Field Studies of Plant Growth-Promoting Rhizobacteria for Biological Control of Rotylenchulus Reniformis on Soybean

Rotylenchulus reniformis (Linford & Oliveira), the reniform nematode, is the primary economic pathogen in cotton production and also causes significant economic losses on soybean production individually or collectively alongside soybean cyst and root-knot nematode in the southern region of the United States. Two Plant-Growth Promoting Rhizobacteria (PGPR) strains previously found with the ability of managing soybean cyst and root-knot nematode were evaluated for their biocontrol potential on reniform nematode in the soybean field at Tennessee Valley Research and Extension Center (TVREC) in Belle Mina, AL. The soil is a Decatur silt loam soil (24% sand, 49% silt, and 28% clay) and naturally infested with reniform nematode. In furrow sprays were applied on the seeds at planting time with the rate of 1×10⁷ CFU/seed. Clothianidin plus B. firmus I-1582 and Abamectin seed were treated before planting. Plots consisted of 2 rows, 7 m long with 0.9 m row spacing and were arranged in a randomized complete block design with five replications. Blocks were separated by a 6 m wide alley. All plots were maintained throughout the season with standard herbicide, insecticide, and fertility production practices as recommended by the Alabama Cooperative Extension System. Results indicated all the plant growth parameters were similar among the treatments at 45 DAP. Strain Bmo3 (Bacillus mojavensis) significantly reduced reniform eggs per gram of root at 45 DAP compared to the untreated control, which had an equivalent level of reniform population density as the chemical standard Abamectin (P ≤ 0.10). Yield was similar among all the treatments. However, Abamectin supported the highest yield followed by strain Bve2 (B. velezensis).