Evaluation of the Efficacy of Some Chemical Compounds in the Control of Peach Bacterial Canker

Bacterial canker caused by Pseudomonas syringae pv. syringae (Pss) is one of the most important diseases of peach and the use of  chemical pesticides in the control of the disease is inevitable. To determine the most effective formulation of copper bactericides, an experiment was conducted, during 2018-2020, in the form of a randomized complete block design with 20 treatments and 4 replications along the Zayanderood river. The treatments  used included copper oxychloride, copper oxide, copper carboxyl, bordeaux mixtures, fosetyl aluminium, urea and Zinc sulfate. Some treatments included a mixture of the above copper bactericides with urea or zinc sulfate, or both. The effect of the treatments on the incidence and severity of the disease was assessed by scaling the size of the canker in early June.. The first spraying was done in autumn after leaf fall and the second spraying was done before swelling of flower buds in winter. Three weeks after the second spraying, the population of Pss in peach buds was counted by isolation of the bacteria on the culture medium. The best formulations for chemical control of of peach bacterial canker were copper carboxyl or copper oxide plus urea and zinc sulfate compared witht copper bactericides alone. the highest efficacy was observed by copper carboxyl (78.7%), copper oxide (76%), copper oxychloride (48.1%) and Bordeaux mixture (45.6%), respectively, in terms of reducing disease severity. Fosetyl aluminium like copper oxychloride and Bordeaux mixtures, reduced disease severity level. Also, there was a statistically significant difference between application of urea and Zinc sulfate in comparison with the control (P = 0.05).