250 HORTICULTUKAL MANUAL. 



nitrate of soda, potash, and phosphoric acid as the vine- 

 yard attains age. 



239. Shading Vineyard Soils, It is stated above that 

 cover-crops cannot be used in vineyards. This is true in 

 practice, as the shading of the soil by growing crops is in 

 the way of needed summer care and it favors rot and other 

 fungoid diseases. It is also true that the general belief in 

 all parts of the Union is, and has been, that the bare, 

 well-tilled soil is needed by the heat-loving grape-vine. 

 But facts do not warrant the latter belief. In Nature the 

 American wild species grow to greater perfection where 

 the roots are shaded by tree- and plant-growth and by the 

 leaves and leaf -mould. That at least some of our best 

 varieties need shade of roots from the sun in the heated 

 period is shown by the fact that the Delaware, with bare 

 surface culture, is a failure in Iowa. But when the space 

 between the rows is quite deeply covered with sorghum 

 bagasse or prairie hay, it shows healthy foliage and bears 

 full crops of as perfect fruit as is grown, where it is a 

 favorite commercial variety. In the perhaps distant 

 future it no doubt will be found advantageous to cultivate 

 early in the season, and when the time for mildew and 

 black rot comes have the bare soil covered with some low- 

 growing leguminous growth, such as burr clover or our 

 small-growing vetches. 



