Comportamento da Mancha Anular do cafeeiro no campo e sua influência na qualidade da bebida

Abstract

In this work the development of ringspot virus disease was evaluated in coffee plants in the same coffee crop, from 2003 to 2005 in Lavras, Minas Gerais State -Brazil. It was also elaborated a diagramatical scale for measuring the severity of virus disease and determining its influence in the quality of coffee drink, and the effect of miticides in the control of Brevipalpus phoenicis (Acari: Tenuipalpidae) was also investigated. The development of the ringspot virus disease was studied in coffee crops cv. Mundo Novo and Acaiá-cerrado, through visual inspection, and the diagramatical scale was constructed considering the levels 0, 9, 77, 90% of severity in grains of ripe coffee cherry. After harvest, the fruits were classified based on the diagrammatical scale, dried, processed and analyzed to determine its electric conductivity, total sugars, reducing and non reducing sugars, polyphenoloxidase activity and total phenolic compounds. To investigate the miticide effect of different products, it was used the ramdomized blocks with ten plants and three repetitions. Kelthane 480 and Dicofol were tested at 0,75 mL/L, Cyhexatin 500, at 0.5 g/L and Caligur-Azociclotin, at 0,75 mL/L, with application of 1000 L/ha. These applications were accomplished every 90 days, and plants were evaluated monthly, collecting 5 leaves, a branch of 20 cm and 10 fruits (at the harvest season) on the lower third of the 6 central plants of each fragment, with the four plants, on the edge, used as border. This plant material was analyzed at the stereoscopic microscope to evaluate the number of eggs, immature and adult Brevipalpus phoenicis. The results obtained in the field evaluation showed that that the incidence and severity of the disease in the field was directly related to the presence of mite Brevipalpus phoenicis and not to the level of disease existing in the field in the previous year. Different degrees of severity of ringspot virus disease, in the coffee fruit, induced different changes in the chemical compounds.The polyphenoloxidase activity decreased when the severity of CoRSV increased, due to the increase of the concentration of total phenolic compounds and reducing sugars, which can alter the coffee adstringency, and consequently the quality of coffee drink. In the tests with the miticides, all of them were shown efficient in the control of the vector, standing out, Cyhexatin and Dicofol.