| Turfgrass disease is difficult for turf management.At present,chemical control is still the main means of disease control.Dollar spot and brown patch are widely distributed,harmful,and they are the highest investment cost of a class of diseases,the current effective control of these two diseases still rely on chemical control.In the current chemical control of dollar spot,there is a decrease in the control effect of fungicides.Is this phenomenon caused by the common field resistance of pathogens?To solve the problem of declining effectiveness of fungicides,lawn managers rotate agents with different mechanisms of action to improve their effectiveness,and pesticide companies upgrade their products by improving production processes and adding additives.In this paper,dollar spot and brown patch will be taken as the object to evaluate the greenhouse and field control effectiveness of fungicides with different action mechanisms,so as to provide reference for the formulation of drug resistance solutions and the control to brown patch.In this study,research materials are nine S.homoeocarpa isolates from turfgrass by screen the result of in vitro fungicide sensitivity,their sensibility to thiophanate-methyl,propiconazole and boscalid are different.Preventive pot experiment are order to define the control efficacy of above three fungicides and two fungicides(fluazinam and SYP-14288)to S.homoeocarpa;The preventive effect of two kinds of products with effective ingredients of chlorothalonil and pyrimidine on brown patch was analyzed.The following results were obtained:(1)The results of sensitivity showed that four isolates of S.homoeocarpa(N7,N11,N12,N16)could still grow on the tablet with thiophanate-methyl and showed resistance to thiophanate-methyl.These isolates also showed a decrease in sensitivity to boscalid,but were still sensitive to propiconazole.The other five isolates of S.homoeocarpa(N14,N15,N18,N19,N33)were sensitive to thiophanate-methyl and boscalid,but showed a decreased sensitivity to propiconazole.According to the results of pot experiment,the 7 d control efficacy of spraying thiophanate-methyl to sensitive isolates were over 90%,the 14 d control efficacy were over 80%,significantly higher than control efficacy of resistant isolates,the 7 d and 14 d control efficacy of spraying propiconazole to high sensitivity isolates is significantly higher than control efficacy of low sensitivity isolates.the result showed that the degressive control efficacy of thiophanate-methyl and propiconazole to dollar spot is associated with resistant pathogens;There was no significant difference in the control effecacy between the highly sensitive isolates and the less sensitive isolates,which indicated that boscalid could still be used for controlling dollar spot,but the development of sensitivity should be paid close attention to.(2)The 7 d control efficacy of sparing fluazinam to nine isolates was higher than the 14 d control efficacy,average control efficacy were 94.53%and 18.15%.At the dose of 100 g/hm2,SYP-14288 has a good preventive effect on dollar spot,the 7 d average control efficacy was 78.33%and the 14 d control efficacy was 51.11%.While at the dose of 300 g/hm2 and 600 g/hm2,the preventive effect is poor.(3)At the same dose,the product with chlorothalonil as the effective ingredient has a better prevention effect on the disease than the control agent Haodishi(chlorothalonil,75%WP)and cerrocera(clonitrile,12%SC).The dose can be used for 9000 mL/hm2 in terms of the total cost and efficacy factors.There was no significant difference between the prevention and treatment of turfgrass brown patch with azoxystrobin as the effective ingredient in preventing spraying.The optimal dose was 1000 mL/hm2,and there was no significant improvement in the efficacy of the agent with or without additives. |
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