Susceptibility of some Australian acacias to the root-knot nematode Meloidogyne java']javanica

The susceptibility of seven Australian acacias (Acacia hilliana, A holosericea, A lysiphloia, A. mangium, A sclerosperma, A trachycarpa and A tumida) to Meloidogyne javanica has been studied with different rates of nematode inoculums (100, 500 and 1000 juveniles per pot). All these Acacia species are susceptible to the root-knot nematode. A sclerosperma, A hilliana, A holosericea and A mangium are better hosts for M javanica than A trachycarpa, A tumida and A lysiphloia. The root-knot nematode only inhibits the development of A holosericea and stimulates the growth of A tumida. A negative effect of the nematode has been measured with the nitrogen fixation with A mangium and A holosericea but, on the contrary, M javanica stimulates this symbiosis with A tumida and A hilliana. In this case. it can be calculated that 1 mg of dry weight of nodule induces 98 and 88 mg of shoot dry weight respectively.