WILT OF CUCURBITS. 



259 



lation) the pricked leaf was holding up remarkably well. The petiole was yellowish but turgid, and 

 not more than one-third of the blade was dead although it had lost nearly all of its green color and was 

 yellow. The next leaf above and the next below were beginning to be yellow but showed no wilt. 

 November 29 the vine was still alive but stunted and yellowish and losing leaves toward the base. 

 It was blossoming freely. December 3 this vine resembled 215 except that the three basal leaves 

 had shriveled and the others were not so yellow. The dwarfing of the foliage was distinct. March 4 

 (5 months after inoculation) the vine was still living but was stunted and branched and bore more 

 yellow leaves than green ones. It and all the other squash vines had resisted remarkably. 



(217.) Winter Squash var. Pikes Peak. There were no signs of the wilt until the twelfth day 

 after inoculation. Then the tip of the pricked leaf was drooping (without change of color) and an 

 area of about 2.5 sq. cm. had changed color and wilted, where pricked. Four days later there were 

 very decided signs. The entire blade of the pricked leaf was drooping and over half of it had changed 

 color, the change varying from a dull green to a yellowish. The blade of the next leaf below also 

 drooped badly. The insertion of this leaf was half an inch below that of the pricked leaf. This was 

 the only one of the squash vines which showed constitutional signs at this date (sixteenth day). The 

 twenty-third day nearly all parts of the blade of the pricked leaf and of the one below it were shriveled. 

 The blade of the next leaf up (insertion 1 inch above) was a fine green but was beginning to droop on 

 one side in the lower lobe. November 1 1 the blade of the pricked leaf was brown and dry but the 

 petiole was green and turgid. No additional leaves were affected. November 29 the vine was still 

 alive but stunted and yellowish and losing leaves at the base. It was blossoming freely. By Decem- 

 ber 3, the pricked leaf (with the exception of the base 

 of the petiole) and the cotyledons had shriveled. The 

 plant was 13 inches long and had 12 leaves. The stem 

 was yellowish and the vine was dwarfed but was blos- 

 soming freely. December 31 (nearly 2 months after 

 inoculation) the vine was still alive and, on the whole, 

 looked better than 6 weeks earlier. It had made a 

 new terminal growth, 12 to 15 cm. long, which was in 

 every way more vigorous than the stunted, terminal 

 growth which developed in the weeks immediately 

 following the inoculation. The leaves were larger 

 and of a good green and this part of the plant was 

 blossoming. March 4 the vine was stunted and dead 

 from the tip down a distance of about a foot. It had 

 put out small stunted side shoots and there were some 

 green leaves yet. 



(218.) Winter Squash var. Pikes Peak. The 

 ninth day after inoculation there was a wilted, dull- 

 green area starting from two of the pricked spots. In one, the wilted part began at one side of the 

 pricks, not including all of them, and covered an area of only 2 to 3 sq. mm. In the other the wilt now 

 covered about 2 sq. cm. and involved all of the pricked spot although the latter was excentric. Twenty- 

 four hours later the previously wilted tissue had lost water and begun to be traversed by many fine 

 wrinkles. The diseased area had increased but little. The following day there was no noticeable 

 change. The progress of the disease was very slow and on the sixteenth day not over one-eighth of 

 the pricked blade had wilted and the blade as a whole had not collapsed. Even 7 days later (October 

 28) one set of pricks (No. 3) had failed to infect and that part of the leaf was still green. The tissue in 

 the immediate vicinity of the other two sets of pricks was dry and brown. Most of the leaf was yellow 

 or yellowish green and flabby but not shriveled. The petiole was normal. The first leaf up, the 

 insertion of which was 2 inches above that of the pricked leaf, was still green but one lower lobe was 

 drooping. November 1 1 half of the pricked blade was brown and shriveled, the rest was yellow and 

 green mixed. All of it was soft, flabby. The petiole was still turgid and not very yellow. The blade of 

 the next leaf up had a yellow spot on the upper part but was not flabby in any part. No other leaves 

 were affected. November 29 the vine was stunted and yellowish and losing leaves toward the base 

 but blossoming freely. December 3 the stem was 22 inches long and bore 16 leaves, the terminal 7 of 

 which were badly dwarfed. The basal 2 leaves and cotyledons had shriveled to the stem. The foliage 

 was lighter green than that of the uninoculated plants. A month later (December 31) the vine had 

 made a new terminal growth 12 to 15 cm. long. This was of a much more vigorous character than 



*Fig. 72. Leaf of squash No. 216, inoculated with Bacillus tracheiphilus, Oct. 5, 1895, 3 p. m., in three places. 

 On Oct. 14, 3 p. m.. the shaded area had changed to a dull green and wilted. Up to Oct. 17. 3 p. m., there was no 

 distinct increase of wilt, but on Oct. 21, that part beyond the dotted line was yellowish green and drooped slightly. 

 For further changes see text. 



