Harnessing the role of garlic and control strategies in a crop succession with soybean affecting Heterodera glycines dynamics

Garlic is a significant winter cash crop in Brazil, succeeded by soybeans during the summer, providing economic benefits and other advantages. Soybeans are primarily cultivated for their seeds, but they can also be harvested as a vegetable known as edamame. Since there are currently no studies regarding the soybean cyst nematode (SCN)–Heterodera glycines (Ichinohe) in garlic-soybean-garlic crop succession, this study aimed to explore its role in addition to control strategies that affect SCN dynamics. The trials occurred in a central-pivot irrigation area naturally infested with SCN race 5 in Campo Alegre de Goiás, GO, Brazil, in 2023 and 2024. Six treatments were employed: (1) Bacillus subtilis; (2) Abamectin; (3) Nitrogen + amino acids; (4) Fluopyram; (5) Purpureocillium lilacinum + Trichoderma harzianum + organo-mineral fertilizer; and (6) Control. Although garlic is not a host for SCN, this PPN could survive in the soil and multiply in volunteer glyphosate-resistant soybean plants or weeds, which help maintain its population. Still, turning over the soil for garlic planting and allowing a fallow period reduced the population. Fluopyram and P. lilacinum + T. harzianum + organo-mineral fertilizer, particularly Fluopyram, provided a decrease in the number of J2 and females as well as higher productivity for both crops. In this context, sustainable practices can help reduce nematode populations, and biological products may play a crucial role in integrated management systems within this tropical region.