Enhancing reniform nematode management in sweet potato by complementing host-plant resistance with non-fumigant

Authors: ALAM, MD - Clemson University; KHANAL, CHURAMANI - Clemson University; ROBERTS, JOSEPH - Clemson University; Rutter, William; Wadl, Phillip

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2023
Publication Date: 1/11/2024
Citation: Alam, M.S., Khanal, C., Roberts, J., Rutter, W.B., Wadl, P.A. 2024. Enhancing reniform nematode management in sweet potato by complementing host-plant resistance with non-fumigant. Plant Disease. https://doi.org/10.1094/PDIS-07-23-1412-RE.
DOI: https://doi.org/10.1094/PDIS-07-23-1412-RE

Interpretive Summary: Reniform nematode (RN) is a serious pest of sweetpotato that significantly reduces both the quality and quantity of marketable roots. Currently, there are no known sources of host resistance to RN in sweetpotato. With all commercial sweetpotato cultivars susceptible to damage from RN, growers spend a lot of time and money applying environmentally damaging fumigant nematicides on their fields to try and control this nematode. To develop RN resistance in sweetpotato, we selected a diverse set of 24 sweetpotato plant introductions (PI) from the USDA germplasm collection and screened them in multiple greenhouse assays for resistance to RN. We identified 3 PIs with resistance to RN that reduced the number of nematode eggs by 83%-89% relative to the susceptible control cultivar Beauregard. To see how well these RN resistant PIs could be used in conjunction with more environmentally freindly non-fumigant nematicides for sustainable management, we ran additional greenhouse assays using the resistant PIs in conjunction with three non-fumigant nematicides. Our results provide evidence that combining host resistance RN with non-fumigant nematicide applications in sweetpotato could be a more sustainable approach to managing RN in the field.

Technical Abstract: The reniform nematode (Rotylenchulus reniformis Linford and Oliveira) adversely impacts the quality and quantity of sweet potato storage roots. Because host plant resistance is not available, fumigants are detrimental to the environment and health, and crop rotation is not effective, management of R. reniformis in sweet potato remains a challenge. The current study screened a core set of 24 sweet potato plant introductions (PI) against R. reniformis. Four PI were resistant and 10 were moderately resistant to R. reniformis suggesting these PI can serve as sources of resistance for sweet potato resistance breeding programs. PI 595869, PI 153907, and PI 599386 suppressed 83% to 89% egg production relative to the susceptible control Beauregard, and these PI 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 sweet potato 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.