WILT OF CUCURBITS. 277 



next afternoon (2 p.m.) there was wilted tissue in and around the pricked portion, covering an 

 area of about 5 sq. cm. Two days later the wilt involved about 10 sq. cm. and reached nearly half-way 

 to the middle of the blade. The leaf was now cut away with a- hot knife close to the stem. The 

 seventh day after the removal of the leaf (eighteenth day after inoculation), the first leaf up hung 

 down flabby and the blades of the next three above drooped. Five days later more leaves were 

 wilted. 



(361.) This plant was 13 inches high. The sixth leaf was inoculated 7.25 inches from the stem. 

 Its blade was 4.5 inches broad. The sixth day there were no signs of the disease but the following 

 day at noon there was a wilt of about 3 sq. cm. in and around the pricked part. Two days later 

 (2 p.m.) the wilt included about 8 sq. cm. and reached half-way to the base of the blade. The 

 leaf was now cut away at its junction with the stem, using a hot knife. Eleven days later there was 

 a distinct wilt of the leaves to either side of the pricked one. Three days later (August 8) the next 

 two leaves farther up were wilted. 



(362.) This plant was 22 inches high. The fifth leaf was inoculated 8.75 inches from the stem. 

 Its blade was 6 inches broad. The sixth day ( 10 a.m.) there was no trace of the wilt, but the following 

 noon there was wilt of about 10 sq. cm. of tissue in and around the pricked area. The wilt reached 

 nearly half-way down the blade. The leaf was now removed close to the stem with a hot knife. 

 Eight days later (15 days after inoculation), the blade of the first leaf up showed a decided droop. 

 The leaves below had shriveled from other causes. The twentieth day after inoculation several more- 

 leaves above the pricked one showed the bacterial wilt and three days later there were three addi- 

 tional wilted leaves, farther up the stem. 



(363.) This plant was 26 inches high. The sixth leaf was inoculated 10 inches from the stem. 

 The pricked leaf-blade was 6 inches broad. The first signs of wilt were visible the ninth day (2 p.m.) 

 and were confined to the pricked area. Two days later the pricked area was dead and the tissue 

 around it was yellow. There had been only a slight increase of wilt, but the whole leaf had a slightly 

 yellow look. The thirteenth day (4. p.m.) the wilted area measured about 20 to 25 sq. cm. and 

 extended along the midrib three-fourths of the way to the petiole. The leaf was now cut away close 

 to the stem with a hot knife. Seven days later there was a distinct wilt of several leaves above the 

 pricked one and 3 days after that additional leaves were wilted. 



(364.) This plant was 25 inches high. It was inoculated on the fifth leaf, 9.5 inches from the 

 stem. The pricked leaf-blade was 5.5 inches broad. The plant was healthy on the afternoon of 

 July 25. The eleventh day (10 a.m. July 27), the pricked area was dead and the surrounding tissue 

 freshly wilted. In all there were about 3 sq. cm. of wilt. Two days later (4 p.m.) the wilted area 

 around the pricks covered about 10 sq. cm. and was mostly dried out. The fifteenth day (2 p.m.) 

 the wilt reached two-thirds of the distance to the petiole and covered 20 sq. cm. The leaf was now 

 cut away with a hot knife close to the stem but 13 days later the blades of the first three leaves up 

 were drooping. On examining each of them microscopically I found bacilli in the vessels in the base 

 of the petioles. 



(365.) This plant was 22 inches high. It was inoculated on the fifth leaf 10.5 inches from the 

 stem. The pricked leaf-blade was 6.5 inches broad. The eighth day no signs had appeared, but the 

 following day (2 p.m.) there were about 2 sq. cm. of wilt in and around the pricks. During the next 

 3 days the wilted area increased to about 10 sq. cm. The leaf was now (July 28) cut away with a 

 hot knife at its junction with the stem. No secondary signs appeared until after August 8. On August 

 13(16 days after removal of the leaf) the blades of several leaves up were drooping. I examined their 

 petioles microscopically and found bacilli abundant in the vessels. 



(366.) This plant was 18.5 inches high. The fifth leaf was inoculated 9.5 inches from the stem. 

 The pricked leaf-blade was 6 inches broad. The fifth day at 1 p.m. there were no traces of the dis- 

 ease, but 2 hours later there was about 1 sq. cm. of wilt, mostly in the pricked area, but extending 

 out a little on one side. By the next morning the wilt had increased about 1 sq. em. and 26 hours 

 later (noon, July 23) measured about 14 sq. cm., reaching half-way to the base of the blade. With a 

 hot knife I now removed the leaf at its junction with the stem. The plant showed no constitutional 

 signs until after July 27. Eight days after the removal of the pricked leaf (July 31) the blades of the 

 first four leaves above were badly wilted. The first two below had dry-shriveled from other causes. 

 Five davs later five or six leaves above the pricked one had wilted and in 3 days more all the remain- 

 ing leaves had succumbed to the wilt, and the vine, which was now about 5 feet long, had begun to 

 shrivel. 



(367.) This plant was 18.5 inches high. The sixth leaf was inoculated 7.5 inches from the stem. 

 The leaf-blade was 6 inches broad. By the thirteenth day (4 p.m.) there were about 2 sq. cm. of 

 wilt extending along one side of the pricked area most of which was still sound. From this I inferred 

 that the infection resulted from a few bacteria lodged on one side of the pricked area. Two days 

 later (July 31, 2 p.m.) there were about 10 sq. cm. of wilt reaching more than half-way to the base 



