Progress of bacterial leaf spot of pepper starting with different initial quantities of infected seedlings and treatment with the use or not of copper oxichloride

Margarida Goréte Ferreira do Carmo Dirceu Macagnan Aldir de Oliveira de Carvalho About the authors

The progress of pepper leaf spot was examined starting with different initial quantities of infected seedlings (0; 3.3; 10; and 100%), treated or not with chemical control through the weekly application of copper oxichloride (2.4 g of i.a/L of water). Five experiments were undertaken in Seropédica (Rio de Janeiro, Brazil) in different time periods from June, 1996 to September, 1999. The intensity of disease was quantified regularly through visual estimation of disease severity (leaf area with lesions and leaf loss). The values for the area under the disease progress curves were calculated (AUDPC/number of days). The data was subjected to analysis of variance (p<0,01) and simple linear regression analysis was employed for the values of AUDPC/day in function of the initial quantity of infected seedlings. The reduction of initial inoculation had a direct affect on the final severity of disease, which was more stricking under the most favorable conditions for disease development. The efficiency of copper fungicides was variable. In the majority of cases, copper fungicides were not efficient, especially during the periods most favorable to the epidemics. As temperatures became higher, reduced efficiency was observed.

Capsicum annuum; Xanthomonas campestris pv. vesicatoria; epidemiology; chemical control


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