Submitted to: Cucurbitaceae Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 6, 2002
Publication Date: December 14, 2002
Citation: THIES, J.A., LEVI, A. IDENTIFICATION OF RESISTANCE TO MELOIDOGYNE ARENARIA RACE 1 IN U.S. WATERMELON PLANT INTRODUCTIONS. CUCURBITACEAE PROCEEDINGS. 2002. p.132-137. Technical Abstract: Root-knot nematodes (Meloidogyne arenaria, M. incognita, and M. javanica) reduce yields of watermelon (Citrullus lanatus var. lanatus) in the southern U.S. and world-wide. Root-knot nematodes are controlled in watermelon by pre-plant soil fumigation with methyl bromide or treatment with other nematicides. The pending loss of methyl bromide from the U.S. market in 2005 has stimulated interest in developing alternatives for managing nematodes in vegetable crops. Host plant resistance would provide an inexpensive, environmentally safe alternative for controlling root-knot nematodes in watermelon. However, watermelon cultivars resistant to any of these species of root-knot nematodes are not available. We evaluated all accessions of C. colocynthis (21) and C. lanatus var. citroides (88), and approximately 10% of C. lanatus var. lanatus (156) accessions from the U.S. Plant Introduction (PI) Citrullus germplasm collection for resistance to M. arenaria race 1 in greenhouse tests. The C. lanatus var. lanatus accessions were susceptible [root gall severity indices (GI) range: 5.0 to 9.0 (scale: 1.0 to 9.0) except for one accession that exhibited low resistance (GI=4.9)]. All C. colocynthis accessions were susceptible (GI = 8.0 to 9.0). However, 20 of 88 C. lanatus var. citroides accessions were moderately resistant (GI = 3.0 to 4.9). These results were confirmed on 16 selected accessions representing a range of reactions to M. arenaria race 1 evaluated in a replicated greenhouse test. Results of these tests demonstrated significant genetic variability within the U.S. PI Citrullus germplasm collection for resistance to M. arenaria race 1. The C. lanatus var. citroides accessions are potential sources for increasing resistance to M. arenaria race 1 in improved watermelon cultivars.