EXPERIMENTS WITH THE PEACH OEGANISM. 73 



PEACH ON PEONIA. 



Inoculations of May 6, 1909 (Smith and Brown). 



Four roots of Peonia officinalis were inoculated with peach gall 

 organism — culture 2 days old (isolation of 1908). Leaf buds were 

 just starting out of the root stocks, and inoculations were made at 

 the base of these, also on the roots themselves. Three checks were 

 held. 



Result. — September 2, 1909: The plants were knocked out of the 

 pots and examined carefully. No galls were found in those inocu- 

 lated. We were led to make these inoculations because Dr. WhetzeJ 

 reported finding root-galls on peonia in New York. 



PEACH ON SUGAR BEET. 

 Inoculations op March 11, 1908 (Smith). 



Five sugar beets were inoculated by needle pricks on the crown 

 with an agar subculture of an organism isolated from a crown-gall 

 on peach and previously passed twice though the peach with the pro- 

 duction of tumors. 



Result. — May 4, 1908: Each one of the 5 plants contracted the dis- 

 ease at the point of inoculation and not elsewhere (PI. VI, fig. 2). 



PEACH ON HOP. 



Inoculations op June 10, 1908 (Brown). 



Six young hop plants from seed grown in sterile soil in pots in the 

 greenhouse were inoculated by needle pricks at the crown with agar 

 streak cultures 4 days old. Two plants kept as checks were punctured 

 in the same way at the cro\vn. 



Result. — June 30, 1908: 100 per cent of infections. Kjiots three- 

 fourths inch to an inch in diameter had developed on each one of the 

 6 inoculated plants. These knots were white and grew more quickl}^ 

 than those on the peach. The checks remained free. 



PEACH ON RED OAK. 



Inoculations of May 20, 1908 (Brown). 



Young seedling red oak trees about G inches tall were inoculated 

 on the cro\vn and on the stem with agar streak cultures 2 days old. 

 Eleven trees we re inoculated ; 4 were held as checlvs. 



Result. — September 2, 1908: The trees had not made any note- 

 worthy growth, but a small knot or knobby outgrowth was present 

 on one of the inoculated stems. The checks remained free. 



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