Edible Products. 



144 



most important factors. Trees can be seen growing in a great variety of soils, but 

 always in localities with good drainage. On the other hand, they are seldom, if 

 ever, found in perfectly open places, with the bare ground around the roots exposed 

 to the sun. The heavy clay soil common in Porto Rico seems well adapted to their 

 culture, provided the trees are placed on ground sufficiently sloping to secure good 

 drainage. The avocado is at present absent from the low, flat lands of the island 

 and it is extremely doubtful whether it would succeed in such localities. 



CLIMATE. 



The avocado in its native state is a strictly tropical plant, and none of the 

 varieties thus far recorded is able to stand any but the lightest frosts. Although 

 requiring tropical conditions, it thrives best in a somewhat more moderate climate 

 than the mango, and it will seldom be seen in the extremely hot localities where the 

 mango often luxuriates. This may, however, be due to a lack of sufficient moisture, 

 as well as to the high temperature. On the other hand, the avocado will be found 

 growing at much higher altitudes, and here again it is not plain whether the reduced 

 temperature or the increased moisture is the determining element. To be successfully 

 grown, the tree must be planted in protected situations if the locality is at all subject 

 to high winds ; for the wood is not strong enough to withstaud any severe strain, 

 while the large fruit would, of course, be beaten off by any high wind occurring when 

 it was reaching maturity. In Guam, according to Mr. W. E. Safford, although repeat- 

 edly introduced, the avocado has never succeeded, owing to the hurricanes, which 

 invariably kill the trees that otherwise do well. The injury in this case is due to the 

 excessive rainfall as well as to the high wind, a wet situation being fatal to this plant. 



CULTIVATION. 



The avocado is seldom regularly cultivated, so that little can be said of it in 

 this connection except in the way of conjecture. The best fruit now produced is 

 probably from trees that receive little or no care. This may, however, be due to the 

 fact that the countries where such fruit is grown possess superior varieties, or that 

 the natural conditions are more favourable, and should not be taken as indicating 

 that the fruit cannot be improved by cultivation. In Porto Rico the trees in their wild 

 state are such prolific bearers that there seems little to be desired in this direction. 



The avocado would probably receive little or no benefit from having the 

 ground about its roots stirred, as it is almost impossible to do this and prevent 

 washing from the severe rains, and it is much better to secure protection from some 

 low-growing plant that will not exhaust the soil. Leguminous plants would doubt- 

 less be the most satisfactory, and in Porto Rico there are several that could be so 

 utilized. Some useful plant belonging to this group might serve as a catch crop and 

 at the same time afford the necessary protection to the soil . In France it has been 

 recommended that grafted plants be grown on fruit walls, in the same manner as 

 citrus trees. 



IMPROVEMENT. 



If experiments in improving avocados through breeding have been tried the 

 results seem never to have been published. Individual growers must have done 

 more or less selecting, and accounts of their results would doubtless be of consider- 

 able value to breeders. The points to be kept in mind in any attempt to improve 

 the avocado are:— (1) Shipping qualities, (2) uniformity, (3) extension of season, 

 (4) seed reduction, (5) texture, ((5) flavour, (7) yield, (8) size, (9) resistance to cold. 



Shipping Qualities.— To the growing of avocados in other than sub-tropical 

 regions there is perhaps no obstacle so great as the difficulty of placing the fruit on 

 the northern markets in good condition. To overcome this, more can be expected 

 from the introduction of new varieties and improved methods of packing and shipping 

 than from any changes brought about by cultural means. Any advance, however, that 

 can be made in the keeping and shipping qualities will be of the greatest importance, 



