. The cotton plant : its history, botany, chemistry, culture, enemies, and uses. Cotton; Cotton. DISEASES OF COTTON. 301 other cause. This explains why from general observation the disease is thought to appear first at a later period. From a single stalk which dies in May or June the disease may spread so that areas of consid- erable extent will be affected by the close of the season. The dead patches have no definite boundaries, but extend in all directions through the field, the black streaks and patches formed by the dead plants occasionally containing a few green plants. In passing through
. The cotton plant : its history, botany, chemistry, culture, enemies, and uses. Cotton; Cotton. DISEASES OF COTTON. 301 other cause. This explains why from general observation the disease is thought to appear first at a later period. From a single stalk which dies in May or June the disease may spread so that areas of consid- erable extent will be affected by the close of the season. The dead patches have no definite boundaries, but extend in all directions through the field, the black streaks and patches formed by the dead plants occasionally containing a few green plants. In passing through the belt where the disease is prevalent a striking contrast is observed between the areas made black by the dead plants, everywhere so con- spicuous in the fields, and the interspersed green areas of apparently healthy plants. Tbe suddenness with which plants die is governed somewhat by the atmospheric and soil condi- tions, rianters frequent- ly say that dry weather checks the disease. Dur- ing the dry weather in August, 1888, few plants were dying. In the latter part of August the rains set in, and then during intervals of sunshine large numbers of plants wilted. In June and July, 1889, it was again noticed that more plants gave the ex- ternal evidence of disease after a rainy day which was followed by warm sun- shine than during several days of dry weather. Healthy plants are fre- quently found close to diseased ones even late in the season, but it does not follow that such green plants are not affected with the disease, as has been shown to be the case by examination. For example, eight plants were found growing in a cluster, two of which had wilted, and in each case tlie taproot was covered by the mycelium. In two of the green plants the taproot contained an abundance of the fungus, and the plants would probably have wilted in a very few days. In two other cases a small amount of the fungus was found on the roots, while only a single one at that time was apparently exempt
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