梨树根腐病病原菌的分离与鉴定及有效防控药剂筛选

[目的] 为了明确黄河故道地区造成梨树根腐病的病原菌的种类，研究18种常用杀菌剂对该病原菌的抑制效果。[方法] 通过对梨树根腐病发病根系样品病原菌的分离和单孢纯化，根据代表性菌株形态学观察、rDNA-ITS序列分析和致病性试验，进行病原菌的种类鉴定，对菌丝生长和孢子萌发有效抑制的化学药剂进行筛选，并对部分药剂进行田间防效试验。[结果] 从发病根系样品中分离纯化得到4个菌株，经形态学和rDNA-ITS序列分析，鉴定为同一致病菌；结合致病性试验结果，确定该致病菌是腐皮镰刀菌（Nectria haematococca，无性态Fusarium solani）。化学药剂筛选结果表明：72%霜脲？锰锌、1.8%辛菌胺醋酸盐和80%代森锰锌对腐皮镰刀菌的菌丝生长及孢子萌发均有良好的抑制作用；虽然80%碱式硫酸铜、3%噻霉酮、75%百菌清抑制腐皮镰刀菌菌丝生长效果较差，但对其孢子萌发具有很强的抑制作用。毒力测定与田间试验结果显示：腐皮镰刀菌对4种药剂的敏感性存在差异，95%吡唑醚菌酯和80%代森锰锌对菌丝生长的毒力最强，72%霜脲？锰锌的毒力居中，1.8%辛菌胺醋酸盐的毒力最差；72%霜脲？锰锌、1.8%辛菌胺醋酸盐和80%代森锰锌田间实际防效比95%吡唑醚菌酯好。[结论] 黄河故道地区梨树根腐病由腐皮镰刀菌（Nectria haematococca，无性态Fusarium solani）引起；室内测定和田间试验结果显示，72%霜脲？锰锌、80%代森锰锌或1.8%辛菌胺醋酸盐对梨树根腐病均具有较好的防治效果。
[Objectives] This study was designed to identify the pathogen causing root rot of pear plant in the region of the Old Yellow River Valley,and screen out the efficient chemicals from 18 fungicides commonly used. [Methods] The pathogens were isolated from the tissues of root samples of diseased pear plant and purified by the single spore culture method. The pathogens were identified according to the morphological characters,rDNA-ITS analysis,and pathogenicity tests of strains. The 18 fungicides efficient for suppressing the pathogens were evaluated by calculation of the inhibition rate of mycelium growth and spore germination,and a part of the fungicides were selected for the pathogens control in field trials. [Results] Four strains were isolated and purified from the root samples and were identified as the same pathogen by morphological characteristics and rDNA-ITS analysis. Furthermore,in cooperation with the pathogenicity test,the pathogen was determined as Nectria haematococca,and its anamorph was Fusarium solani. The results of chemical screening showed that 72% cymoxanil+mancozeb,1.8% ametoctradin acetate and 80% mancozeb had good inhibition on both mycelium growth and spore germination of Fusarium solani. Although 80% copper sulfate,3% benziothiazolinone,and 75% chlorothalonil had poor inhibition on mycelium growth,they had very strong inhibition on spore germination of Fusarium solani. The virulences of the four fungicides to Fusarium solani mycelium growth tested in laboratory showed that 95% pyraclostrobin and 80% mancozeb had the best inhibition on mycelium growth of Fusarium solani,followed by 72% cymoxanil+mancozeb,and 1.8% ametoctradin acetate was the worst. After these fungicides had been applied in field,72% cymoxanil+mancozeb,1.8% ametoctradin acetate and 80% mancozeb had better control of the disease than 95% pyraclostrobin. [Conclusions] The root rot of pear plant that occurred in