Leaf constituents of Curcuma spp. suppress Meloidogyne hapla and increase bacterial-feeding nematodes.

Bioactive compounds extracted from agronomical plants have the potential to be ecologically safe and efficient alternatives to restricted broad-spectrum nematicides for managing root pests like Meloidogyne hapla. This study determined the effects of Curcuma longa and C. mangga leaf extracts and constituents on M. hapla infection, beneficial nematodes found in soil, and plant growth under glasshouse conditions over 350-420 degree-days (base 10°C). Incorporation of 60 and 120 g fresh leaves (kg soil)-1 of both Curcuma spp. suppressed the numbers of M. hapla infecting roots of tomato cv. Rutgers but increased beneficial nematodes in soil with minimal negative effect on plant health and growth. Curcuma mangga appears to be more favourable to beneficial nematodes than C. longa. Rhabditis, Acrobeloides and Eucephalobus were the dominant beneficial nematodes isolated from soils amended with Curcuma spp. The safe and selective activities of Curcuma spp. suggest potential for developing biologically integrated M. hapla management strategies. [ABSTRACT FROM AUTHOR]