| Xinjiang is one of the important watermelon supply base of China, with the expansion of the cultivated area in recent years, watermelon Fusarium wilt has become increasingly serious, seriously affect the safety in production of watermelon. In order to effectively control the harm of watermelon Fusarium wilt, in this paper, pathogenic species, interaction and control of pathogenic fungi from watermelon planting area were conducted in-depth research, obtained the following results:During the period of 2014-2015, 35 parts of wilt were collected in watermelon planting area from the fourth division 63 regiment, the seventh division 129 regiment, 130 regiment, tenth division 187 regiment, eighth division 145 regiment. 57 isolates were obtained by tissue separation which include 43 strains of Fusarium, accounting for 75.4%, 14 strains of Rhizoctonia, accounting for 24.6%. Morphological and molecular identification results showed that 43 strains of Fusarium were belonged to three species, namely: Fusarium oxysporum, Fusarium solani and Fusarium moniliforme. The pathogenicity test results showed that only Fusarium oxysporum could cause watermelon stem wilt.Cross infection test and resistance identification of watermelon cultivars was conducted by taking the method of irrigating root with sporule suspension. The results showed that the pathogenicity of different host plants was different, but the pathogenicity of the same host plants was the strongest from cross infection. The Fusarium strains isolated from watermelon were highly infected with watermelon, the incidence was 71.7~88.9%, the disease index was 57.7~82.6 and were weakly infected the other cucurbit and cotton. The Fusarium strains isolated from cucumber were highly infected with cucumber, the incidence was 61.1~75.9%, the disease index was 43.1~62.4 and didn’t be infected with pepper, cotton. The Fusarium strains isolated from cotton highly infected with cotton, the incidence was 66.7%, the disease index was 46.6, and infected the cucurbit, tomato, pepper, but the pathogenicity of the tomato was stronger. The results from resistance identification of watermelon cultivars showed that tested cultivars did not immune to fusarium wilt, among them 4 varieties were high resistant, which accounted for 19.1% of all, 3 varieties were susceptive, 14 varieties were moderate resistant and slightly resistant.The results of determine the toxicity of the 12 kinds of fungicides showed in laboratory that prochloraz 25% EC, thiram 50% WP, hymexazol 99% WP, fludioxonil 2.5% SC and carbendazim 50% WP showed higher effective on watermelon fusarium wilt, in which prochloraz 25% EC had the best inhibitory effect against watermelon fusarium wilt, EC50 value was 0.032 ug.mL-1. Potted trials showed that prochloraz 25% EC, hymexazol 99% WP and thiram 50% WP had better control effect, with the control efficacy of 78.71%, 68.99% and 60.40%. The results of field trials showed that prochloraz 25% EC, hymexazol 99% WP and fludioxonil 2.5% SC had better control effect, the highest control effect was 71.32% in the plot experiment.Molecular detection results showed that the minimum detectable concentration of strain genomic DNA was 1pg/uL and the minimum detectable concentration of spore was 1×104 spores/mL in duplex PCR. The system can also be applied on rapid detection of diseased watermelon tissue(roots, stems, leaves), it has some significance for the early detection of disease in the production practice. |
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