88 Report of the Botanist of the 



1895. was described by H. L. Russell at the Springfield meeting 

 of the American Association for the Advancement of Science in 

 August, 1895, and later was studied extensively at the Wisconsin 

 Agricultural Experiment Station and at the Department of Agri- 

 culture at Washington. Extended accounts of the disease and 

 its cause were published by E. F. Smith in the Centralblatt fiir 

 Baktcriologie, II Abteilung, Vol. 3, and in Farmer's Bulletin 68 

 of the Department of Agriculture, as well as by Russell & Hard- 

 ing in Bulletin 65 of the Wisconsin Agricultural Experiment 

 Station. 



APPEARANCE OF AFFECTED PLANTS. 



The first evidence of disease usually appears in the latter part 

 of July when the more advanced plants of late cabbage are 

 beginning to form heads. The first symptoms of an outbreak 

 are easily recognized on a hot, dry afternoon when a number of 

 the plants will appear wilted and lighter green in color. A cross 

 section of the stem of these plants near the ground shows that 

 many of the water-carrying fibro-vascular bundles are black; and 

 on splitting the stem these black lines can be followed down to 

 the withered extremity of the tap root. A diseased condition 

 of any considerable number of these bundles curtails the water 

 supply and when atmospheric conditions are favorable for rapid 

 evaporation from the leaves the latter cjuickly wilt. 



The upward movement of the water carries the disease along 

 the bundles out into the leaves. As soon as the bundles supply- 

 ing any considerable portion of a leaf become diseased that part 

 of the leaf dies for lack of water. The blade of the leaf becomes 

 light brown and has a texture like parchment. It is semi-trans- 

 parent and when closely examined the network of fine veinlets 

 which have been turned black by the disease stands out sharply 

 in the brown background. 



Early in August the disease connnonly manifests itself in another 

 form. Brown spots appear at the margin of many of the leaves 

 (see Plate I) especially of those which come in contact with the 

 soil. These brown areas spread toward the center of the leaf 

 and a close examination shows the fine veins to be blackened. 

 In from one to three weeks, depending on circumstances, the 



