Pasteuria thornei, a novel biological seed treatment for Pratylenchus brachyurus control in soybean

The goal of this study was to evaluate the efficiency of Pasteuria thornei as a biological seed treatment for Pratylenchus brachyurus control in soybean (Glycine max). Seeds of soybean 'SYN1080' were treated with three concentrations of P. thornei endospores per seed (5 x 10(6), 107, 1.5 x 10(7)), together with two other treatments for comparison: a commercial control containing abamectin (0.58 mg seed(-1)) and a mixed treatment containing abamectin (0.58 mg seed(-1)) and 1(0)7 endospores of P. thornei. These seeds were sown in plastic cups containing soil inoculated with 1000 nematodes (Trial 1) and 600 nematodes (Trial 2). The trials were evaluated at 60 and 90 days after inoculation (dai). The total of nematodes extracted from the roots of each plant was used as the assessment criterion. Only the highest concentration of P. thornei endospores (1.5 x 10(7)) consistently reduced the final populations of P. brachyurus by 25-50% compared to the non-treated seeds. The treatments containing abamectin were superior in reducing the nematode population in all trials and evaluations. There was no visible synergistic effect of the combined use of abamectin and P. thornei in the same treatment at 90 dai.