508 Bulletin 94 



practice is not desirable in bearing orchards, as the trees need all the 

 available plant food. Generally, alfalfa should not be grown in the 

 orcliard for more than two or three years or until the roots have pene- 

 trated to a sufficient depth in the subsoil to make possible better 

 aeration for the trees. 



FERTILIZING 

 Olive orchards must be well supplied with plant food, otherwise 

 they will not produce maximum crops of large fruit, x^ccording to 

 analyses made by the Experiment Station chemists, most Arizona soils 

 contain an abundance of the essential elements of plant food, except 

 nitrogen, which can be supplied through the use of leguminous cover 

 crops and stable manure. Usually, if cover crops are grown and the 

 orchard is cultivated, first-class olives can be produced without using 

 artificial fertilizers. 



IRRIGATION 



The olive will remain alive with a very meagre supply of water, 

 but it will not bear fruit. Measured by the standard of common 

 fruits it requires approximately the same amount of water as the 

 deciduous fruits, and about one-half as much as the citrus fruits. 

 Unless careful attention is paid to the amount and time of irrigation, 

 the orchard will not respond with regular crops of first-class fruit. 

 There are three special periods when bearing orchards should be irri- 

 gated, based on the yearly life cycle of the tree. The first irrigation 

 should be in early spring before the trees come into blossom. The 

 application of water during blossoming often causes the flowers and 

 young fruit to drop. The second irrigation should be in the middle 

 of summer, while the fruit is in the growing stage, and the third one 

 in September, as the fruit is nearing maturity. The last irrigation 

 materially increases the size of the fruits and is an important matter 

 where the crop is grown for pickles. In the absence of winter rains 

 one or more irrigations are necessary during this season. 



PRUNING 

 Unless young trees are properly trained, they will not form strong, 

 well-placed branches ; nor will bearing trees produce regular crops of 

 large, good-quality fruit if not carefully pruned. 



