantly reduced incidence and severity of stem canker and increased tuber yield at one location. Efficacy of the biocontrol treatments varied by rotation and location, with L. arvalis and T. virens reducing black scurf in some rotations and increasing some aspects of tuber yield at one location. Soil microbial community characteristics differed among rotation crops and biocontrol treatments. Significant crop by biocontrol interactions were observed demonstrating the complex interactions among rotation crops, biocontrol treatments, and soil microbial communities, and indicating that biocontrol can be enhanced within beneficial rotations.