36 



ANNUAL REPORT 1919 AND 1920 



also known by this name, though the owner of the tree refers to it as "ahuacate 

 verde" or "green ahuacate," because of its color when ripe. 



I will not here enter into a discussion of the botanical differences which 

 distinguish the Guatemalan and the Mexican races, since they have elsewhere been 

 treated as fully as the present state of our knowledge will permit. Suffice it 

 to say that the Guatemalan, so far as we know at present, is a horticultural race 

 of Persea americana Mill. (Persea gratissima Gartn.) developed in or suited to 

 tropical highlands. It withstands more cold than the lowland or "West Indian" 

 form of the same species. The Mexican race (so-called) appears to be a distinct 

 species, Persea drim\)foUa, described by Chamisso and Schlechtendahl in 1 83 1 . 

 Horticulturists in the United States are now familiar with the characteristics of the 

 Guatemalan, West Indian, and Mexican races. 



Most of the avocados observed in Atlixco can easily be classified as either 

 Guatemalan or Mexican. I found a few trees however, whose fruits were rather 

 puzzling. Fuerte is the most noteworthy of these, and after careful examination 

 I believe this to be a hybrid between the two species. Elsewhere in this paper 

 I discuss its characteristics more fully. Several varieties were seen which in most 

 resp)ects resembled the Mexican race, but they were larger in size and had thicker 

 skins than usual. At first I thought that some of these might be hybrids like 

 Fuerte, but on further study I found no evidence which warranted the retention 

 of such a belief. Puebla is one of these varieties, and the others were similar to 

 it in character. 



CULTURAL PRACTICES 



Little can be said regarding the planting of avocados in Atlixco, for it 

 seems rarely to be intentional. The situations in which the trees are found sug- 

 gest that in nwst cases they are volunteers. I have seen a few plants growing in 

 flower pots or tin cans, to be planted later in the orchard; but the groves now 

 in existence do not appear to have been systematically planted. 



No instances were obsen^ed in which avocados had been budded or grafted, 

 or propagated in any way except by seed. While sweet limes are commonly 

 propagated in Atlixco by stem-layering (marcottage) and the pear is occasionally 

 cleft-grafted on the tejocote, no asexual method of propagation seems to be ap- 

 plied to the avocado. 



Sometimes two trees wall not be more than six feet apart, in other instances 

 they may be fifty, or a single tree may stand alongside a small field or patch of 

 cultivated ground. There is no uniformity whatever in this respect. 



Avocados are found in Atlixco under three rather distinct sets of cultural 

 conditions. These are : ( 1 ) trees growing in grain fields, where the ground re- 

 ceives tillage incidental to the planting and cultivation of wheat or maize; (2) 

 trees growing in huertas containing a varied collection of fruit trees and perhaps 

 coffee bushes, and where the ground is occasionally cleaned with a hoe and thus 

 kept reasonably free from weeds and grass; and (3) huertas such as those under 

 (2) except that the ground is not cleaned, weeds and grass being allowed to de- 

 velop unhindered. 



I cannot determine which of these produces the best results, as trees look 

 very much alike under all three sets of conditions. It would require a long 

 period of careful observation to settle this matter. 



Practically the only cultural attention given intentionally to avocados in 

 this region consists of irrigation during the dry season, — October to May. 

 Throughout this period water is run thru the huertas every 15 to 30 days. The 

 typical Atlixcan avocado grower turns the water into his huerta thru a small 



