| Watermelon (Citrullus lanatus Matsum. et Nakai) is one of annual sprawl herb plants belonging to Citrullus,Cucurbitaceae.most of china can plant watermelon. Henan. Shandong. Anhui. Jiangsu. Hubei. Yunnan, Guangxi, Hainan etc ground as production area of Watermelon. Hainan which in the south tip of china, Due to richly endowed nature geographic and climatic advantages. Hainan province has become watermelon production area one of the burgeoning commodity and turn over production base of seasonal watermelon in China, in recent years, by the need of market, the production area were was continuous increaseing in Hainan Province. But the diseasese of watermelon become one of the limiting factors for industrial development. The study of fungous diseases of greenhouse watermelon is not completely. Aiming at this issue, a more comprehensive study on the fungal disease of watermelon all over the Hainan was accomplished in this program.The result of main conclusion of this thesis:1. The investigation showed that serious and widespread disease were watermelon Fusarium wilt. Watermelon gummy stem blight, and Watermelon anthracnose, watermelon powdery mildew, Alternaria cucumerina leaf blight, Curvularia lunata leaf blight, Corynespora cassiicola leaf spot and Chaetomium globosum Gray Spot of stem were minor diseasese. and Chaetomium globosum Gray Spot of stem was first reported on watermelon.2.The rDNA-ITS sequence analysis showed that:the CM110917,SY110224,HK212073were Alternaria cucumerina, Fusarium oxysporum f.sp.niveum, Chaetomium globosum and with the result of morphology detection which can confirm the pathogeny.3.The study on biological characteristics of Fusarium oxysporum f.sp.niveum showed that the mycelium grew faster which on the watermelon leaf-extract medium and watermelon pulp-squeezing medium.28℃was suitable for mycelial growth,28and30℃were suitable temperature for spore germination. pH7-9was most suitable for mycelial growth, the most suitable pH for conidia germination was6-8. The suitable carbon sources were Glucose and D-fructose. the suitable nitrogen sources were yeast extract and peptone. The light/dark alternating condition was most suitable for mycelial growth. The lethal temperature of spore was60℃for5min in water bath.The study on biological characteristics of Colletotrichum orbiculare showed the mycelium grew faster which on the watermelon leaf-extract medium. The optimum temperature for mycelial growth and spore germination was28℃and30℃, and the pH was7-9and6-8. respectively. The suitable carbon sources were maltose. L-arabinose and glucose, the suitable nitrogen sources were yeast extract, beef extract and peptone. The continuous darkness was most suitable for mycelial growth. The lethal temperature of spore was55℃for5min in water bath.The study on biological characteristics of Alternaria cucumerina showed the mycelium grew faster which on the watermelon pulp-squeezing medium, PDA+0.1%yeast medium and PSA+0.1%yeast medium.25-28℃was suitable temperature for mycelial growth.28and30℃was suitable temperature for spore germination, and the pH was has little effect on mycelium growth, the most suitable pH for conidia germination was6-10, and the germination rates of conidia up to90%. The suitable carbon source was glucose, the suitable nitrogen sources were yeast extract and peptone. The continuous darkness was most suitable for mycelial growth. The lethal temperature of spore was55℃for10min in water bath.The study on biological characteristics of Curvularia lunata showed the mycelium grew faster which on the watermelon leaf-extract medium, PDA medium, PSA medium, PDA+0.1%yeast medium and PSA+0.1%yeast medium.28℃was the suitable temperature for mycelial growth,28and30℃were suitable temperature for spore germination and the germination rates of conidia up to95%. pH7-9was most suitable for mycelial growth and conidia germination. The suitable carbon sources were Lactose and Soluble starch, the suitable nitrogen sources were yeast extract, beef extract and peptone. The light/dark alternating condition was most suitable for mycelial growth. The lethal temperature of spore was55℃for10min in water bath.4.The results showed that17fungicides were able to inhibit the growth of Fusarium oxysporum f.sp.niveum mycelium. Dichlorotetrakis50%WP had the strongest of toxcity with the minimum EC50value of0.7309μg/mL. Benzoic Azoxystrobin32.5%SC, Propiconazole Difenoconazole30%EC, Difenoconazole10%WG, Bromothalonil Carbendazim25%WP and Bromothalonil25%WP had stronger toxicities, the EC50value was1.8847to8.1610(μg/mL. Turpentine acid copper12%EC had the lowest toxicities With the EC50values of13847.6741μg/mL.The results showed that17fungicides were able to inhibit the growth of Colletotrichum orbiculare mycelium. Benzoic Azoxystrobin32.5%SC had the strongest of toxcity with the minimum EC50value of0.0180μg/mL among17fungicides. Dichlorotetrakis50%WP and Difenoconazole10%WG had stronger toxicities. with the EC50values of0.0602μg/mL and0.4715μg/mL respectively. Turpentine acid copper12%EC. Carbendazim50%WP, Thiophanate methyl70%WP had the lowest toxicities With the EC50values of3370.4894μg/mL,3495.3852μg/mL and9883.8625μg/mL respectively.5. the The results of field efficacy trials showed that with1000to1500times liquid of Benzoic Azoxystrobin32.5%SC has best control effect (up to90%), Difenoconazole10%WG, Dichlorotetrakis50%WP can control anthracnose in watermelon of greenhouse relatively worse. |
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