Descoloração em fôlhas de cafeeiro, causada pelo frio

Abstract

Submetendo-se cafeeiros novos à ação de temperaturas baixas, pouco acima de zero, determinadas fôlhas apresentaram áreas despigmentadas, de forma e extensão variáveis. Êstes sintomas se assemelham muito aos que ocorrem em certas ocasiões nas culturas, o que sugere que a temperatura muito baixa de algumas noites de inverno seja a causa dessa ocorrência.

Coffee plants growing in the field may sometimes exhibit a peculiar type of whitish or yellowish discoloration in pairs of leaves of the same age. The discolored areas are not uniform throughout the affected leaves, and in less severe cases only a strip along the leaf margins shows the symptoms. Leaves severely affected are usually smaller than normal, and may become mottled and distorted. Symptoms identical to those observed in the field were reproduced when coffee seedlings were submitted to low temperatures in the laboratory. Treatment for six hours at 3°C was enough to induce leaf discoloration, but it was noticed that conditions to which the plants had been submitted on the day prior to treatment had some influence on symptom expression. Severity of symptoms seems to be increased when coffee seedlings were treated after a clear sunny day.