432 Bulletin 76. 



weeks all growth had stopped. Examination of the plant failed 

 to show any starch except traces in the green portion. When 

 potash salts were added the plants began to grow again and starch 

 was formed. 



The development of sugar in fruits is dependent upon the 

 presence of starch, for in the plant this substance is changed into 

 the sugars, which sweeten the fruits. Some experiments have 

 been made which have particular bearing upon this point. Dr. 

 Stone, of the Massachusetts Agricultural College* makes the fol- 

 lowing statements : "A wild specimen of Vitis L,abrusca (our 

 common wild grape) was torn apart at its root ; one half was left 

 in its natural condition, the other transplanted to cultivated 

 ground and treated with nitrate of potash and bone superphos- 

 phate. At the end of three years fruit from the cultivated vine 

 contained twelve per cent, more potash and twenty per cent, more 

 sugar than that from the wild one." Dr. Stone declared also that 

 " potash fertilizers have decidedly improved the desirable quali- 

 ties of our fruits. Wherever the percentage of this element has 

 been raised the change is accompanied by an increase of sugar 

 and decrease of acid." Other examples might be given, but these 

 will answer for the present purpose. 



All grape growers are agreed that the flavor of shelled grapes 

 is none of the best ; in fact such grapes are very insipid. Although 

 this does not necessarily prove a lack of potash, the probabilities 

 are that such is the case. All other causes which might produce 

 such a result have been almost entirely excluded, so that we are 

 apparently forced to accept this as the true cause of the difficulty. 

 By a lack of potash is not meant necessarily that the soil is defi- 

 cient in this element, but rather that it is not found in a form 

 which makes it available as plant food. 



The reasons for this want of potash are not very difficult to find. 

 The lands upon which the majority of the Chautauqua vineyards 

 are now growing had been used for many years for the production 

 of grain and hay. Almost no fertilizers had been returned to the 

 soil and the natural consequences followed. The supply of avail- 

 able plant food in the soil has become more or less exhausted. 



*Amer. Gard. vi. 210 (1885), cited by Bailey, Agricultural Science, vi. 

 No. II. 1892, p. 5C0. 



