32 MANUAL OF TROPICAL AND SUBTROPICAL FRUITS 



California they should not be spaced closer than 24 by 24 feet, 

 making 75 to the acre ; 30 by 30 feet (48 to the acre) is 

 preferable. 



Holes for planting should be prepared a month in advance, 

 with a small quantity of fertilizer incorporated in each. Barn- 

 yard manure is commonly used for this purpose in California, 

 while South American goat manure and pulverized sheep manure, 

 2 or 3 pounds to each hole, have proved satisfactory in Florida. 



In planting, the tree should be set so that the point of 

 union between the bud and the seedling stock is slightly above 

 the surface. Deeper planting may not be objectionable in 

 California, but in Florida shallow planting seems to be best. 

 A liberal watering should be given immediately after planting. 



Tillage, mulching, and cover-crops. 



The ground around the young trees should be kept liberally 

 mulched with weeds, straw, barnyard litter, seaweed, or any 

 coarse material which is not injurious and will not pack and 

 form a layer impervious to air and water. Through the winter 

 a mulch is not necessary in California, but in Florida it has been 

 found desirable, in some sections at least, to maintain one 

 throughout the year. In Porto Rico, G. N. Collins observed 

 that the avocado tree was seldom, if ever, found in perfectly 

 open places, with the bare ground around the roots exposed 

 to the sun. While this principle applies more particularly 

 to Florida and other regions distinctly tropical in character, 

 it may be proved to hold good in California as well. Definite 

 knowledge on this point is still lacking. Up to the present 

 it is the practice of many California orchardists to cultivate 

 the soil regularly after each irrigation, as with citrus fruits. 

 Deep cultivation seems to produce no harmful results in Cali- 

 fornia, where the roots go far down into the soil, but in southern 

 Florida it must be practiced with caution. In this region the 

 feeding roots extend practically to the surface, and deep culti- 



