1 86 



BACTERIA IN RELATION TO PLANT DISEASES. 



July ig. Thirty-five inoculations were made into the following plants: Tomato (15 plants), cucumber (6 fruits), 



potato (6 plants), Solatium dulcamara (8 plants). The cucumbers and part of the tomatoes were in the open 



air, the rest in the hothouse (temperature 90 to 100 F.). The cultures used were 6 agar streaks from as 



many colonies on poured plate from the interior of a tomato plant inoculated earlier in the summer (see pre- 



ceding set). 

 Result. Successful on tomato and potato, the first signs appearing on the fourth day (in one potato on the third day). 



Only slight local signs in Solatium dulcamara. Negative on cucumber. (For appearance of cross-section of 



petiole of potato at end of the sixth day see fig. 95.) 

 November 5. The following plants were inoculated: Tobacco (6 plants, i foot high), tomato (6 plants), potato (6 



plants). Two leaves on each tobacco plant were inoculated by needle-pricks (20 to 30 pricks each). The 



plants were in the hothouse at 80 to 90 F. All were very healthy and growing well. Two potato cultures 



were used, one 7 days old or more and browning, the other 72 hours old and from the preceding, descended 



from agar- tube No. 13, July 18, from inoculated tomato. The first potato culture was inoculated from an 



old browned agar culture, which had been in the ice-box all summer. 

 Result. All failed. 

 June, 1902. Potato and various weeds (Abutilon, etc.) were inoculated by hypodermic injection from cultures obtained 



from diseased tomato received from Georgia (1902). Thiswas a large field experiment with various fertilizers. 

 Result. The disease was produced on the 



potato, but it appeared slowly 



and in comparatively few of the 



many inoculated plants. 

 June . A duplicate of the above ex- 



periment, except that the cul- 



tures used were obtained from 



a diseased tomato received from 



Porto Rico. 

 Result. As above. 

 July 9. Another duplicate of the experi- 



ments of June. Cultures used 



were from diseased tomato (?) 



from Maryland. 

 Result. As in June. 

 June 4, 1903. Six tomato plants were 



inoculated with cultures of June 



i (i to 3 potato, 4 to 6 slant 



agar), which were isolated from 



a tomato plant received from 



Texas, all from plate 17, May 



28, poured from interior of green 



and recently diseased petiole. 



The plants were rather far ad- 



vanced in disease when received 



and contained numerous in- 



truders. Six colonies were used. 



The slime was viscid and dis- 



tinctly yellow in some tubes. 

 Result. No wilt within 5 weeks. Hot- 



house experiment. Probably 



wrong organism isolated.* 

 July 6. One plant of Datura stramonium 



was inoculated by means of forty 



needle-pricks in leaf-blade, using slant agar-tube No. i, July 2 (descended from tomato from South Carolina). 

 Result. No record. Probably failed. 

 July 7. Tomato (6 plants), Datura stramonium (2 plants), Datura fastuosa (i plant). Datura cornucopiae (i plant), 



were inoculated from agar-slant tubes Nos. i, 3, 4, July 2, from potato cultures which had become black 



(descended from tomato stems from Spartanburg, South Carolina). The agar- tubes were the second sub- 



cultures from poured-plate colonies. 

 Result. Everyone of the ten plants contracted the disease. One tomato plant (No. 7) was perfectly healthy in appear- 



ance July 2 1 , but succumbed August 3. For appearance of plant No. 10 at end of 7 days see fig. 96. 

 July 7. Tomato (4 plants), Datura metalloides (i plant), were inoculated by needle-pricks (12 into each stem), using 



tubes Nos. 3 and 4, July 10 (from potato stem, Norfolk, Virginia). 

 Result. All became diseased. For result on Datura see vol. i, plate 4. 

 July 16. Tomato plant No. 17 was inoculated from slant agar No. I, July 13, the third subculture from a colony 



from tomato (South Carolina). The plant divided into two equal branches. 

 Result. Successful. The first signs of infection were visible on the third day. Several leaves wilted on July 21. 



Numerous adventitious roots pushed out along stem in the two inoculated internodes, while the surface of 



the check-internodes was perfectly smooth. Roots were also pushing out of the two internodes below the 



lowest point of inoculation. Several photographs were made of this plant at different stages (consult plates 



26 and 27). 



*I now suspect this Texan disease may have been due to A planobacter michiganense (see page 161). 



fFlc. 94. Radial longitudinal section through xylem part of the stem of Physalis Philadelphia, showing Bacte- 

 rium solanacearum confined to the spiral vessels. The pith is toward the left. The pitted vessel x lies not between the 

 spirals but just below them. This section was made from the same piece of stem as fig. 93, i. e., the plant was No. 57 

 inoculated August 17, 1896, by needle-pricks on the upper part. The material used for this section was taken on Sep- 

 tember 23 about 6 inches below the pricked part. The plant was infected with a pure culture derived from an egg- 

 plant. Drawn from slide 120(3. 



. 

 ! 



