104 MANUAL OF TROPICAL AND SUBTROPICAL FRUITS 



attributed to imperfect pollination, attacks of insect pests, 

 and other causes which are discussed in a later paragraph. It 

 seems probable that too much emphasis has in the past been 

 placed on these factors, and that the problem is largely a phys- 

 iological one, connected with the nutrition of the tree. It is for 

 this reason that the two quotations above are illuminative. 

 They show that the nutritional problem has been recognized 

 by early students of mango culture ; yet no one has taken up 

 the subject in sufficient detail to master it. 



The mango requires less water than the avocado, although 

 young trees are benefited by frequent irrigations. In Florida, 

 old mango trees will be found growing and fruiting in fence 

 corners and abandoned gardens where they have to depend 

 entirely on rainfall. They are much more successful under such 

 conditions than the avocado. Orchards of budded or grafted 

 trees are rarely irrigated after the trees have attained a few 

 years' growth. In other regions treatment must be different. 

 In California, for example, irrigation should be practiced as 

 with citrus fruits. J. E. Higgins remarks concerning Hawaii : 

 "Liberal moisture must be supplied to the roots, from 50 to 70 

 inches per year being required, according to the retentive 

 power of the soil and the rate of evaporation. In the case of 

 bearing trees the heaviest irrigation should be given from the 

 time when the flower buds are about to open until several 

 weeks after the fruiting is over, withholding large amounts of 

 water during two or three months preceding the flowering 

 season." Regarding India, Woodrow says: "When fruiting 

 age is attained there need be no necessity for irrigation from the 

 time the rain ceases in September till after the flowers have 

 'set,' that is, till the young fruit appears ; thereafter, irrigation 

 over the area covered by the branches once in fifteen days or so 

 is desirable while the fruit is increasing in size, but may be 

 discontinued when ripening approaches." 



All writers point out the necessity of applying a check to 



