Study On Walnut Anthracnose Disease Control Effect Of Different Walnut Shell Wood Vinegar

Walnut(Juglans regia L.)is an important economic forest species,and walnut anthracnose seriously threatens walnut production.In order to obtain more ecologically safe botanical fungicides and ensure the healthy development of the walnut industry and products,this study compared the effects of walnut shell wood vinegar prepared by two refining methods,static and vacuum distillation,on the mycelial growth and spore germination of Colletotrichum gloeosporioides through indoor experiments.The best refined wood vinegar solution and application method were further determined through field efficacy control experiments,and differences in the main chemical components of refined wood vinegar and microbial diversity of walnut were measured.The results were as below.1.The static refined walnut shell wood vinegar density of 1.09 g/mL,pH 2.85,refractive index of 9.40%,total acid content of 65.81 g/L,total phenol content of 0.25 mg/mL,and dissolved tar content of 2.91%.After static and vacuum distillation,the physical and chemical properties were tested,and the results are as follows:density 1.01～1.02 g/mL,pH 2.26～2.29,refractive index 4.53%～4.87%,total acid content 52.92～57.63 g/L,total phenol content 0.22～0.25 mg/mL,and dissolved tar content of 0.04%～0.09%.After vacuum distillation,the color of the wood vinegar solution changes from reddish brown to light yellow,and the odor becomes slightly acidic.The density decreases by 6.42～7.34%,the pH decreases by 19.65～20.70%,the refractive index decreases by 48.19～51.89%,the total acid content decreases by 12.43～19.59%,and the dissolved tar content decreases by 96.91～98.63%.The total phenol content of the wood vinegar solution under static vacuum distillation at 55～75℃decreases by 8～12%,except that the total phenol content of the wood vinegar solution under static vacuum distillation at 85℃,which does not decrease.2.The inhibitory effect of wood vinegar on the spore germination and mycelial growth of C.gloeosporioides is affected by different refining conditions.The highest inhibition rate of spore germination is achieved when the static refined wood vinegar is diluted 10～40 times,reaching 100.00%.When diluted 40 times,the inhibition rate of mycelial growth is 33.23%,which is significantly higher than other dilution ratios.Wood vinegar refined by vacuum distillation at different temperatures and dilution ratios showed that the highest inhibition rate of spore germination was achieved at 55℃ and 150 times dilution,reaching 97.97%,which was significantly higher than other vacuum distillation wood vinegar solutions.After being diluted 150 times at 65℃ under reduced pressure distillation,the inhibition rate on mycelial growth was the highest,reaching 75.32%,and the inhibition rate on spore germination was also above 91.30%,showing significant differences from other dilution ratios.3.Gas chromatography-mass spectrometer(GC-MS)was used to analyze the differential components in 65℃ and 85℃ vacuum distilled wood vinegar.A total of 51 components were detected,including amines,acids,and ketones,the relative contents of these components in the two types of wood vinegar were 74.47%and 72.95%,respectively.The top five relative content increases in 65℃ vacuum distilled wood vinegar compared to 85℃ vacuum distilled wood vinegar were citric acid(100.00%),tranexamic acid(71.54%),L-pyroglutamic acid(50.00%),aspartic acid(50.00%),and pentadecane(20.00%).4.The control effect of refined wood vinegar solution in the field on walnut anthracnose disease was showed,and it was found that diluting 150 times 65℃ vacuum distilled wood vinegar had a control effect of 51.97%and 46.90%on the leaves and fruits of walnut anthracnose,respectively,which was not significantly different from prochloraz.Additionally,spraying wood vinegar can increase the richness and diversity of microbial communities in walnut leaves,fruits,and soil.Compared with sterile water,the dominant fungal phyla in leaves was Ascomycota,the dominant bacterial phyla in leaves was Dioszegia,and the dominant bacterial phyla in leaves was Proteobacteria,the dominant fungal phyla in leaves was Deinococcus.Ascomycota was the dominant fruiting fungus,and the species groups of Mycosphaerella and Capnodiales increased significantly.The dominant fruiting fungus is Proteobacteria,Cyanobacteria and Oxyphotobacteria were significantly increased.Ascomycota is the dominant fungal phylum in soil,and the species group of Sordariomycetes has significantly increased.The groups of soil bacterial community that have significantly increased are Firmicutes and Bacillales.