Document Type : Research Article
Author
Associate Professor of Department of Plant Protection Research, Charmahal va Bakhtiary Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Shahrekord, Iran
Abstract
Strains of Pseudomonas syringae pv. syringae (Pss) are pathogenic in various types of plants, sometimes
causing economic damage that requires chemical control. In Chaharmahal va Bakhtiary province, this
pathogen damages stone fruit trees, wheat, beans, and greenhouse plants like cucumber. This study
investigated the resistance of 62 Pss strains from different hosts to copper ions (copper sulfate) in a culture
medium. Results showed that 37.1% and 32.3% of the strains were resistant to 100 and 200 µg/ml copper
sulfate concentrations, respectively. Five copper-resistant strains from peach, almond, cherry, wheat, and
beans and one sensitive strain from cucumber, were selected for further evaluation. The effect of various
formulations containing copper compounds on inhibiting the growth of these strains in the culture medium
was assessed. All five isolates showed varying resistance to copper compounds (copper oxychloride, copper
oxide, copper carboxylate, and Bordeaux mixture). Doubling the concentration of these compounds did not
significantly affect bacterial growth. However, adding mancozeb, zinc sulfate, or iron sulfate to each copper
compound significantly inhibited bacterial growth on the culture medium. The copper carboxylate
formulation combined with mancozeb was the most effective inhibition. The CopA gene, responsible for
copper resistance, was detected in the five resistant strains and other Pss strains, confirming the results of the
experiments. In conclusion, there is resistance to copper compounds in various Pss strains. For effective
chemical control, compounds with a synergistic effect on bactericidal activity should be added to copper
compounds. The most influential formulation identified in this study for reducing the population of copperresistant Pss strains and controlling diseases caused by them is a combination of copper carboxylate or
copper oxide with mancozeb and urea.
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