SENSITIVITY MYCELIAL IN VITRO Cercospora beticola COPPER OXYCHLORIDE

Abstract

Cercospora leaf spot or Cercospora spot, caused by Cercospora beticola Sacc is the most common disease in the leaf beet cultivation. This study aimed to determine the mycelial sensitivity in vitro, measured by the IC₅₀ (concentration for 50% inhibition of mycelial fungus growth) of three isolates of C. beticola of sugarbeet leaves obtained in Guarapuava region (PR) to the fungicide copper oxychloride shield in controlling the Cercospora spot as well as the production of cercosporin. We tested six copper oxychloride concentrations (1260.0 ppm, 126.0 ppm, 12.6 ppm, 1.26 ppm, 0.126 ppm and 0.00 ppm of the active ingredient). The concentration of 0.00 ppm represents the control without addition of the fungicide and 1260.0 represented the recommended field dose. The assessment of mycelial growth was carried out with the aid of digital caliper, measuring the diameter of the colonies, where the fungal growth in the control treatment has reached the edge of the petri dish. The experimental design was completely randomized with three replications. As for the fungus toxicity of the tested copper oxychloride active ingredient doses, it became clear that for the three isolated IC₅₀ copper oxychloride reached sensitivity values. For analysis of cercosporin was no significant statistical difference for the different isolates and different concentrations of copper oxychloride.