8种杀菌剂对9种薄壳山核桃炭疽病病原菌的毒力测定

目的 测定8种杀菌剂对9种炭疽菌（26个菌株）的室内毒力，筛选出防治薄壳山核桃炭疽病的高效药剂。 方法 采用菌丝生长速率法测定8种杀菌剂对26株炭疽菌菌丝生长的抑制作用，构建毒力回归方程，并计算EC50值。 结果 供试8种杀菌剂中，咪鲜胺和咯菌腈对所分离的9种炭疽菌（26个菌株）菌丝生长的抑制作用最强，平均EC50值分别为0.14、0.15 mg·L−1。戊唑醇对C. fioriniae、C. liaoningense、C. tamarilloi和C. americae-borealis菌丝生长的抑制作用较强（平均EC50 = 0.49 mg·L−1），但对另5种炭疽菌效果不明显（平均EC50 = 23.60 mg·L−1）。恶醚唑对C. nymphaeae、C. siamense、C. alienum、C. fioriniae和 C. coelogynes菌丝生长的抑制作用较强（平均EC50 = 0.81 mg·L−1），但对另4种炭疽菌抑制效果一般（平均EC50 = 2.00 mg·L−1）。代森锰锌对9种病原菌菌丝生长的抑制性最差，平均EC50值为42.70 mg·L−1。 结论 咪鲜胺、咯菌腈对薄壳山核桃炭疽菌具有较高的毒力，在薄壳山核桃炭疽病林间防治中具有较大的应用潜力。为避免产生抗药性，建议轮换使用咪鲜胺、咯菌腈、恶醚唑和甲基硫菌灵等杀菌剂。

Toxicity Test with 8 Fungicides Against 9 Pathogens of Pecan Anthracnose ( Colletotrichum spp.)

Objective To test the toxicity of 8 fungicides against Colletotrichum in laboratory and screen out effective fungicides to control pecan anthracnose. Method The method of comparing mycelia growth rate was used to determine the fungistasis of 8 fungicides to 26 strains of 9 Colletotrichum species, then the virulence regression equations were built, and the EC50 values for each fungicide were calculated. Result Among the 8 fungicides tested, Prochloraz and Fludioxonil showed the strongest fungistasis to mycelium growth of all trains, with an average EC50 value of 0.14 mg·L-1 and 0.15 mg·L-1, respectively. Tebuconazole had a strong fungistasis to mycelium growth of C. fioriniae, C. liaoningense, C. tamarilloi and C. americae-borealis (mean EC50 = 0.49 mg·L−1), but showed a moderate inhibitory effect on other 5 species (mean EC50 = 23.60 mg·L−1). Difenoconazole had a strong inhibitory effect on mycelium growth of five Colletotrichum species, C. nymphaeae, C. siamense, C. alienum, C. fioriniae and C. coelogynes (mean EC50 = 0.81 mg·L−1), but showed low virulence for the other 4 species (mean EC50 = 2.00 mg·L−1). The virulence of Mancozeb for the 9 pathogens was the worst, with the average EC50 value of 42.70 mg·L−1. Conclusion Prochloraz and Fludioxonil show high virulence for pecan anthracnose, and are the optimal candidates for field control against pecan anthracnose. It is suggested to use Prochloraz, Fludioxonil, Difenoconazole and Thiophanate-methyl in rotation to control pecan anthracnose effectively and avoid developing resistance.