Diagnosis of bacterial diseases in coffee cultivation (Coffea arabica L.) and in vitro sensitivity to bactericides for agricultural use

Abstract

Coffee production is limited by pests, which reduce yields and lower quality. The objectives of this research were the identification of phytopathogenic bacteria, description of symptoms in the field and in vitro sensitivity to bactericides for agricultural use. Four coffee farms from the department of Jinotega and one from the department of Matagalpa, with a history of bacterial diseases, were selected; the tissue samples collected consisted of leaves, bandolas, fruits, and flowers. The identification of genera of phytopathogenic bacteria was carried out from the morphological characteristics of bacterial growth and the presence of fluorescent pigments in King B. The identification of bacteria species was carried out with an oxidase test and acid production tests from carbohydrates. The pathogenicity of the bacteria was evaluated by means of the hypersensitivity test in tobacco plants (Nicotiana tabacum L.) as a non-host plant. The sensitivity and inhibition of bacteria to bactericides was determined by the Bauer- Kirby method (agar diffusion method) and was evaluated in diameters (mm). The bactericides evaluated were oxytetracycline hydrochloride 5 WP, streptomycin plus oxytetracycline 16. 5 WP, oxolinic acid 20 WP and copper sulfate 24 SC. The species of bacteria identified were Pseudomonas syringae, Pseudomonas corrugata and Pseudomonas cichorii. In this investigation Pseudomonas cichorii was the most frequent in the different isolates, Pseudomonas syringae was isolated in all the coffee varieties sampled. The isolated bacterial species were positive to the hypersensitivity test, indicating that they are pathogenic for coffee cultivation. The symptoms on leaves, branchs and flowers caused by Pseudomonas spp are dark-brown spots, irregular in shape and size, generally surrounded by yellowish and translucent halos. The bactericide that showed the best effect by showing larger diameters in the bacterial inhibition halos was oxolinic acid.