CALIFORNIA AVOCADO ASSOCIATION 



173 



the spring period. The quantity of fertilizer used at each application 

 varies of course with the size of the tree, quantity of fruit it is carrying 

 and the analysis of the fertilizer. For ten year old trees as high as 

 25 pounds at a single application has been used with good results. 

 For four year old trees, bearing their first full crop, four applications of 

 from three to four pounds each, one of four and one half and one of five 

 pounds have brought the trees through the year in fine shape. As 

 materials from which fertilizers suitable for avocados may be compounded, 

 cottonseed meal, castor pomace, tankage, ground tobacco stems and 

 ground bone are to be recommended, with a certain amount of nitrate of 

 soda used as a source of nitrogen when quick results are sought as in 

 the case of trees which have "started back". Previous to the war 

 scarcity of potash, it was thought advisable to use formulae giving 

 from four to six per cent of that element, but the enforced limitations 

 to the percentage of potash obtainable during the past two years has 

 had no apparent ill effects upon the trees or fruit and seemingly a range 

 of from zero to four percent will provide all the potash that an avocado 

 tree requires under Florida conditions. A formula that has given good 

 results is built up of cotton seed meal, castor pomace, tankage and 

 ground tobacco stems, analyzing 4 per cent to 5 per cent ammonia, 6 per 

 cent to 7 per cent phosphoric acid and 2 per cent potash. 



The trees are usually cultivated by hoeing three times each year 

 and a heavy mulching of dead grass or weeds during the dry winter 

 season. If instead of the dead grass a mulching of compost or well rotted 

 stable manure is used the results are even more satisfactory and the 

 February application of fertilizer may then be omitted entirely. 



The foregoing methods are those which have been used by the 

 writer and others, largely with the avocados of the West Indian type. 

 When applied to Guatemalan or Mexican varieties budded on West Indian 

 stock, the results have been entirely satisfactory, but just what changes 

 may become necessary when Guatemalan or Mexican stocks are used it 

 is yet too early to say as these stocks are of quite recent introduction 

 in Florida and the opportunity for observation has been quite limited. 



Climatic differences and soil conditions will undoubtedly make many 

 changes from the Florida methods advisable in the culture of avocados 

 in California, but a few of the essential principles apply to these trees 

 wherever they may be grown and it should not be difficult to work out 

 a cultural program for any locality, the climate of which is suited for 

 the avocado, providing the following points are borne in mind: 



The avocado demands plenty of moisture, but must be planted only 

 on well drained land. 



The avocado is a gross feeder and prefers plant food derived from 

 organic sources. 



The production of a full crop of fruit is a severe drain upon the 

 vitality of an avocado tree and this must be compensated for by adequate 

 nourishment. 



Mulching is beneficial and almost essential. The avocado does not 

 thrive best under conditions of clean culture. 



