Estudos sobre a mancha aureolada do cafeeiro

Abstract

The widespread halo blight onslaught on young coffee plantings in 1955 and 1956 was not repeated in the following two years except in one or two instances. Plantings that had been severely affected in those years recovered naturally. The writers had difficulty in finding a few diseased leaves in many of them. Spraying tests with two antibiotics and 15 fungicides applied approximately every five days for four consecutive months did not offer any promise of control in a severely affected planting, although a slight favorable response was observed as a result of the application of two copper compounds. Treatments aimed at modifying the nutritional status of the plants did not induce any response in the way of increasing the coffee plant resistance against halo blight. A non-identified bacteria obtained from a bean planting that showed bean halo blight-like symptons was capable of inducing halo blight on coffee. Comparative inoculation tests showed, however, that the two disease-inducing agents were not identical. The bean bacteria induced halo blight symptoms on coffee leaves indistinguishable from those caused by the coffee bacteria, but the former organism was less pathogenic to coffee and more to bean than the latter.