. Carnegie Institution of Washington publication. 172 BACTERIA IN RELATION TO PLANT DISEASES. into the parenchyma filling the interior of certain of these cells, while at other times they occupy only the intercellular spaces and wedge apart the parenchyma cells to form cavities. Fig. 80 b shows Bacillus musae filling one of the spiral vessels of a Fig. 80.* THE PANAMA DISEASE. In 1904, Dr. R. E. B. McKenney discovered a banana disease in Central America which had destroyed whole fields and which threatened to destroy the industry over large areas. During the next 4 years he found the
. Carnegie Institution of Washington publication. 172 BACTERIA IN RELATION TO PLANT DISEASES. into the parenchyma filling the interior of certain of these cells, while at other times they occupy only the intercellular spaces and wedge apart the parenchyma cells to form cavities. Fig. 80 b shows Bacillus musae filling one of the spiral vessels of a Fig. 80.* THE PANAMA DISEASE. In 1904, Dr. R. E. B. McKenney discovered a banana disease in Central America which had destroyed whole fields and which threatened to destroy the industry over large areas. During the next 4 years he found the disease on every banana farm in Costa Rica, meaning by this every plantation where bananas are grown in quantity for market. He also observed the disease as far south as the canal region of Panama, and from reports made to him he believes that it occurs as far north as British Honduras. The disease has probably existed in Central America for a long time, but has been destructive only within the last 10 years. During this time many large fields of bananas belonging to the United Fruit Com- pany have been entirely destroyed. Up to the summer of 1909 he believed the disease to be of bacterial origin, and thought that he had some evidence of this from pure-culture inocu- lations made in Costa Rica. But inoculations made in the hot-houses of the U. S. Depart- ment of Agriculture with his bacterial cultures have yielded only negative results. This disease first attacks portions of the rhizome. The rhizome is so large, however, that many months usually elapse before the whole of it is destroyed. The most conspicuous signs of this disease are: first, the yellowing of the leaves; then the sudden wilting and shriveling of the entire foliage. The rhizome now sends up new shoots, which appear to be healthy at first, but after a time these also perish with the same signs. In a badly diseased field one sees very few tall banana plants, but multitudes of low shoots, healthy or in various stag
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