新几内亚凤仙花根腐病病原菌鉴定及杀菌剂室内毒力测定

Identification of Phytopythium helicoides Causing Root Rot of Impatiens hawkeri and Toxicity Test of Different Fungicides in Laboratory

为明确引起温室栽培的新几内亚凤仙花(Impatiens hawkeri)根腐病病原菌种类,采集具有典型根腐病症状的材料通过组织分离法对病原菌进行分离和纯化,结合病原菌形态学特征及ITS、COXⅡ序列分析,确定病原菌为旋柄疫腐霉(Phytopythium helicoides)。柯赫氏法则验证表明,旋柄疫腐霉对新几内亚凤仙花具有强烈的致病性。寄主范围测定表明,该菌还可侵染凤仙花(I.balsamina)、四季海棠(Begonia cucullata)、丽格海棠(B. elatior)、天竺葵(Pelargonium hortorum)、微型月季(Rosa hybrida)、玫瑰(R.rugosa)、倒挂金钟(Fuchsiahybrida)、玉树(Crassulaarborescens)和长寿花(Kalanchoe blossfeldiana)等9种园艺植物。培养特性表明,该菌菌丝最佳生长温度为27~32℃,最佳培养pH为6~7。采用含药平板法测定了10种商品杀菌剂对病原菌的毒力,结果表明10%氟噻唑吡乙酮可分散油悬浮剂、98%噁霉灵可溶性粉剂、40%烯酰吗啉水分散颗粒剂和80%代森锰锌可湿性粉剂毒力最强。

In order to identify the pathogen of Impatiens hawkeri root rot,two pathogenic strains were isolated from diseased roots by tissue separation method. Based on morphological characteristics and ITS and COX Ⅱ sequences analysis,the pathogen strains were finally identified as Phytopythium helicoides.Inoculating the pathogen on the healthy roots,stems and leaves reproduced the heavy symptoms observed according to the Koch's rule. The determination of host range showed that P. helicoides could infect not only I. hawkeri,but also I. balsamina,Begonia cucullata,B. elatior,Pelargonium hortorum,Rosa hybrida,R. rugosa,Fuchsia hybrida,Crassula arborescens and Kalanchoe blossfeldiana. In culture tests,the optimum for mycelial growth were at 27–32 ℃ at pH 6–7. Additionally,the toxic effect of ten fungicides against pathogen were evaluated in vitro. Among them 10% oxathiapiprolin OD,98%hymexazol SP,40% dimethomorph WG and 80% mancozeb WP performed good inhibition effects.