ÃÞ »¨ ѧ ±¨ Cotton Science 2008£¬20(5)£º391-393
Study on the Synergism of Agricultural Antibiotic 120 and Carbendazim Against Fusarium oxysporum
Abstract£ºAgricultural 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 ª² 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 1¡Ã1, 1¡Ã2, 2¡Ã1 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 1000mg¡¤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¡ãC to 60¡ãC PDA medium, drugs and medium mixing, cooling to room temperature, then to 5 mm in diameter dish inoculated cotton Fusarium oxysporum block, in 25¡ãC incubator in the culture 5-7d, 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£ºwith respect to cotton wilt, inhibitory concentration of agricultural antibiotic 120 is 285.7¡«666.7mg¡¤L-1,while the carbendazim is 333.3¡«1000mg¡¤L-1.Compared with the EC50 value 574.5 mg¡¤L-1 of carbendazim, agricultural antibiotic 120 is 407.4mg¡¤L-1 and showed better performance on toxicity. And the EC50 for the compound agent of agricultural antibiotic120 and carbendazim is 223.5¡«230.9mg¡¤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 1¡Ã1, 1¡Ã2, 2¡Ã1, respectiuely. The results are all larger than 1.5 of which shows notable synergies, the SR value comes to top when the proportion is 1¡Ã2 while the lowest if 2¡Ã1 was adopted, thus the best compound proportion of the said individuals is 1¡Ã 2. The experiment provides scientific evidence for controlling cotton wilt by compound fungicide.
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