| dc.description.abstract | Virus diseases in coffee are hardly know due to the scarcity of sound experimental studies. They are of economic importance and their knowledge is urgently needed in view of the increased interchange of living propagation materials. The most common is the "ring spot" virus, described from Sao Paulo, consisting of concentric circles with alternating dark and clear bands. The spots are found upon leaves and fruits. Experimental trials showed that the seeds of infected trees do not transmit the disease. It was impossible also to infect healthy plants with juice inoculations, but it could be transmitted by graft. Recent work has shown that the "spotted wilt" virus of tobacco could be infected in healthy coffee plants by rubbing the leaves with the juice of virotic tobacco. The spots are similar to the "ring spot" referred above. A second virus, also discovered in Sao Paulo, is called "grease-spot". It is a clear green circle, 2-3 mm. in diameter, the tissues having the appearance of being impregnated with oil. A third type, "blister spot", was described from Costa Rica from fruits and leaves. It is also a circular, decolorized spot, often bullate it was transmitted experimentally by graft to healthy plants. Other diseases that have been attributed to virus without firm experimental proof, are the so called "crespera", in which the leaves take a characteristic crinkled aspect the "bottling disease" of East Africa, and the "sudden death" of coffee, from Angola | es_ES |
