72 CROWN-GALL OP PLANTS. 



May 22. Twelve similar plants were inoculated on the crown only 

 with agar streak cultures 2 days old. 



Results. — June 12, 1908: Plants inoculated May 19: All the inocu- 

 lated places had galls except 1 . The exception was 1 of the 4 plants 

 inoculated only on the crown. 



All plants inoculated May 21 had knots on both root and stem, 

 except 1 plant which had a knot on the stem only. 



All plants inoculated May 22 had laiots. 



Total number of inoculated plants 34, of which 33 bore galls. In 

 most cases there were several groups of punctures on the stem, each 

 of which yielded a gall. 



The 4 check plants remained free from galls. 



April, 1909: The above galls rotted away and in 8 or 10 instances 

 new galls developed from their margins. 



PEACH ON ROSE. 



Inoculations of January 15, 1908 (Brown). 



Six rose bushes (variety Killarney) were inoculated at the crown 

 by needle pricks from 1 -day-old agar streak cultures, second subcul- 

 tures from the poured-plate colonies. The plants used were in pots 

 in the greenhouse. The soil was laid back carefully, and, after punc- 

 turing, the inoculated places were covered with moist cotton. 



Result. — April 17, 1908: A gall one-third inch in diameter on one 

 plant. (PI. II, fig. 1 . ) No trace of an enlargement on any other. The 

 plants were not growing rapidly. 



Inoculations of June 27, 1910 (Smith and Brown). 



Twelve shoots of rooted cuttings of as many rose plants (variety, 

 Killarney) were inoculated by needle pricks from agar streak cultures 

 3 days old, puncturing into the softest wood. 



Result. — October 21, 1910: All negative. The plants grew slowly. 

 The organism had probably lost virulence. 



PEACH ON MAGNOLIA. 



Inoculations op June 24, 1910 (Smith). 



The terminal part of 4 young rapidly growing shoots of a broad- 

 leaved magnolia {M. acuminata?) were inoculated by needle pricks 

 from a 2-day-old agar streak culture of the crown-gall organism iso- 

 lated (February 29, 1908) from the peach. 



Result. — July 30, 1910: Negative; suspect that organism has lost 

 its virulence. 



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