89 



smooth tubers may still bear the germs ot the disease it they have come 

 in contact with scabby ones or have been put in bags, bins, etc., wh^re 

 scabby potatoes have previously been placed. (5) That the only way 

 to insure a smooth crop is to avoid planting the potatoes on land which 

 hat been previously contaminated, to avoid the introduction of the germs 

 on the manures and implements used, and to treat the tubers before 

 planting in such a way as to kill any germs already upon them. (6) That 

 if the germs are pres<^nt in the soil, or are introdnced on the tubers, 

 the character ot the soil and the nature of the manures; (even if 

 the latter are free from the germs) may under certain conditions exert a 

 decided influence on the development of the scab. (7) That no practi- 

 cal means has yet been devised tor destroying the germs of the disease in 

 soils already infested with them. (8) That of all the methods of treat- 

 ment: of the seed tubers and soil none of them seem to give fully satis- 

 factory results in case the soil is already badly contaminated with the 

 germs. (9) That treatment of the seed tubers with bichloride of mer- 

 cury is a very effectual means of lessening the scab if uncontaminated 

 soil is employed, and if all other means of contamination are avoided. 

 (10) That on soils which are acid, if lime and ashes are employed in 

 such a quantity as to make the soil practically neutral or but slightly 

 acid, there is probably danger of increasing the scab, provided the soily 

 seed tubers, or manures are contaminated with ihe germs of the disease. 

 If the soil and manure are free from the germs, and the tubers can first 

 be effectually treated, then liming can probably be resorted to without 

 hesitation. (11) That an acid condition of the soil is unfavourable to 

 the growth of the potato and probably to the fungus which produces the 

 scab, and that it is desirable to know with certainty how to avoid the dis- 

 ease and at the same time to increase, by liming, the yield of merchan- 

 table tubers. 12. That if potatoes are scabby they should be dug early. 



The best method of treatment now known for the destruction of the 

 germs of the fungus of the potato scab seems to be the corrosive subli- 

 mate treatment employed by Bolley ^ and others. ^ 



Treatment. Coirosive sublimate can be bought at drug stores in 

 the form of crystals. Two and one-fourth ounces of these crystals 

 should be dissolved in a few gallons of hot water and enough cold water 

 added to make fifteen gallons of solution; the whole should then be well 

 stirred. In preparing the solution, and treating the seed use wooden 

 vessels only. Two barrels with wooden faucets are convenient, the solu- 

 tion being drawn from one to the other whenever it is desired to remove 

 the potatoes. The potatoes may also be put in a sack and dipped into 

 the solution. The same solution may be used repeatedly. The whole 

 tubers after first being washed should be placed in the solution for one 

 and a half hours, then spread out to d ry, and cut and planted as usual. 



Various methods of treatment of the seed tubers for the accom" 

 plishment of the above mentioned object have been resorted to by vari- 

 ous experimenters, but the treatment proposed by Bolley, viz: that with 



1. Bulletins 4 and 9 of the N. Dak. Agr'l. Exp't Station. 



2. Kinney, 5th An. Rpt. R. I. Exp't Station, pp. 211-212. New York 

 Agr'l Exp't Station, Geneva, Bui. No. 49, New Series. T.B.Terry, Our 

 Farming, 1893, p. 206. 



