THE CUBE OF CROWN-GALL. 25 



forming in injuries to vines caused by late frosts at Bernalillo, 

 N. Mex. They were also noted forming in wounds received by 

 cultivation and in those due to pruning. The pruning knife appar- 

 ently may disseminate the organism. 



In a vineyard under the observation of the writer at Bernalillo, a 

 virgin piece of soil was leveled and planted with Mission vines of the 

 New Mexico variety. These were placed on a terrace slightly lower 

 than an older vineyard containing the badly diseased vines of an 

 earlier planting. The new vineyard was planted with healthy vines 

 grown from cuttings taken from healthy vines. The vines grew well 

 and all remained healthy for a year. Then a careless workman who 

 was irrigating by surface irrigation allowed the water to break 

 through a ridge and flow directly from the old vineyard across the 

 center of the new one. The following year the vines in the over- 

 flowed portion of the new vineyard became diseased. The fourth 

 year the disease had spread by irrigation to all portions of the vine- 

 yard. 



In central California it was noted that vineyards that were sub- 

 irrigated showed little crown-gall, but those of the same varieties in 

 adjacent vineyards that were surface-irrigated showed much of the 

 disease in all portions of the vineyards. 



Bees probably communicate the disease as carriers of bacteria 

 found in the galls and the adjacent diseased tissues. In the spring 

 they were observed feeding on the exuding sap after the vines were 

 pruned and then passing from diseased vines to healthy ones. 



That the disease can be communicated by means of diseased 

 cuttings has already been shown by the results of the experiment 

 previously described in this bulletin. 



THE CURE OF CROWN-GALL. 



NEGATIVE RESULTS FROM EXPERIMENTS WITH FUNGICIDES. 



As stated on a previous pagp, the experimental plat at Bernalillo, 

 N. Mex., originally was planted with about 5 acres of grapevines of 

 the Mission (California) variety, and these became badly diseased. 

 All the diseased vines were treated as follows in the spring of 1903 

 to control the disease: The ground was removed from the base of 

 the vines and all the galls cut away; then the wound was covered 

 with a paste made of copper sulphate and lime. 



Some of the vines were probably killed by this treatment, but the 

 disease was not checked, as galls broke forth anew from the vines on 

 other portions of the plants. 



The following autumn a portion of the vineyard was again treated 

 as follows: The vineyard was divided into blocks of five rows of 60 

 vines each. On three adjacent rows of vines about equally diseased 



183 



