Resistance to Southern Root-knot Nematode (Meloidogyne incognita) in Wild Watermelon (Citrullus lanatus var. citroides)

• Published in: Journal of nematology 2016-03, Vol.48 (1), p.14-19
• Main Authors: Thies, Judy A., Ariss, Jennifer J., Kousik, Chandrasekar S., Hassell, Richard L., Levi, Amnon
• Format: Article
• Language: English
• Subjects: Contributed Paper; plant introduction; resistance; southern root-knot nematode; var; wild watermelon
• ISSN: 0022-300X; 2640-396X; 2640-396X
• DOI: 10.21307/jofnem-2017-004

Southern root-knot nematode (RKN, ) is a serious pest of cultivated watermelon ( var. ) in southern regions of the United States and no resistance is known to exist in commercial watermelon cultivars. Wild watermelon relatives ( var. ) have been shown in greenhouse studies to possess varying degrees ofresistance to RKN species. Experiments were conducted over 2 yr to assess resistance of southern RKN in var. accessions from the U.S. Watermelon Plant Introduction Collection in an artificially infested field site at the U.S. Vegetable Laboratory in Charleston, SC. In the first study (2006), 19 accessions of var. were compared with reference entries of and var. . Of the wild watermelon accessions, two entries exhibited significantly less galling than all other entries. Five of the best performing var. accessions were evaluated with and without nematicide at the same field site in 2007. var. accessions performed better than var. and . Overall, most entries of var. performed similarly with and without nematicide treatment in regard to root galling, visible egg masses, vine vigor, and root mass. In both years of field evaluations, most var. accessions showed lesser degrees of nematode reproduction and higher vigor and root mass than and var. . The results of these two field evaluations suggest that wild watermelon populations may be useful sources of resistance to southern RKN.