Biological products for the control of Pratylenchus brachyurus in maize crops

This study aimed to evaluate the effect of seed treatment with biological nematicides on the control of Pratylenchus brachyurus population in maize and crop yield. For this, a greenhouse experiment and a field experiment on clay soil were conducted in Juranda, Paraná State, Brazil. 

In both experiments, seeds of the maize hybrid K9310 VIP3 were subjected to the following treatments: untreated control, abamectin (Avicta^® 500 FS), Bacillus subtilis + B. methylotrophicus (Rizos^® + Onix^®), B. amyloliquefaciens + Trichoderma harzianum (NemaControl^® + StimuControl^®), and Pochonia chlamydosporia (Rizotec^®). In a greenhouse, seeds were sown in pots containing 950 cm3 of autoclaved substrate. 

Five days after emergence, each seedling was inoculated with 500 individuals of P. brachyurus. After 75 days, the plants were evaluated for nematode and vegetative variables. Prior to the field experiment, samples of soil and the crop preceding maize were collected for an initial characterization of nematode populations in the area. At 60 days after sowing, plants were evaluated for nematode reproduction. Crop yield was assessed at 150 days after sowing. 

All biological treatments reduced P. brachyurus in maize roots under greenhouse conditions, with the combination of B. amyloliquefaciens and T. harzianum providing the best results. Additionally, nematode variables were negatively correlated with plant height. Under field conditions, there was a negative correlation between P. brachyurus and crop yield, and biological treatments led to a mean increase of 6 bags ha−1 in maize yield compared with the control.

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