The bacterial biocontrol agent pasteuria penetrans can help control root-knot nematode on sugarcane

Abstract

ROOT-KNOT NEMATODE (Meloidogyne javanica) is one of the most damaging pests of sugarcane, often causing heavy losses in coarse-textured sandy soils. The bacterial parasite Pasteuria penetrans is a potentially useful biocontrol agent and in a 2015–16 survey it was found at relatively high levels in three of the 126 sugarcane fields surveyed. Soil was collected from one of the heavily-infested fields and a pot experiment established to compare root-knot nematode multiplication in naturally infested soil and in soil where the endospores of P. penetrans had been killed by autoclaving. After 37 weeks, the root-knot nematode population was very high in the autoclaved soil but numbers of root-knot nematode eggs and second-stage juveniles were 99% lower in the soil that was naturally-infested with P. penetrans. A subsequent pot experiment with mass-produced endospores showed that when soil contained more than 6 000 endospores/g soil, root galling was not as severe as in non-infested soil and the number of root-knot nematode eggs was reduced by 71–82%. These results indicate that when high endospore concentrations are continually maintained in the root zone, P. penetrans will markedly reduce populations of one of the most important nematode pests of sugarcane.