BROWN ROT OF SOLAN ACEAE. 



189 



June 27, 1905. Potato plants (2 varieties) were inoculated from tubes Nos. 4, 5, 6, June 22, from as many colonies 



(stem of tomato, Hastings, Florida). Made 85 inoculations on shoots and leaves on 26 plants. 

 Result. Positive in part; slow. On July 13 the Blush showed fewer cases than the Early Rose. Plants on this date 2 



to 2.5 feet high. 

 The difference in resistance appeared to be lodged in particular plants. The Blush was more resistant than Early 



Rose. Each culture was virulent. (See vol. I, plate 24. The source of the culture is there stated to be 



potato, but the potato organism from Hastings appears to have been tried only on tobacco except as below, 



unless certain of the notes have been lost.) 

 July S. Eight tobacco plants were inoculated in stem and leaf with potato-cultures A and B.July 6 (from two separate 



colonies, descended from potato tuber, Hastings, Florida). 

 Result. Failure. The experiment was followed until September 6, when 6 plants were examined microscopically. 



Bacterial multiplication and brown stain slight and confined to pricked parts. 

 July S. Thirty-four young tomato plants 12 to 16 inches high were used in this experiment (variety test). Potato 



cultures A and B, July 6 (from 2 separate colonies descended from potato tuber, Hastings, Florida), were used. 



Fig. 97.* 



Result.- Most of the plants grew to be 6 to 9 feet long, fruited well, and were alive 4 months after the inoculations. 

 They doubled in size within 6 days after the inoculations, and the inoculated shoots had elongated about 12 

 inches. The plants continued to grow rapidly. On July 25 they were 3 times as large as on July 8. A few 

 cases developed very slowly, most failed, except that the inoculated parts were swollen and browned and 

 adventive roots pushed out. Of many varieties, Livingston's Dwarf Aristocrat was most susceptible In 

 October a plant with large pear-shaped fruits contracted the disease and the bacteria were found filling vessels 

 of stem and branches 4 feet from the needle-pricks. 



September 23. Tobacco (24 large plants) was used for this experiment. The plants were inoculated by needle-pricks 

 in the stem, introducing potato-cultures A to D, September 21 (potato tuber, Hastings, Florida.). 



Result. Slow progress of disease; pith blackened. No distinct wilt. 



September 23. Tomato plants were inoculated with potato cultures A to D, September 21 (potato tuber, Hastings, 

 Florida). 



Result. Adventive roots developed and some shoots were swollen and stunted; wilt developed not at all or very slowly. 



September 30. Tomatoes (20 plants, 10 to 12 inches high) were inoculated by needle-pricks with beef-bouillon cultures 

 A to D, September 20 (potato tuber from Hastings, Florida). 



Result. Failure. 



*Fig. 97. Tomato plants pricked with a delicate needle at X, X on July 5, 1904. When used on the left-hand 

 plant the needle was sterile, when used on the other (No. 64) it was flamed and then dipped into a 3-day-old culture of 

 Bacterium solanacearum (District of Columbia strain). Photographed July S. 



