16种杀菌剂对‘热研4号’王草草茎点霉菌的室内毒力测定

Indoor Toxicity Determination of 16 Fungicides to Phoma Herbarum on‘Reyan No.4’King Grass

由草茎点霉(Phoma herbarum)引起的王草叶斑病,在热带地区普遍发生,导致‘热研4号’王草生长量减少、产量降低、经济效益降低。为筛选对王草叶斑病病原菌高效低毒的杀菌剂,本研究采用菌丝生长速率法分别测定16种杀菌剂对草茎点霉菌的毒力。结果表明:25%吡唑醚菌酯EC的EC_(50)值最小,仅为0.1379mg/L,对王草草茎点霉的毒力最强;10%苯醚甲环唑WGD、325g/L苯甲·嘧菌酯SC、125g/L氟环唑SC、22.5%啶氧菌酯SC、50%咪鲜胺锰盐WP、400g/L嘧霉胺SC和430g/L戊唑醇SC的EC50值均小于1mg/L,分别为:0.3064mg/L、0.3260mg/L、0.3548mg/L、0.4657mg/L、0.5272mg/L、0.6743mg/L和0.9974mg/L,对王草草茎点霉的毒力较强;24%腈苯唑SC、25%丙环唑EC、50%多菌灵WP、50%嘧菌酯WGD、80%代森锰锌WP和50%异菌脲WP的EC_(50)值介于1~10mg/L,分别为:1.0939mg/L、1.4405mg/L、1.6659mg/L、1.9023mg/L、7.1811mg/L和9.4764mg/L,对王草草茎点霉的毒力相对较强;70%甲基硫菌灵WP的EC50值为72.4466mg/L,对王草草茎点霉的毒力较弱。75%百菌清WP的EC50值高达985.3153mg/L,对草茎点霉的菌丝生长几乎没有抑制作用。该研究结果可为王草叶斑病进一步的田间防治提供依据。

The leaf spot of king grass is caused by pathogen of Phoma herbarum,which occurs widely in tropical areas.It results in the decrease of growth,yield and economic benefits of‘Reyan No.4’king grass.In order to screen high efficiency and low toxicity fungicides against the pathogen of king grass leaf spot,toxicity of 16 kinds of fungicides to pathogen(Phoma herbarum)of king grass leaf spot was determined by the method of mycelium growth indoor.The results showed that the EC50 value of 25%pyrazoxystrobin was the lowest,which was only 0.1379 mg/L,and it had the strongest virulence to Phoma herbarum of king grass.The EC50 values of 10%difenoconazole WGD,325 g/L benzoxystrobin SC,125 g/L epoxiconazole SC,22.5%picoxystrobin SC,50%prochloraz manganese WP,400 g/L pyrimethanil SC and 430 g/L tebuconazole SC were less than 1 mg/L,which were 0.3064 mg/L,0.3260 mg/L,0.3548 mg/L,0.4657 mg/L,0.5272 mg/L,0.6743 mg/L and 0.9974 mg/L,respectively,and they had relatively strong virulence to Phoma herbarum of king grass.The EC50 values of 24%myclobutanil SC,25%propiconazole EC,50%carbendazim WP,50%azoxystrobin WGD,80%mancozeb WP and 50%iprodione WP ranged from 1 to 10 mg/L,which were 1.0939 mg/L,1.4405 mg/L,1.6659 mg/L,1.9023 mg/L,7.1811 mg/L and 9.4764 mg/L,respectively,and it had relatively strong virulence to Phoma herbarum of king grass.However,the EC50 value of 70%thiophanate-methyl WP was 72.4466 mg/L,which had weak virulence to Phoma herbarum of king grass.The EC50 value of 75%chlorothalonil WP was 985.3153 mg/L,which had little inhibitory effect on the mycelial growth of Phoma herbarum.The results provided a basis for further field control of leaf spot of king grass.