Research On Types Of Fungal Diseases And Control Methods Of Postharvest Diseases In Shine-Muscat Grape

Table grape is a delicious and nutritional fruit,which has very high nutritional and economic values.Table grape is one of the important commodity fruits in China.Due to thin skin and high water content,the grape is susceptible to fungal infection.Pathogens destroy the quality of grape and thus cause loss after postharvest.Studying the occurrence and development of grape fungal diseases and disease control strategies in field are the effective ways to reduce postharvest loss.Shanghai is the economic center in China,with a rapid development in grape industry.Here,Shine-Muscat grape,which is a new variety of high quality and freshness in Shanghai,was used in this study.We analyzed the type of fungal diseases in grape cultivation and marketing in Shanghai,especially focusing on the analysis of fungal diseases during the flowering,Young fruit stage,veraison and mature stages of Shine-Muscat grape.The different pathogen species were determined based on Koch’s rule and molecular identification.At the same time,the relationship between the latent pathogenic fungi in grape fields and postharvest diseases was investigated.Proper application of safe and environmental friendly food additive calcium propionate in the field not only effectively controls the occurrence of diseases in grape during cultivation period,but also significantly inhibits the deterioration of grape quality after a long-term postharvest cryopreservation and effectively extends preservation period.These results provide important theoretical basis and application guidance for the prevention and control of postharvest grape diseases before harvest.The main findings are summarized below:First,the brand culture of grape in Shanghai is relatively high,and the large-scale enterprises,which mainly produce a variety of grapes,already have a relatively high scale and a relatively perfect facility cultivation and sales system.However,there are still some small vineyards with poor facilities and serious diseases.Due to the scientific and systematic management and preservation methods,the quality of the grape is good in Shanghai.However,in the wholesale markets,supermarkets and fruit retail stores,fungal infection is more serious due to the lack of disease control and poor management,Alternaria spp.is the main disease in the market.Secord,the field fungal diseases of Shine-Muscat grape are downy mildew,powdery mildew,grey mildew,grapevine anthracnose,Spike-stalk disease,grape ulcer disease,grape Aspergillus rot,pythium rot and so on.The pathogenic fungal identified by morphological and molecular methods include Alternaria alternata,Colletotrichum gloeosporioides,Botrytis cinerea,Phomopsis sp.,Botryosphaeria dothidea,Neofusicoccum parvum,Aspergillus aculeatus,Aspergillus tubingensis,Fusarium chlamydosporum.Diphtheria endophytica.It was found that downy mildew and grey mould were easy to occur together at the young fruit stage.Third,the detection of latent and attached fungi in the field of Shine-Muscat grape found Alternaria spp.accounted for a large proportion,and it reached 39% in the mature stage.the detection rate of the Alternaria spp.was 40.79% in the postharvest fungal diseases of grape.It was found that the pathogen of Spike-stalk disease at flowering stage,and black spot disease at postharvest at low temperature caused Alternaria spp.,which were compared and identified in the Shine-Muscat grape.The results showed that the fungus was the main fungal disease of Shine-Muscat grape.In the same way,B.cinerea not only causes serious diseases in the flowering and chromatization stages,but also mainly attaches to the surface of Shine-Muscat grape in the vineyard.B.cinerea causes a large postharvest loss,with an incidence rate of 25.0% which depend on its strong pathogenic force,so it is one of the important diseases in the vineyard and storage and transportation of grape.It shows that the prevention of postharvest diseases should start from the pre-harvest to control postharvest disease.Forth,as a food additive,calcium propionate has a significant effect on the antifungal effect of B.cinerea.Under acidic conditions,the effect of inhibition was gradually enhanced as the p H value decreased.Calcium propionate with a p H of 5inhibited the germination of spores.By comparing the effects of different calcium salts,different propionate and propionic acid on the growth of grey mould colony,it was found that calcium propionate at low p H value had the same inhibition capacity as propionic acid,while calcium ion had less effect.In vivo experiments proved that calcium propionate can protect the wounded grapes and tomatoes against the infection of grey mould.It was found that calcium propionate could destroy the structure of mycelia under the microscope,and then it was found that calcium propionate could destroy the cell membrane of mold spores in the fluorescence observation by staining the spores with fluorescent dyes propidium iodide.Fifth,to control postharvest diseases of grape from the origins,we sprayed calcium propionate solution with concentrations of 0.5%,1%,1.5%,respectively,to grape fruits at different stages of pre-harvest,including 60 days after flowering,90 days after flowering,120 days after flowering,and 3 days before harvest.Furthermore,statistical analysis of field dehiscent fruit rate and incidence,as well as incidence and grape quality during post-harvest storage and transportation was conducted.We found that spraying calcium propionate on 60 days after flowering not only reduce the fruit dehiscent rate during the early stage of veraison,but also reduce the incidence in the field.All of different concentrations of calcium propionate can significantly reduce the occurrence of black spot disease and gray mold disease,fruit shatter rate of grapes stored at low temperature for 80-90 days in postharvest,and can also inhibit the degradation of titratable acid and total soluble solids.The control of postharvest diseases of grapes needs to start from the field.Application of 0.5-1.5% calcium propionate solution of p H=5 in the field can be used as a safe and environmentally friendly preservative and fresh-keeping measure for postharvest grapes,so as to effectively control the deterioration of grape quality after postharvest.