Submitted to: Cucurbitaceae Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/16/2006
Publication Date: 9/17/2006
Citation: Thies, J.A., Levi, A. 2006. Resistance of Citrullus lanatus var. Citroides Germplasm to Root-knot Nematodes. Cucurbitaceae Proceedings. pp 380-386.
Technical Abstract: Root-knot nematodes (Meloidogyne spp.) cause extensive damage to watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus] and root-knot nematode-resistant watermelon cultivars are not available. Twenty-nine accessions from the U.S. Plant Introduction (USPI) collection of Citrullus spp. were evaluated for resistance to the southern root-knot nematode [Meloidogyne incognita (Kofoid & White) Chitwood race 3] in greenhouse tests. The Plant Introductions (PI) evaluated in these studies included: 25 Citrullus lanatus (Thunb.) Matsum. & Nakai var. citroides (L. H. Bailey) Mansf., 1 C. lanatus var. lanatus, and 3 Citrullus colocynthis (L.) Schrad. Twenty-three of the C. lanatus var. citroides PI and the C. lanatus var. lanatus PI had been previously identified as moderately resistant to M. arenaria race 1. In general, the C. lanatus var. citroides PI exhibited low to moderate resistance to M. incognita race 3 and the C. lanatus var. lanatus and C. colocynthis PI were susceptible. The C. lanatus var. citroides PI 482303 was the most resistant PI with gall index (GI) = 2.97 and reproductive index (RI) = 0.34 (1 = no galling; 5 = 26 to 38% root system galled; 9 = 81 to 100% root system galled). Significant genetic variability was observed within C. lanatus var. citroides for reaction to M. incognita, and several C. lanatus var. citroides PI may be useful sources of resistance to root-knot nematodes.