CONTROL OF ROOT KNOT NEMATODE IN LETTUCE AND WATERCRESS WITH PREDATORY FUNGI ISOLATED FROM THE SOIL OF THE CERRADO BAIANO

Abstract

Among the diseases affecting lettuce and watercress, those caused by root-knot nematodes (Meloidogyne spp.) are responsible for the poor vegetative development of these plants. Therefore, this study aimed to evaluate the effectiveness of two isolates of nematode-predatory fungi from the genus Arthrobotrys, obtained from Cerrado soil in Bahia, applied individually or in combination, in the control of root-knot nematodes in lettuce and watercress.The two fungal isolates were propagated on Petri dishes containing CMA medium and incubated at 25°C in a BOD-type growth chamber for 10 days. Inside a laminar flow chamber, the plates were opened and, using a cork borer, 150 fungal-colonized discs were obtained. These discs were then placed into a plastic bag containing approximately 1000 g of commercial vermiculite substrate and maintained at room temperature for 7 days. After this period, the substrate colonized by the nematode-predatory fungi was placed in seedling trays (tube-type cells), and lettuce and watercress were sown. Fifteen days after sowing, seedlings were transplanted into plastic bags containing a sterilized substrate composed of a mixture of soil, cattle manure, and sand in a 2:1:1 ratio.Fifteen days after transplanting, the substrates were inoculated with 3000 Meloidogyne incognita eggs by making two holes next to each seedling and applying the eggs with the aid of an automatic pipette. Thirty-five days after nematode inoculation, the number of galls and eggs in the root system of lettuce and watercress was evaluated, along with plant height and shoot dry weight. Both fungal isolates significantly reduced root-knot nematode parasitism in lettuce and watercress.