Assessing the efficacy of alternative chemical and organic products against Meloidogyne spp. in sweetpotato

Root-knot nematodes (Meloidogyne spp.) are considered as the most serious nematode pest in the world and have been reported to cause up to 57–67 % crop yield losses in untreated conditions in Australia. Chemical control has been the most popular method to manage root-knot nematodes due to its high efficacy. However, ‘fenamiphos’ the most widely used active ingredient in nematicides, has recently been reviewed by the Australian Pesticides and Veterinary Medicines Authority and subsequently has been recommended for removal from the commercial market in Australia due to concerns about its potential to contribute to adverse environmental and human health impacts. Due to this pressure of nematicide restrictions, alternative chemical and organic formulations were assessed against root-knot nematodes in a sweetpotato field trial comparing with untreated control and chemical control ‘oxamyl’ (currently registered chemical for sweetpotato). Fluensulfone significantly reduced soil root-knot nematode numbers compared to other treatments, giving the highest marketable yield in this trial. Abamectin did not give significant root-knot nematode control or damage reduction. Organic nematicide treatments (garlic formulation and nutrient and microbial formulation) did not show a significant reduction of soil root-knot nematode numbers and root damage. No significant effect of nematicides was found on non-target organisms (soil bacteria and nematodes) at 24 weeks after planting.