Eco-friendly management of root-knot nematodes in lettuce using biological and cultural practices: fallow, removal of infested roots, garlic-based cropping systems, and Bacillus subtilis BV09

Abstract Root-knot nematodes (RKN, Meloidogyne spp.) are plant-parasitic nematodes economically important for several horticultural crops. RKN management is difficult and expensive, requiring approaches that consider ecosystem balance to maintain RKN population below damaging levels. Garlic cultivation and Bacillus subtilis BV09 (BsBV09) application effects on the integrated management of Meloidogyne incognita in lettuce crops were evaluated. The experiment was conducted in RKN-infested field with the following treatments: Lettuce monoculture (control), garlic monoculture, lettuce intercropped with garlic, each with or without BsBV09 application. Fallow soil and removal of infested roots were also performed. After performing the management practices, only lettuce monoculture was grown in all plots, maintaining BsBV09 in the respective treatments. RKN population was evaluated before implementation and at each harvest. Lettuce and garlic yield, income, and agroeconomic indices were evaluated. Garlic cultivation and BsBV09 reduced RKN population; root removal reduced the RKN population by ~ 80%. Fallow also reduced RKN but caused prolonged unproductivity. Production per garlic plant was improved by intercropping and BsBV09. Production per lettuce plant on its third cropping cycle was affected by the intercropping when garlic plants were large. Nevertheless, growing lettuce and garlic concurrently achieved advantageous results in the agroeconomic indices. M. incognita attack activated plants’ biochemical defense response. BsBV09 and intercropping system helped to protect lettuce and garlic plants against the stress caused by M. incognita infection. Garlic cultivation and BsBV09 are efficient practices for integrated RKN management in lettuce crops, protecting plants against RKN infection and providing income even during RKN management.