COBB'S DISEASE OF SUGAR-CANE. 37 



70 A. White striping extending from the base of the leaf to within about a foot of the top. Both edges of the leaf dead 

 from the base to 2 feet above the pricks. No secondary signs. 



70 B. White striping extending from the base of the leaf to within a foot of the top. One edge dead to within 2 feet of 



the top. 



71 A. Comparatively little white striping; extends only about 10 inches above the pricks and to the base. No second- 



ary signs. 



71 B. Diseased to within 2 feet of the top. Diseased downward to the leaf-sheath. 



72 A. Leaf diseased the whole length; a good part of it on one side, for a distance of 3 or 4 feef. No secondary signs. 



72 B. Dead, including the sheath. 



73 A. Entire leaf dried out; not only the blade, but the sheath as well. No secondary signs, i. e., as yet none of the 



uninoculated leaves arc involved. 



73 B. Can not locate the inoculated leaf. The label is on a leaf which appears not to have been inoculated. Pricked 



leaf may have fallen. 



74 A. Diseased to the apex. Dried up along both sides toward the base, and yellow on one side almost to the apex. 



Diseased condition extends down into the sheath'. 



74 B. Inoculated leaf badly diseased on both sides, nearly to the apex. Diseased condition extends nearly to the base. 



No distinct constitutional signs. 



75 A. Signs extend up a distance of 2 feet above the pricks and a few inches below. 



75 B. Narrow yellow stripes extend up a distance of more than 2 feet above the pricks and downward nearly to the 



stem. No secondary signs. 



76 A. Entire inoculated leaf dead and dried out. No constitutional signs. 



76 B. Entire inoculated leaf dead and dried out. 



77 A. Entire inoculated leaf dead. No secondary signs. 



77 B. Not found. Possibly fallen off, or removed by the gardeners. 



Louisiana No. 74. 



78 A. Very little white striping through the pricks. Some red stain. 



78 B. Tissue is white around the pricks. No general signs. 



79 A. Red stain around the pricks in the midrib and about 6 inches above. Small white stripes running through the 



pricks in the blade. No other signs. 



79 B. Red stain around the pricks in the midrib. White stripes through the pricks in the blade. No secondary signs. 



The check-pricks on these plants show no signs of disease. 



So A. Red stain in the midrib, passing through the pricks and extending about 2 inches above and below. Tissue white 

 around the pricks in the blade. No other signs. 



80 B. Red stain around the pricks in the midrib and white stripes through the pricks in the blade. No other signs. 



8 1 A. No signs. 



81 B. Slight red stain in the pricked area of the midrib. 



82 A. Slight red stain in the pricked area of the midrib. Tissue white around the pricks in the blade. No other signs. 



82 B. Same as 82 A. 



83 A. Dead stripes in the pricked area, extending upward a foot or two and downward to the sheath. 



83 B. No record. 



Common Grn. 



84 A. Signs confined mostly to the pricked area and a foot or so above it. 



84 B. Entirely dead, including most of the sheath. The leaves immediately below this and immediately above are 



alive. 



85 A. Dead stripes in the inoculated leaf, extending upward a distance of 2 feet. 



85 B. Dead stripes in the inoculated leaf, extending to the leaf -sheath and upward a distance of about a foot. 



86 A. Dead stripes in the pricked area, extending down to the sheath and upward a distance of a foot. Slight yellow 



striping further out. 



86 B. Signs less conspicuous, but dead in pricked area, and yellow stripes above and below. No constitutional signs. 



87 A. Dead striping in the pricked area, and yellow stripes with small reddish specks in them, extending upward above 



the pricked area 15 inches. 

 87 B. Much like A, but rather more diseased. No secondary signs. 



Broke off examinations here owing to the extreme heat. No constitutional signs on 

 any of these varieties. These notes are given in full because of what followed. 



This lot of cane has been examined from time to time all the summer and autumn, 

 but has shown no secondary signs of the bacterial disease, or at least none which could be 

 attributed to it beyond doubt. Now (October 9, 1905), quite a good many of the canes have 

 lost many of their lower leaves, and some of them have sprouted out at the base, but there 

 is not any distinct white striping of the uninoculated leaves which can be ascribed to the 

 disease. The canes are all tall and jammed up against the roof of the house, which is too 

 low for them. My impression is that the inoculations were made when the canes were 

 too old, and particularly after they had made a slow growth through the whole of the winter, 

 which would undoubtedly result in hardened tissues in the basal nodes, so that the bacteria 

 would have difficulty in passing from the inoculated leaves into this part of the stem and 

 into the upper and softer tissues. It was a new hot-house and it was not known that there 

 would be great inequalities in the temperature. As a matter of fact we selected the cold end 

 for the cane, but did not know it until it was too late to transplant it. 



