44 CROWN-GALL OF PLANTS. 



DAISY ON VARIOUS ORCHARD TREES. 



Inoculations of April 13, 1907 (Smith and Brown). 



The following varieties were used, each receiving 30 pricks in groups 

 of 5 : Windsor pear, Sheldon pear, Bartlett pear, Worden Seckle pear, 

 Wickson plum. Abundance plum, Montmorency cherry, Black Tar- 

 tarian cherry, Harris apricot, J. L. Budd apricot, soft-shell almond, 

 and American chestnut. 



The trees were for the most part overgrown and in bad condition 

 when received from the nursery, but bore no root knots or cro%vn- 

 galls. They were brought to the laboratory, the roots scrubbed, and 

 then inoculated with young agar streak cultures; 2 of each sort were 

 inoculated and 2 were held as checks. 



Result. — June 10, 1907: The almond trees died without leafing out. 

 When pulled up and examined to-day no tumors were found on the 

 roots. Most of the chestnut trees were also dead and dying. They 

 leafed out a little bit, but not to any great extent. No tumors were 

 found on the roots. The two trees of Black Tartarian cherry were 

 also pulled up and examined. There were no tumors on the roots. 

 They had leafed out a very little and then died. 



July 13, 1907: The remainder of the trees were dug and examined 

 for galls. Condition of the roots as follows: 



Worden Seckle pear — No. 363, small root tumor and several badly 

 overgrown calluses, which are like tumors; No. 364, overgrown cal- 

 luses. 



Sheldon pear — No. 397, small tumors scattered along root; No. 398, 

 badly overgrown calluses. 



Bartlett pear — No. 379, small tumors along root and tumefied 

 calluses badly overgrown; No. 380 (which is smaller than the 

 others) bears on its roots 3 well-developed, typical root tumors. 

 The largest one is connected with the root by a small pedicel and is 

 over an inch in diameter. The Bartlett pear seems to be quite 

 susceptible. 



No tumors resulted from the inoculations on any other of the trees 

 used in this experiment, but the evidence is of little negative value 

 owing to the character of the trees at the time of inoculation. We did 

 not at this time understand the necessity of inoculating into growing 

 tissues. 



DAISY ON CABBAGE. 

 Inoculations of March 29, 1907 (Brown). 



Young cabbage plants were inoculated on the leaf blades with 

 4-day-old agar cultures isolated from the daisy. 



Result. — April 15, 1907: Knobbed growths developed at all the 

 places of inoculation. 



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