Efficacy of crop succession and bionematicide application for controlling <i>Pratylenchus brachyurus</i> in soybean

Integrated management is essential for keeping nematode populations below the economic damage thresholds. This greenhouse study evaluated the effects of applying commercially available bionematicides to a range of cover crop species on the infestation by <i>Pratylenchus brachyurus</i> of successively planted soybean roots. Initially, soybeans were inoculated with 500 specimens of <i>Pratylenchus brachyurus</i> and cultivated for 85 days. Afterward, greenhouse pots were planted with brachiaria (<i>Urochloa ruziziensis</i>), crotalaria (<i>Crotalaria spectabilis</i>), pearl millet ADR 300 (<i>Pennisetum glaucum</i>), or maize (<i>Zea mays</i>), with or without bionematicide treatments. The bionematicides used were <i>Bacillus licheniformis</i> + <i>B. subtilis</i> + <i>Purpureocillium lilacinum</i> (Trials 1 and 2) and <i>P. lilacinum</i> + <i>Trichoderma harzianum</i> (Trials 3 and 4). In Trial 1, crotalaria reduced nematode reproduction by 97% without bionematicide treatment, achieving 90% control when combined with bionematicides. In Trial 2, bionematicides applied to cover crops + soybean reduced nematode populations by 42%, with crotalaria achieving 94% control. Trials 3 and 4 confirmed that cover crops, particularly crotalaria, reduced nematode populations compared to maize. The combination of <i>P. lilacinum</i> + <i>T. harzianum</i> and crotalaria was the most effective, achieving up to 97% control. Overall, bionematicide agents were most effective when applied to both cover crops and soybean, reducing nematode densities by over 80%. These findings underscore the efficiency of integrating crotalaria with bionematicides as a sustainable strategy for managing <i>P. brachyurus</i> in soybean production systems.