Determination of Fusarium oxysporum f.sp. niveum races, the causal agents of fusarium wilt, and reaction of watermelon varieties against determined races of disease in Cukurova

Adana and Mersin Provinces are important watermelon production centers of Turkey. The one of the most important disease of watermelon is Fusarium wilt caused by Fusarium oxysporum f.sp niveum.This study was conducted to determine both Fusarium races which are present in the region and the reaction of common watermelon varieties growth in the region against Fusarium wilt. Study was carried out with 25 Fusarium isolates which are derived from field surveys in 2006. Patogenisty tests showed that all these isolates can cause Fusarium wilt diseases on Sugar Baby watermelon variety. Race discrimination tests showed that 14 isolates were determined as race II, 7 isolates as race I, and 4 isolates in race 0 out of 25 isolates.The results show that all 23 tested common watermelons are susceptible to Fusarim race II, and Emperor is the most susceptible variety to race 0 (WI=33,3%) and Blade is the most susceptible variety to race I (WI=75,0%). Average diseases ratio was variable from 30,6% (Galactica) to 68,1% (Blade).