不同杀菌剂对苹果果实疫腐病的防治效果

Effects of several fungicides on controlling apple Phytophthora rot caused by Phytophthora cactorum

【目的】筛选防治苹果疫腐病的有效杀菌剂。【方法】采用先施药后接种和先接种后施药的方法,在室内离体‘富士’苹果果实上测试了13种杀菌剂保护果实免受疫腐病菌侵染的保护效果和抑制病菌在果实内生长扩展的内吸治疗效果。【结果】所测试的13种杀菌剂都能有效保护果实防止疫腐病菌侵染,保护效果达100%;其中,氟菌·霜霉威、噁霜·锰锌、烯酰吗啉、氰霜唑、吡唑醚菌酯、双炔酰菌胺和霜脲·锰锌7种杀菌剂的保护效果可维持10 d以上,其余6种药剂的保护效果可维持5 d以上;当疫腐病菌侵入果实后,13种杀菌剂都不能有效抑制病菌的生长扩展,防止果实发病,没有内吸治疗效果。【结论】所测试的13种杀菌剂在病菌侵染之前喷施都能有效阻止病菌侵染,持效期不短于5 d,在病菌侵染之后施用则都不能有效抑制病菌扩展致病。

[ Objective ] Apple Phytophthora rot, caused by Phytophthora cactorum （Leb. et Cohn.） Schrot, is an important disease on apple fruit in China. The disease caused fruit decays, reduced the yield and re- duced the income of apple orchards. In order to screen effective fungicides, protective and systematic ef- fects of 13 fungicides on controlling apple Phytophthora rot were tested on detached fruits by applying the fungicides before and after inoculated with zoospore suspension of P. cactorum. [ Methods ]The pathogen of P. cactorum was isolated with CA mediums from Phytophthora rot fruits, sampled from an orchard in Jincheng town, Laizhou city, Shandong province in July, 2013. Mycelia of the isolates were cultured in V8 mediums for 3-4 days, in Vs liquid mediums for 3 days and in sterilized water for 2 days to induce zoospo- rangia. Zoospore suspension was made by placed the zoosporangia in 4 ~C for 1-2 hours. Fresh ＇Fuji＇ ap- ple fruits, sampled from July to October from an orchard never applying fungicides in the growth season, were used for the fungicide test. For the protective effects, fungicides with the recommended dosages by the manufactorys were sprayed to fresh apple fruits with a hand sprayer. At the time of 1, 3, 5 and 10 days after applying fungicides, the fruits were taken out and inoculated by spaying zoospore suspension. The in- oculated fruits were immediately put into several boxes with saturated humidity （RH= 100%）. The boxes were sealed and transferred into an incubator with temperature set to 25 ℃. Three fruits were inoculated for each fungicide at each time. Lesion number was recorded after the fruits showed symptoms. For system- atic effects, the fruits were firstly inoculated by spraying zoospore suspension, then put into boxes with sat-urated humidity and incubated at 25 ℃ for 24 and 72 hours. The fruits were taken out and sprayed with fungicide and then put back to the boxes for further incubations. Three fruits were sprayed for each fungi- cide at each time. The percentage of lesion area on each fruit were recorded when the lesion number no longer increased. ANOVA was used to compare the different significance in protective and systematic ef- fects of the 13 fungicides with control. [ Results ] Examined at the 15 day after inoculation in the protective effect test, the average number of lesion per fruit inoculated one day after applying fungicides were 2.08 for the water treatment （control） and zero for the 13 fungicides treatments. The protective effects of the 13 fungicides were 100%. Lesion number per fruit inoculated three days after applying fungicides were 2.42 for control, 0.6, 0.13 and 0.07 for Hymexazol, Propamocarb Hydrochloride and Cymoxanil mancozeb, re- spectively; and zero for the other 10 fungicides. When inoculated at 5 day after spraying fungicides, lesion number were 1.65 per fruit for control, 0.53 and 0.64 for Hymexazol and Propamocarb Hydrochloride, which didn＇ t show significant with the control, and zero or near zero for other 11 fungicides. When inocu- lated at 10 day after applying fungicides, lesion number were 1.63 per fruit for control, and zero for the 6 fungicides, which were Fluopicolide-propamocarb, Oxadixyl mancozeb, Dimethomorph, Cyazofamid, Pyra- clostrobin and Mandipropamid. Examined at the 11 day after inoculation in the systematic effect test, the average percentage of lesion area per fruit sprayed water （control） were 42.88% and 62.31% for the treat- ments applyed fungicides at 24 h and 72 h after inoculation respectively. Lesion areas were between 18.33% and 40.83% for the 13 fungicides when applied at 24h after inoculation, which didn＇t show signif- icant difference with control. Lesion area were between 26.39% and 61.67% for the 13 fungicides when sprayed at 72 h after inoculation, which didn＇t show significant difference as well. [ Conclusion ] All of the tested fungicides can effectively protected the fruits and prevented the pathogen infection when applied before the pathogen infection, but can＇ t effectively inhabit pathogen extension and prevent the infected fruits from showing symptoms when applied after the pathogen infection. The protection effects of Fluopic- olide-propamocarb, Oxadixyl mancozeb, Dimethomorph, Cyazofamid, Pyraclostrobin, Mandipropamid and Cymoxanil mancozeb can last for more than 10 days.