Abstract:
Apple rust(Gymnosporangium yamadai) was used as material, the control efficacy of six triazole fungicides against apple rust and their crop safety were studied by field experiment, in order to provide a theoretical basis for the safe and efficient control of apple rust disease.The results showed that the control effect and crop safety of myclobutanil were prominent.Field trials demonstrated that in preventive experiment, when checked 10-day after the second application during the young fruit stage, the preventive effect of myclobutanil 40% EC at 2 000 times and 4 000 times dilutions could provide 98% in protecting apple leaves from G.yamadai infection.And in therapeutic experiment, when checked 16-day post to the fourth application during the fruit swelling stages, the control effect were 90.89% and 87.17% in inhibiting the spread of leaf lesions.The results of crop safety tests showed that, when sprayed at red bud, full-bloom, fruitlet and fruit swelling stages, no phytotoxicity was found on the tested leaves, branches, flowers and fruits.While, when sprayed from the red bud stage to fruit swelling stage, all the fungicide treatments but difenoconazole 10% DC 2 000 times dilution and myclobutanil 40% EC 4 000 times dilution, the single fruit weight of other fungicide treatments decreased by more than 9% compared with untreated control.When sprayed the tested fungicides during fruit swelling stage, there was no noteworthy reduction in single fruit weight between the recommended concentration of fungicides treatments and the untreated control.