Potential of aqueous extracts of basidiomycetes to control root-knot nematodes on lettuce

ABSTRACT The root-knot nematode (Meloidogyne incognita) is one of the main pests of lettuce due to the crop’s high susceptibility, unavailability of registered nematicides and lack of resistant cultivars. The aim of this study was to evaluate the potential of aqueous extracts of ten basidiomycete fungi for root-knot nematode control (in vitro and in vivo) on lettuce. The aqueous extracts of these fungi were initially evaluated in vitro in relation to their nematostatic and nematicidal activity. All extracts inhibited the hatching of second-stage juveniles of nematodes. The extracts that provided the highest mortality index (Pleurotus ostreatus, P. citrinopileatus, P. pulmonarius and Boletus sp.) were applied in pots containing autoclaved and infested soil with root-knot nematode. After 24 h, one lettuce seedling (cv. Regina) per pot was transplanted using soil treated with distilled water as control. After 50 days, we observed that soil treated with fungal extracts reduced, approximately, 70% of nematode reproduction. Plants treated with extracts obtained higher fresh mass and extracts of Boletus sp. and P. pulmonarius reduced damages to roots, being considered as potential bio-controllers of this nematode.