Investigation of the annual growth and decline of apple scab and screening of control agents in Tianshui,Gansu Province
In order to clarify the annual dynamics of growth and decline of apple scab and screen effective pre-vention and control agents in Tianshui,Gansu Province,the rate of diseased leaves and disease index of apple scab were continuously investigated during the apple growing season in 2023,and 10 pesticides were selected for field screening.The results showed that apple scab began to infect apple trees in mid-May,reached the first peak at the end of July,and then entered a slow development period.From late August to late September,the bacteria infected the autumn shoots,reaching the second peak,and then entered the overwinter preparation peri-od of the bacteria in Tianshui area.Field control experiments showed that the control efficiencies of spraying 1,000-time diluted 25％benzoyl·pyrazolate SC,2,500-time diluted 25％pentanazole·isomycin SC,1,500-time diluted 40％fluosilazole EC and 1,000-time diluted 20％enoxime·pentazolol SC,reached 83.56％-93.12％,so these four pesticides could be used as preferred agents.The control efficiencies of 1,500-time dilu-ted 12.5％tenazolol WP,800-time diluted 25％pyrazoletherin SC,1,000-time diluted 12.5％nitribacterazole EC and 800-time diluted 40％amidine EW were lower.Those chemicals could be used as additional agents,al-ternatively used with preferred agents.In conclusion,this experiment clarified the annual dynamics of growth and decline of apple scab,screened out the effective prevention and control agents,and provided theoretical ba-sis and technical support for the effective prevention and control of apple scab.
apple scabdynamics of growth and declinedisease indexcontrol effectGansu,Tianshui
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