TOBACCO DISEASES. Among the various dis eases of tobacco perhaps the best known is calico or mottled top, a Connecticut name for the mosaic disease of Holland. The of tobacco in Connecticut, the spot disease of Rus sia, and the niche of France are somewhat simi lar. The mosaic disease as described by Mayer, one of the first to investigate it in Holland, is characterized by mottled light and dark green leaves a few weeks after the plants are set. The tissue in the darker parts of the leaves grows faster and soon is much thicker than the light colored areas. As the disease progresses some of the thin areas die out, giving a decidedly mottled appearance to the leaf. The diseased plants are usually irregularly distributed throughout the field. The cause has been the subject of much controversy. By many observers it is said to be of bacterial origin. Others claim it to he due to certain enzymes which disturb the balance be tween the normal functions of certain cells. Beijorinck claims to have produced the disease by inoculating healthy plants with the sterilized fluid from diseased leaves. Others claim it to be due to soil and water conditions. The evidence now at hand seems to favor the theory of the un organized ferments as the probable cause. The spot disease is characterized by white or brown spots of various size and shape upon the leaves. In some cases the leaves resemble the spotted condition which is considered so desirable in some tobaccos, as the Sumatra wrapper leaf. The
cause of the spot is not definitely known. In Australia the fungus Peronospora hyoseyami produces a common and destructive disease of the plants, and in Java and Sumatra the dark spots are attributed to Phytophthora nicotiame. Both these diseases may be prevented by thorough ap plication of Bordeaux mixture. In the curing of tobacco two diseases, pole burn and stem rot, are common. Pole burn is likely to develop if long continued damp, sultry weather occurs while the plants are being cured. It first attacks the veins, turning them black, but spreads to the rest of the leaf, blackening it and making it very bitter. Certain fungi seem always present in this disease, as well as many bacteria. It is believed the fungi are the principal cause of the injury, in which the bacteria doubtless assist. This disease may be prevented by artificial heat and ventila tion. The stein rot is due to the fungus Botrytis longibrachiata. It attacks the stems and veins, producing patches of velvety white fungus and causing, more or less decay. The spores ripen upon the stalks that are thrown aside as worth less. These should he carefully collected and burned,and I he tobacco barn thoroughly fumigated with sulphur fumes before and after curing a crop.