102 



1917 ANNUAL REPORT 



of the experienced growers in California favor the use of the Guatemalan 



type. 



Many varieties that are frequently mentioned in discussions are not 

 included in this list. The list must be taken merely as the best judgment 

 of the committee, at the present time, of the varieties safest to recommend 

 for planting. Several very promising varieties are not mentioned, as the 

 know^ledge of the committee concerning them is insufficient to justify passing 

 judgment on their qualities and comparative value. Again, some of the 

 varieties mentioned in the list will probably be discarded later. This list, 

 the committee expects to be of temporary value only. It should be revised 

 by the Association every year and brought up to date to keep pace with 

 advancing knowledge. As soon as justified by experience, varieties of other 

 types should be included. 



Explanation of List 



The varieties are listed according to season of maturing and not in 

 the order of their merit. It is well recognized by growers that the season 

 of maturing of a given variety is very variable and may extend more or 

 less throughout the year. The placing of a variety in a definite season 

 merely indicates its usual season of maturing when it may be expected to be 

 at its best. Varieties may extend from one season into another, and when 

 in the judgment of the committee, a variety may be considered as import- 

 ant in two seasons, it is listed under both. It thus happens that several 

 varieties are listed twice. 



The percentages of oil or fat given under each variety are taken 

 from analyses made by Professor M. E. Jaffa, of the University of Cali- 

 fornia, except in the case of the Spinks, which is from an analysis made by 

 E. M. Chace of the U. S. Department of Agriculture. These are not 

 averages, but are the highest percentages found in any single analysis of a 

 variety. The percentage of fat increases as the fruit matures and in view 

 of the few analyses that have been made of any one variety, it is thought 

 to be more instructive at present to give the highest analysis rather than an 

 average. 



The other descriptive information relative to the varieties listed is self- 

 explanatory, but it must be remembered in using the list, that there are 

 many variations and extremes that cannot be given in a condensed table. 



Avocado orchards require several years to reach full bearing age 

 and size, and it is a somewhat common practice to plant the orchard more 

 thickly than is ultimately desired, using some regularly devised system pro- 

 viding for the removal of a certain number of the trees. The trees that are 

 intended to be removed are ordinarily spoken of as filler trees. Special 

 attention is directed to the value of the Lyon for use as a "filler" tree in 

 planting. Its upright habit of growth and early fruiting render it particu- 

 larly valuable for such use. 



ROOTSTOCKS FOR THE AvOCADO 



So much injury may be done by the use of tender or poor rootstocks 

 in the propagation of the avocado that the committee would strongly 

 recommend that only seedlings of the hardy Mexican avocado be used 

 for budding and grafting stocks. Nurserymen should use this type of root- 

 stock only for trees propagated for sale, and planters should demand that 

 the trees purchased for planting should be on this stock. Seedlings of the. 



