132 THE POTATO 



3. The transpiration' of moisture is greater in 



sprayed plants. Food is moved from the roots 

 to the leaves in water, the food is worked over, 

 and the water is given off. The more food- 

 laden moisture passing through, the greater is 

 the growth. 



4. The assimilation ' or taking in of food from the 



air by the leaves is much greater. 



5. The duration* of the leaves and vines ^ is greater. 



6. The growing period' is extended (Fig. 41), insur- 



ing a heavier yield. In Vermont blight often 

 appears in August, and from then on the pota- 

 toes have grown 50 bushels a week when the 

 foliage was preserved. 



7. The tuber produdlion' is increased, due to increase 



in the size of the tubers* and the number of 

 tubers per plant. Jones & Morse, ^ of Vermont, 

 show that the average j'ield for thirteen j^ears 

 (189 1 to 1904), without spraying, was 171 

 bushels per acre, while the sprayed plats yielded 

 286 bushels per acre, or an average annual gain 

 of 115 bushels per acre. 



8. The dry matter' is increased. 



9. Starch formation' in the tuber is considerably in- 



creased. At Geneva, (N. Y.) Experiment Sta- 

 tion' an increase of 7 per cent, was obtained. 

 ID. Where there is no disease' the yield may be in- 



> Frank & KrUger. E S. R., VI., p. 306 ' Vt. Report, 1S99. p. 156. 



' vt. Bui. 40, pp. 26, 27 ; Report, 1S99, p. 272. Can. Exp. Farms Report, 



1901, p. 120. 

 « (N. Y.) Geneva Bui. 221. » Vt. Bui. 106, p. 231. 



• (N. Y.) Geneva Bui. 221. 

 » E. S. R., Vol. LX., p. 765. (N. Y.) Geneva Bui. 123, p. 234. 



