农抗120与多菌灵混配对棉花枯萎病菌的增效作用研究

 . 为了开发农抗120与多菌灵混配杀菌剂新品种，在室内用平皿菌落直径法测定了农抗120与多菌灵混配对棉花枯萎病菌的联合毒力与增效作用。结果表明，农抗120和多菌灵对棉花枯萎病菌EC₅₀值分别是407.4 mg·L^-1和574.5 mg·L^-1 ，多菌灵的毒力小于农抗120；农抗120与多菌灵以1：1～2：1混配增效系数（SR）为1.99～2.19，具有显著增效作用。其中，农抗120与多菌灵1∶2混配增效系数最大，达2.19，为最佳混配增效比例。实验结果为混配杀菌剂有效防治棉花枯萎病提供了一定的科学依据。

Study on the Synergism of Agricultural Antibiotic 120 and Carbendazim Against Fusarium oxysporum

Agricultural antibiotic 120 and carbendazim are both systemic fungicide, and the premix develops a new pesticide formulation to control cotton wilt disease.This premix not only has environmental pollution-free characteristics of the biological pesticide, but also can delay the progress of pathogen's resistance to the carbendazim, significantly improve efficiency.In order to develop new effective fungicide mixed with carbendazim and agricultural antibiotic 120 to protect and treat cotton wilt, the method to determinate toxicity coeffcient and synergies of the protect and treat cotton wilt, the method to determinate toxicity coeffcient and synergies of the premix by using indoor colony diameter dish bioassay is taken. Agricultural antibiotic 120 and carbendazim by weight ratio is 11, 12, 21 for a total of 3 mixed compounds, setting up agricultural antibiotic 120, carbendazim two single dose control and a blank control, a total of six, repeated three times, the concentrations of pharmacy were between 200 and 1000 mg·L^-1  with five concentration gradients. The drugs will be different with double distilled water in five different concentration gradients in the sterile table with a straw draw 1 mL liquid (water control) into the 8 cm dish, then added 9 mL syringe melting about 50°C to 60°C PDA medium, drugs and medium mixing, cooling to room temperature, then to 5 mm in diameter dish inoculated cotton Fusarium oxysporum block, in 25°C incubator in the culture 5~7 d, the control is going to be covered dish, the colony size measurement, repeated three times, averagedly calculated pharmacy the inhibitory rate of mycelium. For the pharmaceutical concentration on the numerical variable (x), mycelium to inhibit percentage probability value of the dependent variable (y), the toxicity regression equation and the correlation coefficient (r), the regression equation obtained EC₅₀value, and the theoretical EC_(th)50  value,  mixture of different ratio coefficient of efficiency (SR) were calculated.The results showed with respect to cotton wilt, inhibitory concentration of agricultural antibiotic 120 is 285.7～666.7 mg·L^-1 ,while the carbendazim is 333.3～1000 mg·L^-1. Compared with the EC-50- value 574.5 mg·L^-1of carbendazim,  agricultural antibiotic 120 is-407.4 mg·L^-1and showed better performance on toxicity. And the EC₅₀for the compound agent of agricultural antibiotic120 and carbendazim is 223.5～230.9  mg·L^-1, which proves that the toxicity coeffcient of the compound agent is stronger than any of the individuals. The synergies indexes are 2.13,2.19,1.99 when compound agricultural antibiotic 120 with carbendazim at the proportion of 11,12,21, respectiuely. The results are  all larger than 1.5 of which shows notable synergies, the SR value comes to top when the proportion is 12 while the lowest if 21 was adopted, thus the best compound proportion of the said individuals is 12. The experiment provides scientific evidence for controlling cotton wilt by compound fungicide