Investigation Of The Main Diseases On Cucurbits And Vegetables Of Facilities Cultivation In Sanya And Basic Control Method For Two Important Diseases

Due to the tropical climate, unique geographical location, plenty of light and temperature, Hainan is suitable for planting off-season vegetables. Sanya is the important base of vegetable planting and the core area of vegetable breeding. Recently, Sanya pays attention to developing high-efficiency agriculture industry. Facility cultivation has rapidly developed, especially with noticeable achievement of melon facility cultivation. Cowpea facility cultivation is at starting stage now, and others are primarily for breeding. With the increasing of the areas and the variety of the cultivars of facilities cultivation, the disease control is becoming the key problem which demands to resolve.The diseases of the vegetables of the facility cultivation in Sanya were investigated, including their types, distribution and damage. Two important diseases including bacterial fruit blotch of melon and ring spot of cowpea were studied and their pathogenic identification, resistance evaluation, indoor screening of fungicides were carried out. The following results were obtained:It was the first time to conduct the disease investigation of vegetables of the facility cultivation in Sanya, and a large amount of basic data including the symptoms, distributions and damages of vegetable diseases were obtained. Thus twenty-six diseases caused by fungi, five by bacteria, one by virus and one by nematode were identified. Major investigation on melon bacterial fruit blotch and cowpea ring spot was conducted. The result indicated that in some areas of the plantation the incidence of the two diseases were reached more than60%respectively.Based on the pathogen isolation, pathogenicity determination, morphologic observation, of physiological and biochemical determination and molecular analysis, Acidovorax was found as the pathogen of melon bacterial fruit blotch. The resistance of twelve melon species to BFB was evaluated, using the method of soaking seeds and spraying seedlings. The results showed that, out of the twelve cultivars, five cultivars were middle resistant to the disease, four middle susceptible and three susceptible, and there was no highly resistant and immune cultivars. Screen assays of six chemicals to BFB were carried out in lab by the method of circle inhibition. It indicated that the effective of the six bactericides were good. Then, the chemicals were used to soaking seeds in order to detecting their seed resistance to BFB. Formalin and Guofujing No.1were screened with best control efficiency reached97.6%and94.9%respectively. Further study of the influence of two chemicals on the seed growing and metabolizing were carried out. The result showed formalin was the best chemical for seed treatment. Thus this seed treatment method of formalin has been used in winter cucurbits and vegetables breeding seedling field in Sanya of Hainan, and then the demonstration area of20acre has been established. The amount of health melons seedlings achieved more than two million per year. Among them, the living seedlings of watermelon have280thousand, grafting seedlings have860thousand, the living seedlings of muskmelon have360thousand, grafting seedlings have520thousand, and the healthy seedling emergence rate above95%.According to the pathogen isolation, pathogenicity determination, morphologic observation, of physiological and biochemical determination and molecular analysis, the pathogen of ring spot of cowpea was classified as Corynespora cassiicola (Berk.&Curst.) Wei. The resistance of nine cowpea cultivars to ring spot was evaluated, using the method of non-acupuncture inoculation and spraying spore inoculation. The result showed that, of the nine cultivars, there was one cultivar with high resistance, two with middle resistance, three with middle susceptibility and three with high susceptibility, no resistance in the nine cultivars. Screening tests of twenty fungicides indicated that10%Difenoconazole WP and50%Iprodione WP showed good inhibition against C. cassiicola, and the EC50value were2.70946mg/L and9.09327mg/L respectively, whereas75%Chlorothalonil WP and50%Carbendazim WP had poor inhibition effect, the EC50value were792.261mg/L and1329.89mg/L respectively.