Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum races 0, 1, 2, or 3, is found throughout the eastern United States. Most seedless (triploid) watermelon cultivars are susceptible to all races. In previous studies in Maryland, winter cover crops of hairy vetch (Vicia villosa) reduced Fusarium wilt. The objectives of this study were to compare Cahaba White hybrid common vetch (V. sativa V. cordata) to hairy vetch for suppression of Fusarium wilt in South Carolina and Maryland. Cover crops of the two vetches and rye (the control) were seeded in fall 2006 and 2007 in fields naturally infested with a mixture of races 1 and 2 in South Carolina and Maryland. In the spring after incorporating the cover crop biomass, seedless watermelons cv. Sugar Heart (susceptible) or Revolution (moderately resistant to race 1) were transplanted into subplots within each cover crop whole plot. Cahaba White vetch was as effective as hairy vetch in reducing incidence of Fusarium wilt. Both vetch varieties reduced wilt incidence by approximately the same degree with the susceptible as with the moderately resistant cultivar. In general, the moderately resistant cultivar yielded more fruit (by weight) than the susceptible cultivar.
Accepted for publication 23 August 2010. Published 14 September 2010.