Abstract:

In order to select effective fungicide for the control of alfalfa rust, 14 kinds of fungicides toxicity were measured using potted plant and spray method to study the synergitic effect, and 6 kinds of fungicides of mixed formulation were selected. The test results indicated that Azoxystrobin had the strongest toxicity to alfalfa rust and EC₅₀ was 1.8809 mg·L^-1, Thiophanate-methyl had the weakest toxicity and EC₅₀ were 747.0022 mg·L^-1. According to the different mechanisms of fungicides, the 1:9 formulation of Azoxystrobin mixed with Tebuconazole produced an additive effect, the 5:1 formulation had the strongest synergistic effect and efficiency coefficient was 4.9684. The 1:3 formulation of Azoxystrobin mixed with dimethomorph produced the strongest synergies and efficiency coefficient was 5.1114, but 9:1 formulation produced antagonism effect. The 1:7 formulation of Azoxystrobin mixed with mancozeb produced obvious synergies and efficiency coefficient was 4.5757. The 1:5 formulation of Pyraclostrobin mixed with difenoconazole produced the strongest synergy effect and efficiency coefficient was 5.2276. The 1:7 formulation of Pyraclostrobin mixed with chlorothalonil produced obvious effect and efficiency coefficient was 5.8058.

Key words: Alfalfa rust, Fungicide, Selecting, Mixture, Toxicity test

摘要：

为了筛选防治苜蓿(Medicago sativa)锈病有效单剂和复配组合,本试验采用盆栽喷雾法,测定了14种杀菌剂及5种复配剂对苜蓿锈菌的毒力,并比较不同复配的协同增效作用。结果表明:在单剂毒力测定中,苜蓿锈菌对嘧菌酯最敏感,EC₅₀为1.8809mg·L^-1;甲基硫菌灵的毒力最弱,EC₅₀为747.0022mg·L^-1。按照不同杀菌机理的药剂复配机理,嘧菌酯和戊唑醇复配中,1:9组合产生相加作用,其余比例复配均表现为增效作用,其中5:1增效作用最强,增效系数SR为4.9684;嘧菌酯和烯酰吗啉复配,协同增效作用最强的是以1:3组合,增效系数为5.1114,但二者以9:1复配时产生拮抗作用;嘧菌酯和代森锰锌复配,1:7复配组合增效系数SR为4.5757,协同增效作用比较明显。吡唑醚菌酯与苯醚甲环唑复配增效作用最强的是1:5复配组合,其增效系数SR为5.2276;与百菌清的复配,1:7复配组合增效作用最为明显,其增效系数SR为5.8058,因此,从单剂防效看嘧菌酯和吡唑醚菌酯效果最好,复配剂中,吡唑醚菌酯和百菌清以1:7防效最好。

关键词: 苜蓿锈病, 杀菌剂, 筛选, 复配, 毒力测定