3种柑橘病原真菌对苯醚菌酯和苯醚甲环唑敏感基线研究

Baseline sensitivities of three fungal pathogens of citrus to strobilurin fungicide and difenoconazole

黑点病(Diaporthe citri)、黑斑病(Guignardia citricarpa)和脂点黄斑病(Mycosphaerella citri)在柑橘上的发生日趋严重,导致产量下降和品质变劣。尽管加强栽培管理对病害的控制具有积极的作用,但药剂防治仍然是目前这几种病害的最有效途径。苯醚甲环唑是最近登记用于柑橘病害防治的DMI(14α-脱甲基酶抑制剂,14α-demethylation inhibitors)类杀菌剂,苯醚菌酯是我国自主研发的QoI(苯醌外部抑制剂,quinone outside inhibitor)类杀菌剂,具有应用于柑橘上述病害防治的潜力。本研究从全国各柑橘产区分离获得柑橘黑点病菌菌株48个,黑斑病菌菌株46个,柑橘脂点黄斑病菌菌株50个,在含药培养基上测定抑制50%菌丝生长和孢子萌发的药剂有效剂量(EC50值)。结果表明:黑点病菌、黑斑病菌和脂点黄斑病菌菌丝生长对苯醚菌酯的敏感基线依次为0.003,0.011和0.035μg/mL,对苯醚甲环唑的敏感基线依次为0.149,0.008和0.970μg/mL,黑点病菌孢子萌发对苯醚菌酯的敏感基线为0.001μg/mL。由此可见,我国柑橘黑点病菌、黑斑病菌和脂点黄斑病菌种群对苯醚菌酯敏感,黑斑病菌和脂点黄斑病菌种群对苯醚甲环唑敏感,显示这两个药剂在防治这些病害中的潜力。柑橘黑点病菌、黑斑病菌和脂点黄斑病菌种群苯醚菌酯和苯醚甲环唑的敏感基线的确定,可以为这些药剂推广后的抗药性监测奠定基础。

Summary Melanose （Diaporthe citri）, black spot （Guignardia citricarpa ） and greasy spot （Mycospharella cirri） of citrus have been becoming more and more serious and widespread, causing significant losses to the Chinese citrus industry by reducing yield and fruit quality in recent years. Although the improvement of cultural practices has the positive effect, application of fungicides is still the primary and effective means to control these diseases. Difenoeonazole（belong to 14a-demethlylation inhibitors, DMIs） is a fungicide recently registered for use on citrus in China. ZJ0712 （belong to strobilurin, QoI）, developed independently by our country, has a high potential in controlling citrus fungal diseases. The objective of this study was to establish the baseline sensitivity of these citrus fungal pathogens to these fungicides prior to their widespread use. Forty-eight single-spore strains of D. cirri, 46 strains of G. citricarpa and 50 strains of M. citri were collectedfrom main citrus-producing regions in China. The effective dose to reduce mycelial growth or spore germination by 50%（EC50 values） of each strain was determined by using eight different concentrations of fungicides. The results demonstrated that the baseline sensitivities for mycelial growth of D. cirri, G. citricarpa and M. cirri to ZJ0712 were 0. 003, 0. 011 and 0. 035 μg/mL, respectively; to difenoconazole were 0. 149, 0. 008 and 0. 970 pg/mL, respectively. The baseline sensitivities for conidial germination of D. citri to ZJ0712 was 0. 001 μg/mL, but〉 25μg/mL to difenoconazole. These results above indicated that the populations of D. citri, G. citricarpa and M. citri were sensitive to ZJ0712, and the populations of G. citricarpa and M. citri were sensitive to difenoconazole, implying widely potential usage of these fungicides in controlling the diseases above. Determination of the baseline sensitivities of D. citri, G. citricarpa and M. citri should also facilitate the detection and verification of pathogen resistance development to ZJ0712 and difenoconazole.