274 Report of the Department of Botany of the 



of such drops were collected in, a clean atomizer and inoculated with 

 the spores of the Fusicoccum stage of the fungus (2971) from culture. 

 These spores were sprayed on a large number of shoots of Concord 

 vines. Clinging drops of water were then examined and an abundance 

 of spores found. Contemporaneous germination tests on glass slides 

 showed the spores to be viable. No lesions developed on any of the 

 shoots, although the tips were relatively tender. 



inoculation with the saw. 



First series. — In order to determine the effect on the vines as 

 well as to serve as a check on the experiments about to be described, 

 the trunks of six Worden grapes, eighteen years old, were cut half 

 off with a saw, the cut being made near the ground. Twenty-eight 

 other vines in the same row were treated in a similar manner except 

 that the cuts were not all so deep and that in each case the saw was 

 drawn a few times through a diseased stem and then through the 

 cut previously made. In some cases the saw cuts were made near 

 the arms or in the arms. The object of the experiment was to deter- 

 mine if possible what number of infections occur in this manner. 

 All cuts and inoculations were made July 7, 1909. The infected 

 wood used as a source of inoculation was taken from a vineyard 

 at Prospect, N. Y., the previous day, and by examination with the 

 microscope was known to be infected with the dead-arm fungus. 



An examination was made on July 1, 1910, and notes taken on 

 each vine. The vines used as check showed no ill effects of the 

 treatment. The wood was found somewhat discolored for a short 

 distance each way from the cut, in the vine examined, but otherwise 

 seemed to be perfectly sound. 



The remaining twenty-eight vines, without exception, showed an 

 exudation of gum about the cut. There was no apparent effect on 

 the vines but three or four were examined and it was found that a 

 dead area extended in each direction a distance of one or two inches. 



A second examination was made June 27, 1911. No healing of 

 the wounds had occurred on the check vines. They showed no 

 apparent effect of the treatment and none of them showed gum 

 flow. Many of the inoculated vines still showed gum flow. In a 

 number of cases a sunken pit an inch or more in diameter appeared 

 about the cut. In one vine examined, the wood about the cut was 

 found to be blackened and dead a distance of three inches each way 



