Location: Vegetable Research
Project Number: 6080-22000-029-19-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2018
End Date: Sep 30, 2021
Meloidogyne enterolobii (syn. M. mayaguensis) is an emergent root-knot nematode (RKN) that is highly virulent against widely-used RKN resistant crop varieties. New tools are needed to manage this RKN in the southeastern United States to this end we have put forth 3 objectives: I. Identify useful sources of resistance to M. enterolobii in sweetpotato, pepper, cotton, and soybean. II. Identify potential non-host crops for use in rotational management strategies. III. Survey the distribution of M. enterolobii in agricultural fields across South Carolina.
1) Screening germplasm for Meloidogyne (M.) enterolobii resistance: diverse germplasm will be screened in greenhouses at the USDA, ARS, U.S. Vegetable Laboratory (USVL) (100 accessions each of sweetpotato and pepper) and at Clemson University (50 accessions each of cotton and soybean). Using well established root-knot nematode (RKN) screening techniques, selected germplasm will be inoculated with eggs produced by M. enterolobii isolates originating from South Carolina in replicated trials. After 6-8 weeks of growth, roots from each plant within a trial will be washed, scored for the level of root galling, and processed to extract nematode eggs. Galling scores and nematode reproductive efficiency scores from each line will be compared to standard susceptible control cultivars included within each experimental replicate. The potential utility of resistance will be assessed based on the relative resistance of each line compared to widely used RKN resistant cultivars from each crop. Clemson and the USVL will use different of M. enterolobii that have already been isolated from different regions of the state. We will crosscheck any germplasm identified as potentially resistant at both institutions to more broadly asses and confirm resistance. 2) Assessment of non-host crops for managing M. enterolobii: the host status of cultivars from reported non-host crops will be tested first in greenhouse trials at the USVL and Clemson University alongside vulnerable host crops. If the non-host status is confirmed, field trials will be conducted in fields known to be infested with M. enterolobii to assess the potential use of these crops to mitigate M. enterolobii numbers. Nematode numbers will be assessed using soil surveys performed by Clemson University before and after planting plots containing non-host and susceptible host crops. Relative nematode reproduction rates will be calculated and compared in replicated plots. 3) Field soil surveys for M. enterolobii: Statewide surveys of agricultural fields will be conducted by the Clemson University nematology lab. Root-knot populations will be speciated using well established morphological and DNA sequence based techniques for discriminating M. enterolobii from other RKN species. Clemson and ARS scientists will communicate with state extension agents to identify and sample fields reported to have root-knot nematode problems that have been planted or rotated with crop varieties susceptible to M.enterolobii.