Evaluation On The Control Effect Of Three Fungicides And Their Mixtures On Fragrant Pear Tree Canker And The Synergistic Effect Of Two Elicitors

Korla Fragrant Pear is a characteristic fruit in Xinjiang and a characteristic cash crop in southern Xinjiang.However,the occurrence of fruit Valsa canker has a serious impact on the quality and yield of Korla Fragrant Pear.In this study,Valsa pyri was used as the experimental object:The control effects of three different fungicides and their two mixtures were screened and evaluated by in vitro toxicity test,in vitro branch inoculation and field control effect test;The effects of three fungicides on Valsa pyri hyphae were observed by liquid culture and scanning electron microscopy;Plant immune elicitors were mixed with fungicides in vitro and field experiments to compare the synergistic effect of elicitors on the control effect of fungicides.The results of this study are as follows:1.Evaluation of control effects of three fungicides and their two mixtures on Korla fragrant pear tree canker.The indoor virulence and field control effect of five pesticides on Korla fragrant pear tree rot were studied by mycelial growth rate method,in vitro branch inoculation method and scraping method,so as to provide a theoretical basis for the control of Korla fragrant pear tree canker in production.The indoor virulence test showed that the inhibitory effects of the five agents on the canker of Korla fragrant pear tree were different,in the order of EC₅₀ from small to large:30%pyraclostrobin·tebuconazole（SC）>27%tebuconazole·benziothiazolinone（EW）>430g/L tebuconazole（SC）>25%pyraclostrobin（SC）>3%benziothiazolinone（WG）.The results of in vitro branch inoculation test showed that the protective and therapeutic effects of the three single agents were higher than those of the two compound agents,among which 25%pyraclostrobin（SC）had the strongest protective and therapeutic effects,followed by 3%benziothiazolinone and 430g/L tebuconazole（SC）.The results of field control evaluation showed that the control effects of 3%benziothiazolinone（WG） and 430g/L tebuconazole（SC）were the strongest,followed by 25%pyraclostrobin（SC）,and the control effects of the two compounds were poor.According to the in vitro inoculation and field control effect test,3%benziothiazolinone（WG）,430g/L tebuconazole（SC）and 25%pyraclostrobin（SC）are effective agents for controlling Korla Fragrant Pear Tree canker.It is recommended to popularize them in production,and pay attention to the alternative use of agents with different action mechanisms when using them,so as to avoid drug resistance due to the use of the same agent for a long time.2.Morpho-toxicological study on three fungicides agents Valsa pyri.In liquid,Tebuconazole had the strongest inhibitory effect on Valsa pyri.Compared with the normal mycelium,the mycelium treated with benziothiazolinone showed shrinkage,thinning,constriction and distortion,increased abnormal branches and increased septum spacing,the mycelium treated with tebuconazole were slight swollen,different thickness and constricted at branches,and the mycelium treated with pyraclostrobin ether ester were broken and wilted.In summary,benziothiazolinone,tebuconazole and pyraclostrobin can inhibit the growth of mycelium and destroy mycelium to some extent.Among the three pesticides,tebuconazole had the strongest inhibitory effect on mycelial growth,but its effect on mycelial morphology was not obvious and its destructive effect was weak.The inhibitory effect of pyraclostrobin on mycelium is second only to tebuconazole,which can seriously distort the mycelium surface in a short time but with the extension of culture time,the mycelium can return to normal growth.Tebuconazole had the weakest inhibitory effect on mycelium,but had the strongest destructive effect on mycelium morphology.3.Synergism of two elicitors on the inhibition of Korla Fragrant Pear canker by benziothiazolinone.The two elicitors have obvious synergistic effect on the bactericidal effect of benziothiazolinone.On the isolated branches,the average control effect of benziothiazolinone single agent was 37.44%,the average control effect was 76.82%with the addition of chitosan and 59.71%with the addition of aminooligosaccharide.