Enhancing reniform nematode management in sweetpotato by complementing host-plant resistance with non-fumigant nematicides.

The reniform nematode (Rotylenchulus reniformis Linford and Oliveira) adversely impacts the quality and quantity of sweetpotato storage roots. Management of R. reniformis in sweetpotato remains a challenge because host plant resistance is not available, fumigants are detrimental to the environment and health, and crop rotation is not effective. We screened a core set of 24 sweetpotato plant introductions (PIs) against R. reniformis. Four PIs were resistant and 10 were moderately resistant to R. reniformis suggesting these PIs can serve as sources of resistance for sweetpotato resistance breeding programs. PI 595869, PI 153907, and PI 599386 suppressed 83% to 89% egg production relative to the susceptible control 'Beauregard', and these PIs were employed in subsequent experiments to determine if their efficacy against R. reniformis can be further increased by applying non-fumigant nematicides oxamyl, fluopyram and fluensulfone. A 34% to 93% suppression of nematode reproduction was achieved by the application of non-fumigant nematicides, with oxamyl providing the best suppression followed by fluopyram and fluensulfone. Although sweetpotato cultivars resistant to R. reniformis are currently not available and there is a need for the development of safer yet highly effective non-fumigant nematicides, results from the current study suggest that complementing host plant resistance with non-fumigant nematicides can serve as an important tool for effective and sustainable nematode management.