Efeito de produtos biológicos sobre nematoides causadores da casca-preta-do-inhame

Abstract

One of the main diseases affecting yam crops (Dioscorea spp.) in Brazil is the dry rot caused by Scutellonema bradys, Pratylenchus brachyurus and P. coffeae nematodes. The use of biological control agents is a promising practice that has been tested in order to reduce losses by pathogens. The objective of this work was to evaluate the nematicidal activity of commercial biological products on yam dry rot nematodes in vitro and in vivo. Trichodermil® (Trichoderma harzianum) at a concentration of 1.5 and 2.0 L/200 L of water; Presence® (Bacillus spp.) at 100 and 150 g/100 L; Quartzo® (Bacillus spp.) at 130 and 200 g/200L; Bio Ax® (rhizobacteria and organic carbon) at 5 and 7L/100L; and the control (distilled water), were tested in in vitro assays on S. bradys or Pratylenchus sp. In experiments performed under greenhouse conditions, healthy seed tubers were planted in sterilized soil and thirty days later the soil was infested with a suspension of 1,000 specimens of a S. bradys and P. coffeae mixed population. Then, after 30 days the following products were applied to the soil: Presence® 150 g/100L; Trichodermil® 2 L/200L and Bio Ax® 7 L/100L, at 100 mL per pot. Three months after planting, the sprouting percentage of the seed tubers was evaluated and in the fifth month, the nematode population densities were determined. The sprouting of seed tubers was of 100% in all treatments. Presence® and Trichodermil® caused 89% and 61% mortality in S. bradys respectively, at the highest concentrations. In specimens of Pratylenchus sp., Bio Ax® exhibited 51% and 45% mortality at higher and lower concentrations, respectively. Under greenhouse conditions, Presence® and Bio Ax® were more effective in reducing nematode population densities, when compared to the control.