234 BACTERIA IN RELATION TO PLANT DISEASES. 



ings were made on July 23. The roots were broken considerably, and purposely, in trans- 

 planting both the tomato and Datura, and the tops were pruned back to correspond. 

 They soon recovered from the transplanting. The results were as follows : 



August j. Five of the tomato plants show wilt to-day. Brought in two for examination. These 

 are the smaller of the 5 and all their leaves have collapsed. No evidence above ground as to the cause 

 of the wilt. They were all right day before yesterday. Cut stems at surface of earth and also about 

 4 inches above. The vascular bundles in each plant are gorged with a gray-white slime. Examined 

 sections from each stem under the compound microscope the slime consists of myriads of bacteria 

 of the same morphology as those seen in the tobacco stems planted in the bed. The tomato plants 

 went into the bed July 23 ; they have, therefore, been exposed to the infection just 1 1 days. The 

 tomatoes came from out of doors on our grounds ; part from west of the grapery and part from the 

 north end of the grounds. There are no checks on these, but they were all sound plants when set 

 into this bed. On the Daturas there are hundreds of checks in the northern part of the city, in open 

 ground where they grew. All of the transplanted Daturas are still healthy. 



August 5. The weaker stramoniums between the rows of buried tobacco begin to wilt (old 

 rose house) ; brought in 4 and examined. No bacteria : A white mycelium occurs on the roots and a 

 Fusarium in the vessels (internal conidia) . This fungus was probably brought into the house with 

 the plants, some of which came from an old chip pile and rubbish heap. The bacteria have scarcely 

 had time to diffuse through the soil and affect these plants. Brought in 4 more wilted tomatoes. 

 The vascular bundles are browned and swarming with a short motile bacterium which is typical for 

 Bad. solanacearum. It occurs in great numbers. Inoculated 4 tobacco plants in the orange house 

 with juice squeezed from these 4 infected tomato stems; 4 places on each plant middle of two upper 

 leaves (midrib and parenchyma), on stem under an upper leaf and lower down on the scar of a leaf 

 torn off for this purpose; latter just rubbed in, rest by needle-pricks. Thorough. Plants 2.5 feet 

 tall. Not in bloom. 



August 7. Brought in one more wilted tomato plant. At 9 inches from the roots the vessels are 

 browned and full of typical bacteria. At level of the ground the inner tissues are worse affected, but 

 there is no external disease. At a foot from the ground the bacteria are also in the vessels, but the 

 brown stain is wanting. 



A ugust 10. Brought in from the bed in the old rose house 8 additional wilted tomato plants. 

 Cut each tomato stem cross-wise in several places. Bach is badly infected in the vascular system by 

 bacteria. There are millions of these. They are short rods with rounded ends, oozing out of the 

 browned vascular ring as a gray slime. Examined each plant microscopically. The infection in 

 most cases extended from the base of the stem upward a foot or more ; the only free vascular part is in 

 the extreme top of the plants. (Did not examine vascular system of leaves.) In one case I found the 

 gray bacterial ooze j inches in advance of the brown stain at the top of the plant. The others were 

 too much infected to show this difference. The outside of the plants was sound even at the surface of 

 the earth. Eighteen tomato plants have now gone down with this wilt. 



August 14. One of the stramoniums came down to-day with the tobacco wilt. Its vessels are 

 brown and swarming with short, motile, rod-shaped bacteria, which seem to have entered through 

 two broken roots. The bacteria are abundant enough to ooze from a cross-section of the stem 6 

 inches from the roots, as a gray slime. The organism was found in cross- sections of both the browned 

 roots (examined microscopically) and issuing as a gray ooze. Surface of roots sound; stem also 

 sound on its surface. Plenty of sound roots. 



August 1 6. Brought in another wilted Datura from the bed which had diseased tobacco planted 

 in it. On dissection the vascular bundles were full of the gray bacillus. Third case. 



August 77. One additional tomato wilted. It is sound externally and is 55 cm. high. All the 

 foliage is green and freshly wilted , and there is no external indication as to the cause of the trouble. 

 Bacterium solanacearum is present in the vessels of the stem all the way from its base to the top of the 

 plant. The vessels are browned below but not in the top of the stem. Bacteria most abundant 

 below, where on cutting the stem they ooze as a gray -white slime ; entrance apparently through one 

 small wounded root. This contains the bacteria; the others look sound. Bacteria are present in 

 the midribs of all the leaves at their junction with the stem and in all but the top ones half-way out 

 or more. Two top leaves required the use of the microscope to show the presence of bacteria in the 

 vessels, i. e., no ooze was visible. 



August 26. Pulled, brought in, examined microscopically, and had photographs made, of 

 the 4 tobacco plants inoculated August 5, with slime from the stems of tomato plants which were 

 infected through broken roots by planting over the buried tobacco in the bed in the old rose house. 

 Best parts put into Carnoy. Vascular system of plants fully diseased from top to base, especially 

 on one side where there are black stripes on the stems. It is the Granville wilt in typical form (pi. 42). 



