508 



GROWING GRAPES 



turns will usually be secured, however, from the addition of 

 either or both of these materials. 



Factors such as good air drainage (freedom from frosts), 

 soil drainage, proper pruning, thorough cultivation, the addi- 

 tion of organic matter, the control of insects and diseases, soil 

 temperature and aeration, and winter injury exert a marked 

 influence upon vine growth and fruit production. If proper 

 attention has been given to all these factors, and the vineyard 

 still makes an unsatisfactory growi:h with resultant low fruit 

 production, fertilizers should be added. 



In many vineyards nitrogen seems to be the fertilizing ele- 

 ment most often needed. A review of experiment station 

 recommendations and of experimental evidence shows that in 

 the Northern states, if satisfactory growth and yields are not 

 secured, although good vineyard management is practiced, 

 then applications of nitrogenous fertilizers will usually be 

 beneficial. 



In such cases, annual applications of 5 to 10 tons of barn- 

 yard manure per acre should produce good results. If manure 

 is not available, about 300 pounds per acre of nitrate of soda 

 should also produce good results, but under conditions where 

 vine growth is very weak it will often pay to apply 400 to 500 

 pounds of nitrate of soda per acre. 



In the lighter soils of the South and in some of the northern 

 vineyards, a profitable response is apparently secured by ap- 

 plying phosphoric acid and potash as well as nitrogen. Under 

 such conditions applications of 800 to 1000 pounds of acid 

 phosphate and 200 to 300 pounds of muriate of potash in addi- 

 tion to the nitrogen should be made. It is possible, however, 

 that too frequent and too liberal applications of manure and 

 nitrogenous fertilizers might cause an excessive w^ood growth 

 and diminish the crop. The amount of growth and yields 

 being secured should thus be considered in deciding on the 

 fertilizer program. 



When manure is to be applied to the vineyard, it should 

 be spread evenly between the rows before plowing or disking 



