Active antifungal component of extracts from Tagetes patula root against Fusarium oxysporum f. sp. niveum and its mechanism.

Bioactive components from extracts of Tagetes patula root against Fusarium oxysporum f.sp. niveum (FON) were isolated and their influence on watermelon was investigated. The results showed that the essential oil content was the highest (up to 59.8%),and its inhibitory effect on FON was the best,which was 62.83%,58.31% and 56.30% at the time point of 24,36 and 48 h,respectively. The essential oil was applied at three main infection periods of watermelon Fusarium wilt:seedling,bloom and fruit setting stage. The essential oil remarkablely inhibited the mycelial growth of FON,and promoted the growth of watermelon plant. At the same time,it enhanced the enzymatic activities of superoxide dismutase (SOD) and peroxidase (POD),maintained catalase (CAT) activity,and reduced the harm of crude toxin of FON to watermelon plant.