
564 _ Report or THE HorrTiovLTURIST OF THE Oitan 
(4.) The relation of soil conditions to the development of potato — 
scab received considerable attention before the real cause of the 
trouble was known. In Beckwith’s experiments at this Station 
excessive moisture favored the development of the disease* and ae 
Humphrey §-states that light, open, thoroughly drained soil seems 
to be less favorable to the development of the disease than does 
heavy, damp soil. But, in the bulletin referred to, Bolley well 
says, “There is no substantiated evidence that any soil of whatso- | 
ever kind can in itself give origin to the disease. That certain 
characters in a soil may increase the capabilities of the disease 
to work damage is possible. This point, however, is not proved, 
and even if it were, it need not militate against the use of any 
particular kind of soil if care is taken to avoid the first cause, 
the plant parasite. The same argument holds for the use of 
manures, though it is possible that barnyard manures may become 
contaminated from refuse matter containing the disease and thus 
become a source of infection. 
(5.) If the presence of scab is suspected, ah the potatoes as 
soon as they are matured.** 
- MANNER OF APPLYING THE FUNGICIDE. DIR a 
Regarding the question whether spraying the seed and the : 
surrounding soil at planting time is as effective in preventing ‘ ; 
scab as simply soaking the seed before planting, our investiga- 
tions indicate that under the conditions of these experiments 
the former method was more successful than the latter, but the 
treatment is somewhat more laborious and takes more material. B 
This opinion is based chiefly on the results of the experiments at 
the Station since on the Peruville soil the treatments had com- 
paratively little effect. When the first method was used the 
- freshly opened furrow or hill was sprayed with the fungicide, then 
after the seed was dropped it also was sprayed and then covered. 
When the latter method was followed the seed was soaked inthe  —_— 
fungicide one and a half hours and then planted. By 


* Annual Report for 1887, p. 311. 
§ Annual Report Mass. State Expt. Station for 1890, p. 220. : it 
** Thaxter states that scab spots deepen as long as the tubers remain in the ground. See 
Annual Report Conn, Expt. Station for 1891, p. 159. . eA 37 

