Integration of Bacillus-Rhizobium inoculants and tillage to manage dry bean and soybean root rot

Field studies were conducted in north central Minnesota to integrate management strategies to limit the effects of root rot and soil physical factors that affect dry bean and soybean yields. Disruption by moldboard tillage of the soil impedance layer (>2,000 Kpa at 15 cm soil depth) reduced disease severity (DS; 1 = no disease 9 = dead plant) from 4.4 to 3.8 (chisel vs. moldboard tillage) in dry bean. In soybean DS was reduced by 12%. Inoculation of dry bean with Bacillus subtilis MBI600 plus Rhizobium tropici UMR 1899 reduced DS from 4.7 to 3.5 (uninoculated vs. inoculated). In soybeans inoculation with Bradyrhizobium japonicum RCR 3437 plus B. subtilis MBI600 decreased DS from 3.9 to 3.1 (uninoculated vs. inoculated). In dry bean plots population of Fusarium solani differed between chisel and moldboard at 0-7 cm depth, but not at 7-15 cm depth. In soybean plots no differences were found. Dry bean yields in moldboard were 21% greater than in chisel tilled plots (869 vs. 1,050 Kg ha super(-1) respectively). Dry bean yields were unaffected by inoculation. Soybean yields were increased by 105% with inoculation (1,569 vs. 3,221 Kg ha super(-1)) and by 10% when moldboard was compared to chisel tilled plots (2,509 vs. 2,282 Kg ha super(-1)). Integration of tillage and inoculation may be beneficial in the control of bean and soybean root rot.