Root lesion nematodes limit the productivity of several crops of economic importance, requiring alternatives for their management. Resistance inducers activate enzymes involved in defense mechanisms and micronutrients can influence this process by acting as enzymatic cofactors. Thus, the objective of this study was to evaluate the effect of foliar application of a commercial organomineral fertilizer and its association or not with zinc (Zn) and manganese (Mn) micronutrients on the Pratylenchus brachyurus suppression and soybean plant development under greenhouse conditions. Shoots of soybean were treated 10 days after germination and inoculated with 5000 nematodes/plant five days after the treatments, using untreated plants as controls. Treatments consisted of a commercial product based on phosphorylated mannanoligosaccharide derived from the cell wall of Saccharomyces cerevisiae (here coded as MOS), Zn, Mn, MOS+Zn, MOS+Mn or MOS+Zn+Mn. At sixty days after establishment of treatments, the plants were collected and evaluated for vegetative analysis, nematological analysis and nutrient contents. The work was repeated at different times: experiment 1 from November 2016 to January 2017 and experiment 2 from October to November 2017. All treatments were efficient in controlling P. brachyurus in at least one of the evaluated nematological parameters, compared to the control. However, only the plant spraying with MOS+Zn results in significative reduction of the total number of nematodes and the number of P. brachyurus nematodes per gram of soybean root in both experiments. In addition, spraying of plants with Mn increased shoot dry weight and all treatments resulted in higher concentrations of copper, Zn and Mn in soybeans leaves compared to control.

Elicitors of plant resistance are compounds that activate enzymatic processes involved in plant defense. Micronutrients also play an important role in plant responses against pathogens because they function as enzyme cofactors. Despite their well-known benefits, elicitors and micronutrients have been little investigated in nematode control. This study aimed to assess the effects of Agro-Mos® (a commercial biostimulant) and micronutrients (Zn and Mn), alone and combined, on soybean inoculated with Meloidogyne javanica. Seeds of soybean were sown in trays, treated 15 days after germination, and inoculated with 2000 eggs and juveniles of M. javanica at the time of transplanting. Treatments were as follows: 1 L/ha Agro-Mos®, 2 L/ha Metalosate® Zinc, 1.5 L/ha Metalosate® Manganese, Agro-Mos® + Zn, Agro-Mos® + Mn, and Agro-Mos® + Zn + Mn. Untreated inoculated and uninoculated plants were used as controls. At 60 days after inoculation, plants were harvested and evaluated for vegetative growth, nutrient content, and nematode parameters. All treatments were effective in reducing M. javanica population density in roots compared to the control. Agro-Mos®, Agro-Mos® + Zn, and Agro-Mos® + Zn + Mn were the most effective, reducing total nematode number and population density by 55–78% (P ≤ 0.05) in relation to the control. Agro-Mos® + Zn increased shoot dry weight. The results show that balanced fertilization can be used as part of an integrated nematode control strategy.