Soil incorporation of buckwheat as a pre-plant amendment provides control of Rhizoctonia damping-off and root rot of radish and Pythium damping-off and root rot of cucumber

Buckwheat is a rapidly growing cover crop with the potential to improve soil quality and health. In this study, the impact of buckwheat plant material (BPM) as a soil amendment on seedling emergence and suppression of damping-off and root rot of radish (Rhizoctonia solani) and cucumber (Pythium ultimum) was investigated in pot assays. Fresh BPM grown in a greenhouse potting mix for 4 weeks was chopped in small 1-2 cm long pieces and incorporated into field soil containing 0-10% of R. solani or P. ultimum inoculum produced on sterilized rye seed. The infested soil was then incubated for 0-8 weeks prior to planting radish or cucumber seed. The effects of BPM on plant growth and disease development were determined 2 weeks after planting. There was no disease protection if radish and cucumber seeds were planted within 1-2 weeks after soil incorporation of BPM. Disease protection was evident when planting was delayed for 3 weeks after BPM amendment to soil. BPM soil amendment provided protection of radish plants from Rhizoctonia damping-off and protection of cucumber plants from Pythium damping-off and root rot. BPM amendments had no effect on promoting plant growth but slightly increased soil pH. In amended soil receiving 4% and 10% of BPM planted with radish or cucumber seeds 0, 3 and 8 weeks later, total populations of indigenous fungi were 0.66-2.01 log units higher and bacteria were 0.53-0.92 log units higher compared with the populations in the non-amended soils. Buckwheat soil amendment offers a potential option to improve plant and soil health.