EXPERIMENTS WITH THE EOSE ORGANISM. 77 



Inoculations op May 9, 1909 (Smith and Brown). 



Twenty-five peach trees dug up and brought over from the Arhng- 

 ton Experimental Farm May 8 were inoculated and planted out. 

 The trees were rather leafy, and through an oversight the young 

 foliage was not removed from them until 10 a. m. May 9, so they 

 suffered consiilerably from transpiration. Ten of these trees were 

 pricked with a sterile needle for checks, 15 or 20 pricks each in 

 groups of 5, and the 15 remaining were inoculated with 1 -day-old 

 and 3-day-old agar streak cultures of the rose organism, which had 

 been on culture media since the fall of 1908. The inoculations were 

 made by means of needle pricks in groups on both sides of the main 

 root in the yellow bark. After the punctures were made the plants 

 were set out in 10-inch pots. Ordinarily the plants would not have 

 been watered immediately after inoculation, but they had suffered 

 so much from loss of water overnight that directions were given the 

 gardener to water them carefully as soon as he had finished potting 

 them. 



Result. — September 3: Shook trees from pots, washed and exam- 

 ined roots; no galls on inoculated or check plants; 5 inoculated 

 trees and 5 check trees were dead. 



These trees were set back in their development by stripping the 

 leaves in May, but this is scarcely sufficient to account for the non- 

 infection. The rose-gall organism does not cross-inoculate readily. 



ROSE ON APPLE. 

 Inoculations op January 23, 1908 (Brown). 



Six apple trees were inoculated with agar streak cultures 2 days 

 old. Punctures were made at 3 different places on each tree — at the 

 crown, above the crown on the stem, and near the end of the shoot. 

 Four controls were held. The variety of apple used was the Wealthy. 

 The trees were dormant. 



Result. — June 2, 1908: The trees were taken out of the pots, 

 washed, and examined carefully. No knots were found. Here again 

 possibly the dormant condition interfered with the infection. 



ROSE ON SUGAR BEET. 



Inoculations of December 3, 1908 (Brown). 



Seven small sugar beets were inoculated by needle pricks just 

 below the surface of the soil with agar streak cultures 7 days old. 

 Three checks were made. The house was cold, and the plants were 

 making a slow growth. When pulled up they were scarcely larger 

 than when inoculated. 



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