桃树叶部黑斑病病原菌鉴定及生物药剂田间防效评价

Identification of the peach leaf black spot pathogen and evaluation of the biocontrol effects of biological agents in the field

桃树叶部黑斑病是河北省桃树主要的叶部病害之一,致病病原菌种类较多,且与桃穿孔病早期症状相似,容易混淆。因此,明确河北省桃树叶部病害的致病病原菌有利于针对性地防治桃树叶部病害。本研究采集河北省桃树主要种植区典型的桃树病叶,分离纯化获得致病病原菌,利用柯赫氏法则验证病原菌的致病性。根据病原菌形态特征结合rDNA-ITS、EF-1α、Alt-al和RPB2多基因联合序列分析等分子生物学手段鉴定病原菌种类,分离获得39株菌株,明确引起河北省桃树叶部黑斑病的致病病原菌为链格孢菌(Alternaria alternata)。然后采用菌丝生长速率法测定8种杀菌剂对桃树叶部黑斑病致病菌的毒力,发现43%戊唑醇抑制效果最好,EC50值为17.661 mg/L;生物药剂16%多抗霉素、80%乙蒜素,EC50值分别为61.613和87.518 mg/L。基于室内毒力测定结果,对药剂进行了田间防治效果检测,43%戊唑醇对桃黑斑病田间防效为76.86%,生物药剂16%多抗霉素和80%乙蒜素田间防效分别为70.13%和64.93%。本研究筛选出了对防治链格孢菌具有针对性的有效药剂,其中生物药剂具有绿色无污染的特点,指导桃产业生产实践、构建不同商业桃园的绿色防控体系提供了依据。

Peach black spot is one of the main leaf diseases of peach trees in Hebei province,which is caused by diverse pathogens.And the early symptoms of peach perforation and peach black spot are easily confused.Therefore,it is necessary to identify the main pathogens infected leaves of peach trees in Hebei Province.In this study,the diseased peach leaves in the main peach growing areas of Hebei Province were collected to isolate the pathogens whose pathogenicity were verified using Koch’s postulates.The pathogens were identified by morphological characteristics combined with multi-gene sequence analysis including rDNA-ITS,EF-1α,Alt-al and RPB2.The Alternaria alternata was identified from 39 isolated strains as the pathogen causing black spot disease of peach leaves in Hebei Province.The virulence of the eight fungicides against Alternaria alternata was determined by the mycelial growth method.43%tebuconazole showed the best fungicide effect with EC50 of 17.661 mg/L.The EC50 of the biological agents including 16%polyoxin and 80%ethylicin were 61.613,87.518 mg/L,respectively.The field evaluation of 43%tebuconazole against peach black spot was 76.86%,while the efficacy of 80%allicin and 0.3%tetramycin in the field was 70.13%and 64.93%,respectively.Taken together,biological agents are safer,greener and more suitable for use in peach orchard disease control.This study provides a basis for using effective biological agents to guide production in the peach industry and to construct green control systems for different commercial peach orchards.