Fusarium oxysporum f.sp. niveum (Fusarium wilt of watermelon).

Fusarium wilt of watermelon occurs throughout the world and is often a limiting factor in watermelon production. In China, 20-30% of watermelon production is normally lost in infested areas, and 100% mortality has been observed in fields planted with susceptible cultivars in Zhejiang Province (Lin, 1990). In a survey of 62 watermelon crops grown in plastic tunnels throughout the main production area of Cyprus, Fusarium wilt was found in all fields sampled despite the use of resistant cultivars (mainly Crimson Sweet). Mean incidence ranged from 37 to 70% in 1985 and 1986, and mean yields of marketable fruit were 38 and 10 t/ha, respectively (Ioannou and Poullis, 1991). In Aydin Province, Turkey, incidence ranged from 0.2 to 12% in fields in which the pathogen was isolated from symptomatic plants (Erİncİk and Döken, 2018). In Spain, in soil infested with unidentified races of F. oxysporum f.sp. niveum, yield loss in a triploid cultivar was 42 to 68% (Miguel et al., 2004). In South Carolina and Georgia, USA, yield losses in research fields naturally infested with race 2 averaged 62 and 83%, respectively, which represented a 91 and 55% loss in net returns per hectare, respectively, based on an average price of $USD 0.35 per kilogram of seedless watermelon fruit.