Integrated pest management of nematodes in sweetpotatoes

Abstract

The Australian sweetpotato industry ($90M farm gate value) is heavily impacted by plant-parasitic nematodes, costing an estimated $20M per year in losses (ASPG pers. com.). Root-knot nematodes (RKN) are widely distributed throughout the sweetpotato-growing areas of Queensland and northern NSW. Feeding activity affects root initiation, causes stunting, skin damage and yield loss. At project commencement there was one registered chemical (S7 classification being removed from the market) and one minor use permit for RKN control. Thus, it was crucial to find alternative control methods through soil health improvement and Integrated nematode management.

The project completed the first comprehensive nematode species survey undertaken on sweetpotato producing soils in Australia, with 85 fields sampled in an initial survey. Growers now have a greater understanding of the plant-parasitic nematodes causing yield loss and damage. A new detection of reniform nematode was made outside of the previously known range. Following the detection of guava root-knot nematode into Australia a pest alert fact sheet was produced for the industry. Experiments provided new knowledge on the effects of nematode species on sweetpotato cultivars. Results suggested that R. reniformis damage occurs at root formation resulting in fewer roots, infection with RKN (M. javanica) reduced both the number and weight of roots, and the cultivar Bellevue is moderately susceptible to M. javanica (contrary to existing information)