仇芳 徐刚 谢昌平 李希 郑妃庆

摘  要：根腐病是油梨的毁灭性病害之一，该病害为害根部，引起根部变黑腐烂，严重时导致植株死亡。从发病典型的植株根部分离、纯化菌株，并开展致病性测定、形态学特征和多基因位点（ITS、LSU和COXⅡ）系统发育树分析相结合的病原菌鉴定。结果表明，引起海南油梨根腐病的病原菌为樟疫霉（Phytophthora cinnamomi）。还研究了不同培养条件和10种药剂对病原菌菌丝生长的影响。结果表明，病原菌在PDA培养基上生长较好，最适生长温度为28 ℃，最适pH为8，黑暗条件更适合病原菌的生长;烯酰嗎啉对病原菌的抑制作用最强，EC50为0.0929 ?g/mL。本研究结果为油梨根腐病的田间防控提供了一定的理论依据。

关键词：油梨;根腐病;樟疫霉

中图分类号：S436.67      文献标识码：A

Abstract： Root rot of avocado is one of the destructive diseases. The disease infects the root system of plants， causing serious black rot of roots， leading to the death of plants. The strain was isolated and purified from the roots of typical symptoms and identified by the pathogenicity test， morphological characteristics， and multi-loci （ITS， LSU， and COXⅡ） phylogenetic analyses methods. The result showed the root rot of avocado from Hainan was caused by Phytophthora cinnamomi. To clarify the biological characteristics and sensitivity to ten fungicides， the effects of different culture condition on the hypha growth of P. cinnamomi were determined， and the inhibitory activities of ten fungicides on P. cinnamomi were also studied. The results exhibited that PDA medium was the appropriate medium for hypha growth， the optimum temperature was 28 ℃， the suitable pH was 8， and continuous darkness condition was beneficial to hypha growth. The toxicity test showed that dimethomoph had the best inhibitory activity with EC50 of 0.0929 ?g/mL among the fungicides. The result could provide a theoretical basis for the field control of avocado root rot disease.

Keywords： avocado; root rot disease; Phytophthora cinnamomi

DOI： 10.3969/j.issn.1000-2561.2021.05.031

油梨（Persea americana Mill.）又名鳄梨、牛油果、酪梨和樟梨等，为樟科（Lauraceae）鳄梨属（Persea），原产于中、南美洲，属热带、亚热带常绿乔木果树[1]。其果实营养丰富、风味好，是一种高能低糖水果，可作为糖尿病人及减肥人群的保健食品。13世纪，墨西哥已开始种植油梨，20世纪初，国外开始将油梨作为商业性果树广泛种植[2]。我国于1918年开始引进种植，目前主要分布在广东、福建、台湾、云南、广西和海南等省（区）[3]。

国内外已报道的油梨病害有Phytophthora cinnamomi[4]、Armillaria tabescens、Papulaspora sp.和Ustulina sp.[5]引起的根腐病;Rosellinia neca-trix[6]、Raffaelea lauricola[7-8]、Verticillium alboa-trum[9]、P. citricola[10]、Neofusicoccum parvum[11-12]和P. palmivora[13]引起的茎部病害;Pseudomonas syringae[14]引起的树皮溃疡病;Pestalotiopsis sp.[15]引起的梢枯病;Botryosphaeria dothidea[16]、Pseudocercospora purpurea[17]、Lasiodiplodia theobromae[18]、Colletotrichum gloeosporioides、C. fructicola[19-20]和Pestalotiopsis sp.[21]引起的果实病害;Avocado sunblotch viroid[22-23]引起的日斑类病毒病。其中，根腐病是制约油梨产业快速发展的重要病害之一，而由樟疫霉引起的根腐病又是最严重的一种土传病害，具有相当强的侵染能力，该病害严重时会导致整个油梨园毁灭[24]。……