月季黑斑病病原菌鉴定及室内药剂初步筛选

Identification of the pathogen causing black spot of Chinese rose and fungicide screening for the disease control

为有效防控月季黑斑病,于2017年6-7月自运城学院花圃采集具有典型黑斑症状的月季病叶,分离纯化获得病原菌,利用形态学特征、分子生物学特征及致病性测定对其进行鉴定;同时室内测定5种常用药剂对该病原菌的防治效果,筛选能有效抑制该病原菌菌丝生长及孢子萌发的药剂。本试验共分离纯化得到12株菌株,其病原菌形态特征一致、rDNA-ITS、GPD、EF-1α基因扩增序列均相同。结合形态学特征观察以及rDNA-ITS、GPD、EF-1α基因联合构建的系统发育树将运城月季黑斑病病原菌鉴定为链格孢Alternaria alternata。在5种药剂中,50%咯菌腈和50%异菌脲各浓度对月季黑斑病病原菌的抑菌效果均较好,对菌丝生长抑制率和孢子萌发抑制率分别达到95.2%和96.6%以上;其次是70%代森锰锌,3个浓度的菌丝生长抑制率在84.1%~87.2%之间,3个浓度的孢子萌发抑制率均高于93.5%,其中600倍液的孢子萌发抑制率最高,达98.1%;80%多菌灵和12.5%腈菌唑对月季黑斑病病原菌的抑制效果最差,菌丝生长抑制率和孢子萌发抑制率分别低于42.4%和46.3%。毒力测定结果显示,50%咯菌腈毒力最强,抑制中浓度EC50为25.8 mg/L;12.5%腈菌唑毒力较弱,EC50为160.3 mg/L,其它3种药剂的EC50介于30.4~60.7 mg/L之间。因此,50%咯菌腈可湿性粉剂和50%异菌脲悬浮剂可作为防治由链格孢引起的月季黑斑病的优选药剂。

In order to prevent and control rose black spot effectively, the rose leaves with typical black spot symptoms were collected from the flower nursery of Yuncheng University from June to July 2017,and then the pathogen was isolated and identified with morphology, molecular biology and pathogenicity test. In addition, the sensitivity of the pathogen to five common fungicides was tested in the laboratory, and fungicides that effectively inhibited the mycelial growth and spore germination were screened.In total, 12 strains were isolated with the same morphological characteristics, and their amplified sequences of ribosomal RNA gene and internal transcribed spacer(rDNA-ITS), glycerol-3-phosphate dehydrogenase(GPD) and elongation factor-1α(EF-1α) were identical, respectively. According to the morphological characteristics and phylogenetic tree constructed based on rDNA-ITS, GPD and EF-1α,the pathogen isolated from black spot of Chinese rose leaves in Yuncheng was identified as Alternaria alternata. Among the five fungicides, 50% fludioxonil and 50% iprodione showed better inhibitory effect on rose black spot pathogen, with the inhibition rates of mycelial growth and spore germination reaching 95.2% and 96.6%, respectively. Followed by 70% mancozeb, the inhibition rate of mycelial growth ranged from 84.1% to 87.2%, and the inhibition rate of spore germination was above 93.5% at three test concentrations, among which the inhibition rate at 600-fold solution was the highest, reaching98.1%. However, 80% carbendazim and 12.5% myclobutanil showed the worst control efficacy, with the inhibition rates of mycelial growth and spore germination lower than 42.4% and 46.3%, respectively. The toxicity test results showed that 50% fludioxonil exhibited the strongest virulence with an EC50 of 25.8 mg/L, while 12.5% myclobutanil had the weakest toxicity with an EC50 of 160.3 mg/L;the other three fungicides had EC50 values ranging from 30.4 mg/L to 60.7 mg/L. Therefore, fludioxonil and iprodione could be the primary fungicides for control of rose black spot.