48 CKOWN-GAU. OF PLANTS. 



DAISY ON HOP. 

 Inoculations of April 8, 1907 (Smith and Brown). 



Two varieties of hop were usefl: The EngHsh Cluster and the 

 Custis Late. The plants were knocked out of the pots, brought to 

 the laboratory, and washed carefully. All were free from tumors. 

 They came fi'om New York. Eight of the English Cluster and 10 

 of the Custis Late were inoculated by means of needle pricks (20 to 

 40) on each fleshy root in groups of 5, with viscid agar streak cul- 

 tures 4 days old. Four checks of each variety were held, each receiv- 

 ing the same number of punctures as the inoculated plants. The 

 vines were then taken back to the hothouse and set in 10-inch pots. 



No checks were made into daisy plants (1) because none were con- 

 venient, and (2) because the 4 tubes used in this experiment are part 

 of the same lot used for inoculating peaches on April 6, and checks 

 were kept on 12 daisy plants at that time (p. 39). 



Result. — May 6, 1907: Knots were on the crowns of each of the 18 

 inoculated plants where punctured. The 8 checks were free. 



July 11, 1907: The vines have grown slowly. The results are as 

 follows : 



ENGLISH CLUSTER. 



No. 163: Four tumors on the roots, each one-half inch or more in diameter. 



No. 164: Two small tumors on the upper part of the root. 



No. 165: Two tumors on the upper part of root, each about as large as a wax bean; 

 one on one side of the root and the other on the opposite side, evidently corresponding 

 to the pricked places; midway between the two a small tumor is breaking through 

 the root. 



No. 166: One small tumor about as big as a pea. 



No. 167: A decaying tumor at the top of the root and a smaller sound one a few 

 inches down. 



No. 168: A tumor about \\ inches long on the upper part of the root; really a mul- 

 tiple tumor, two having fused. 



No. 169: Two tumors on the base of the stem; the larger is half an inch or more in 

 diameter and the other about half as large; none on the roots. 



No. 170: Three tumors on the upper part of the roots; 1 about an inch in diameter, 

 1 about half that size, and 1 quite small. The smallest is on a side root about \\ 

 inches below the largest one. 



CUSTIS LATE. 



No. 177: A tumor about an inch in diameter (longest way) at the top of the root; 4 

 smaller timiors scattered along the roots. The lowest one is at least a foot below the 

 crown, and the root that bears this bears two others. 



No. 178: This plant has made scarcely any growth, the two crown shoots being not 

 more than a few inches long with diminutive leaves. Two small root tumors, each 

 about as big as sweet-pea seeds. 



No. 179: Seven root tumors, the largest over a half inch in diameter, the others 

 about as big as small peas. Some are on the main root, some on the small side roots. 



No. 180: Four tumors; 3 about as large as beans and 1 small; 3 of the 4 are on the 

 stems near the roots; the smallest is on the root. 

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