ARS | Publication request: Reaction of Wild Watermelon Germplasm to Southern Root-Knot Nematode in South Carolina

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2008
Publication Date: July 26, 2008
Citation: Ariss, J., Thies, J.A., Kousik, C.S., Hassell, R.L. 2008. Reaction of Wild Watermelon Germplasm to Southern Root-Knot Nematode in South Carolina. Phytopathology. 98:S14.

Technical Abstract: Southern root-knot nematode (Meloidogyne incognita, RKN) can be a major limiting factor in watermelon (Citrullus lanatus var. lanatus) production in southern regions of the US. Wild watermelon (Citrullus lanatus var. citroides) populations have been identified as having higher resistance to RKN than commercial watermelon in greenhouse studies. Selected wild watermelon populations showing varying levels of RKN-resistance were further evaluated in an artificially infested field site in 2006 and 2007. In 2006, 19 experimental germplasm lines derived from USDA-ARS Germplasm Resources Information Network plant introduction accessions were compared with susceptible check populations. Two wild watermelon populations exhibited significantly less root galling than susceptible check populations and three additional populations were identified as possessing other favorable resistance traits. These five best performing wild watermelon experimental lines were evaluated at the same field site with and without pre-plant methyl bromide fumigation in 2007. In general, the experimental lines performed similarly with and without methyl bromide fumigation in regard to RKN resistance characteristics. Overall, the five Citrullus lanatus var. citroides populations exhibited less root galling, reduced RKN reproduction, and increased root vigor compared to susceptible checks. Results from these two studies suggest wild watermelon populations may prove a useful source of resistance to RKN, either as breeding material or as rootstock for commercial watermelon cultivars.