HORTICULTURE 275 



Cover Crops. Cover crops, if judiciously used, may be a very 

 decided benefit to citrus orchards. In fact, they will, in a long 

 term of years, be found necessary to maintain the fertility of the 

 soil. Constant, clean culture would in time exhaust the soil of its 

 supply of humus and render it unable to retain adequate moisture. 

 Humus is also a source of nitrogen supply, and when leguminous 

 plants are used as cover crops very considerable amounts of this 

 most expensive of commercial plant foods are added to the soil. 



In the use of cover crops, however, good judgment must be 

 exercised. It will not do, for example, to plant such crops in a 

 citrus orchard at the beginning of the dry season, unless abundant 

 water for irrigation be available, since they make large demands 

 for moisture. If planted at the beginning of the wet season, there is 

 likely to be enough moisture to supply both trees and legumes, and 

 the latter may be plowed under before the approach of dry weather. 

 It has been very reasonably suggested by some that in a tropical 

 climate it may be better to cut a cover crop and allow it to dry and 

 partly rot before plowing it under, there being thus less danger of 

 producing acidity in the soil. The best plants to use for this pur- 

 pose must be determined by experiment in each locality. 



Orange and other citrus trees, except the lemon, require little 

 pruning after the head has been properly formed. It is of great 

 importance that the tree be given a proper shape by judicious prun- 

 ing and pinching during the first years of its orchard life. The 

 aim should be to secure a low-headed, symmetrical tree, of upright 

 growth, covered with a compact, but not crowded, wall of foliage. 

 To secure this shape, begin when the tree is first set out. Its main 

 stem or leader should then be cut back to within about 2 1 /2 or 3 feet 

 of the ground. The laterals may be treated in either of two ways. 

 They may be allowed to start and grow as low as 1 foot from the 

 ground, with a view to gradually removing them later up to a height 

 of 2 feet, after these lower ones have borne the first fruit, or from the 

 start all branches below 20 inches or 2 feet may be suppressed. If 

 the tree grows very rapidly it will often be necessary to pinch back 

 the new growth to prevent the drooping habit, which is acquired by 

 the young shoots becoming too long and heavy to support their 

 own weight before woody tissue has been formed. During this 

 formative period, and in fact throughout the life of the tree, any 

 ambitious branches which tend to shoot out far beyond the others 

 should be kept back. Otherwise the tree will lose its symmetrical 

 form and become "shouldered." 



Dead twigs in the fruit-producing area should be removed, and 

 it is generally recommended also to cut out all dead branches in the 

 interior of tne tree. If the orchard has long been neglected and 

 given over to the attacks of scale insects, some thinning out of the 

 branches will be necessary before effective spraying can be done. 

 If this condition has become greatly aggravated, it may be better to 

 cut off all the main branches a short distance from the trunk and 

 allow the tree to form a new head, which it will do very rapidly 

 and will soon again be in condition for fruit bearing. With the ex- 



