Abstract:

To identify the pathogen of anthracnose in avocado and screen the suitable fungicides， fruit samples of Hass avocado suspected anthracnose disease from Danzhou city， Hainan province were sampled. And the pathogen was isolated and identified. The pathogenicity of strain was confirmed according to Koch’s postulate. And the sensitivity of pathogenic strain to 9 fungicides were evaluated in vitro using mycelium radial growth assay. The results showed that the 4 pathogenic strains were identified as Colletotrichum siamense according to the morphological and phylogenetic analyses of multi-locus sequences. All of 4 strains showed virulence and high pathogenicity to avocado fruits. Among 9 fungicides， prochloraz was the most effective with the mean effective inhibitory medium concentration （EC₅₀） values of 0.11 mg·L^-1， and azoxystrobin， difenoconazole， pyrazoxystrobin， penthiopyrad and carbendazim followed with mean EC₅₀ values ranged from 2.09 to 4.29 mg·L^-1. So these 6 above-mentioned fungicides exhibited strong inhibitory activities against the mycelial growth of C. siamense， which could be used as candidate agents for the control of avocado anthracnose. Above results should help in developing strategies for the management and control of anthracnose in avocado.

Key words: avocado, postharvest disease, anthracnose, pathogen identification, sensitivity to fungicides

摘要：

为鉴定油梨炭疽病病原菌并筛选合适杀菌剂，在海南省儋州收集哈斯油梨在储存期间疑似炭疽病的油梨果实，对病果的病原菌进行分离并鉴定其种类，依据柯赫氏法则对分离菌株进行致病性测定，并采用菌丝生长速率法对9种杀菌剂进行敏感性测定。结果表明，通过形态学与多基因序列分析法鉴定，4个分离菌株均为炭疽菌（Colletotrichum siamense），对油梨果实有强致病力。供试9种杀菌剂中，咪鲜胺对油梨炭疽菌的毒力最强，平均有效抑制中浓度（EC₅₀）值为0.11 mg·L^-1；其次是嘧菌酯、苯醚甲环唑、吡唑醚菌酯、吡噻菌胺和多菌灵，平均EC₅₀值为2.09~4.29 mg·L^-1，即这6种杀菌剂对油梨炭疽菌有明显抑菌效果，可作为防治油梨炭疽病的候选药剂。以上研究结果将有助于油梨果实炭疽病的管理及防治策略的制订。

关键词: 油梨, 采后病害, 炭疽病, 病菌鉴定, 杀菌剂敏感性