FRUIT-GROWING IN THE UNITED STATES 453 



the danger of injury from sunscald. The two extremes are I foot 

 and 2 1 feet, the latter being the most common height for apple 

 trees. The tops of the inland trees are kept much thicker than 

 those in the Coast Region and in the Atlantic States. A very 

 diffuse and spreading habit of growth is desired from the beginning. 

 Every effort is made to keep the trees close to the ground and to 

 shade the trunks. The greater difficulty in tilling orchards of such 

 low-headed trees is considered not at all commensurate with the 

 advantages gained in free- 

 dom from sunscald, in the 

 lessened danger of injury 

 from high winds, and in 

 the increased facility of 

 harvesting and spraying. 

 It is rare that one can find 

 within a few hundred miles 

 of each other such utterly 

 dissimilar methods of hor- 

 ticultural practice as are to 

 be seen in Northwestern 

 fruit-growing. 



3 . Coi 'cr crops. I n both 

 the Inland Uplands and 

 the Inland Valleys the 

 question of cover crops 

 for orchards is now attract- 

 ing attention. Almost all 

 the orchard soils in both 



regions are deficient in humus, and constant clean tillage during the 

 hot, dry summers tends to burn out of the soils what little humus 

 they have naturally. In the Inland Valley orchards the cover-crop 

 problem is not so difficult as in the upland orchards, because mois- 

 ture for the germination of cover-crop seeds can be supplied at 

 any time by irrigation. On the uplands, however, practically no 

 rain falls between the first of July and the first of October. It is 

 absolutely essential that the orchard be tilled early in the season ; 

 therefore no cover crop can be sown over all the ground in spring. 

 When tillage has ceased in late July or August the soil is so dry 



Fig. 192. Ingram apples in the Ozarks 



