566 REpoRT oF THE HORTICULTURIST OF THE 
investigations go to show that the chief damage to the crop 
arises’ from the action of the fungus to which Dr. Thaxter has 
given the name Odspora scalies. It appears that Dr. Thaxter’s 
work** in 1891, showing that this parasitic fungus causes potato 
scab, was confirmed both by his later investigations and by those 
of Prof. Bolley, and the theories that the scab is primarily due 
to injuries resulting either from insect depredations, or from 
excess of water in the soil, or from mechanical irritation, or from 
chemical action, or from the action of manure or other fertilizers, 
must be abandoned and it must be conceded that these supposed 
‘causes influence the prevalence of the disease only in so far as 
they may furnish more favorable conditions for the growth or dis: 
tribution of the fungus which really causes the scab. Figure 1)* 
illustrates in a very interesting way the results of one of Dr. 
Thaxter’s inoculation experiments. From a pure culture the 
fungus was applied to the surface of this tuber in lines so as to 
| form the monogram R. T., and so successful was the inoculation 
that the seab formed a nearly perfect monogram. Figure 11 
‘illustrates a potato badly scabbed by the action of the eee 
| 0 ispora: Scabies, Thax. 
DETAILS OF EXPERIMENTS. 
As previously stated two kinds of soil were selected for the 
experiments with potato scab during the past season namely, at 
Peruville, soil so thoroughly infected with the scab fungus that 
whenever planted with potatoes it invariably produced a crop 
that was mostly so scabby as to 'be unmerchantable; and at the 
Station, soil that was not known to be infected with the scab 
fungus. Scabby seed was selected for planting in both places 
and alternate rows were always left untreated for the sake of 
comparison. In making up the following tables each treated row 
was compared with the untreated rows on either side of it except 
in one or two instances where but one untreated row could be 
used for this purpose. 


** 1891, Annual Report Conn, Expt. Station, p. 159. 
* Figures 10 and 11 are from Annual Report Conn, Expt. Station;for 1890. 
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