Development And Utilization Of A New Protective Agent For Apple Ring Rot

Apple Ring Rot,also known as ring rot disease,is prone to occur under conditions of high temperature and frequent rainfall and mainly affects fruits and branches.The current control method of apple ring rot is mainly chemical control.Chemical pesticides not only pollute the natural environment but also easily lead to pesticide residues and thus endanger people’s health.Therefore,the use of plant-derived pesticides,which are harmless to humans and friendly to the environment,instead of some chemical pesticides to control apple diseases has become an urgent need in production.In this study,botanical fungicides were used as test materials to investigate the inhibitory effect of several plant-derived inhibition volatiles on the apple ring rot by using the mycelial growth rate method,in vitro inoculation method,and spore germination method to verify the inhibition effect and mechanism of 4-Ethylphenol and4-Propylphenol on Botryosphaeria dothidea,and the results are as follows:1.4-Ethylphenol and 4-Propylphenol can effectively inhibit the mycelial growth of mycelia of Botryosphaeria dothidea fungus,and the inhibition effect is more obvious with the increase of the concentration of the agent.When the concentration of 4-Ethylphenol reached60 mg/L,it could completely inhibit the growth of Botryosphaeria dothideam;when the concentration of 4-Propylphenol reached 80 mg/L,it could also completely inhibit the growth of Botryosphaeria dothideam.The results of the inhibition time test showed that at the lowest inhibitory concentration,4-Ethylphenol and 4-Propylphenol completely inhibited mycelial growth in the first 24 h,and began to slightly decrease after 24 h.The inhibition of4-Ethylphenol and 4-Propylphenol on mycelial growth of Botryosphaeria dothidea did not decrease significantly within 60 h.After 60 h,the inhibition of mycelial growth of Botryosphaeria dothidea by 4-Ethylphenol and 4-Propylphenol remained above 85%.2.4-Ethylphenol and 4-Propylphenol significantly inhibited the germination of Botryosphaeria dothidea conidia and completely inhibited the germination of Botryosphaeria dothidea spores at the lowest inhibitory concentration.3.4-Ethylphenol and 4-Propylphenol changed the mycelium morphology of the Botryosphaeria dothidea.In comparison,the mycelial growth after 4-Ethylphenol treatment was disorganized,with uneven growth thickness,thin tip,deformed distribution of mycelium and disorganized branching.After 4-Propylphenol treatment,the mycelium was relatively less branched and the mycelium growth was disordered.The mycelium treated with 4-Ethylphenol and 4-Propylphenol was stained,and the nucleus of the mycelium was found to fluoresce red under fluorescence microscope,indicating that the cell membrane was damaged,which proved that 4-Ethylphenol and 4-Propylphenol were used to achieve the inhibition effect by destroying the cell membrane of the mycelium of Botryosphaeria dothidea.The conductivity values,DNA and protein leakage of mycelium cultures treated with 4-Ethylphenol and4-Propylphenol were significantly higher than those of the control group,and the leakage was greater with the increase of 4-Ethylphenol and 4-Propylphenol concentrations.4.4-Ethylphenol,4-Propylphenol and carbendazim could effectively inhibit the disease of fruits infested by Botryosphaeria dothidea.4-Ethylphenol treatment group had the best effect compared with other treatment groups,which could completely inhibit the disease of fruits at the lowest inhibitory concentration without browning,and the inhibitory was stable.