20 BULLETIN 542, U. S. DEPARTMENT OF AGRICULTURE. 
though it is very common for the lower laterals to produce nothing 
but staminate flowers and the perfect flowers to be limited to the 
laterals on the upper half of the panicle. 
SUMMARY. 
Attacking the problem of mango sterilit}- from several angles, as 
herein outlined, it has been possible to ehminate several factors here- 
tofore generally believed to have some bearing on the question. 
Apparently the difficulty is not due to any morphological defect in 
the pollen or to defects in the mechanism of pollination. By the ex- 
clusion of these factors and from the observation of trees in Florida and 
other regions during several seasons, the conclusion has been reached 
that the problem is a physiological one, connected with nutritional 
conditions as influenced by changes in soil moisture and food supply, 
principally the former. While such factors as lack of pollinating 
insects and loss of pollen through excessive rains may at times have 
an injurious effect upon the mango crop, it seems safe to assert that 
the question of pollination is of comparatively little importance from 
a practical standpoint. Experiments have been undertaken, with 
the cooperation of Prof. E. J. Kraus, to test the practicability of 
inducing the formation of flower buds through ringing, girdling, and 
banding the limbs with wire. The work of Prof. Kraus at the Oregon 
Agricultural Experiment Station 1 with pomaceous fruits has sug- 
gested various methods of this nature, and the results of these experi- 
ments with the mango will be watched with interest. At various 
times excellent results have been reported from ringing and girdling 
the mango, but systematically arranged experiments along this 
line have not been undertaken. It may be that ringing the mango 
should become a standard orchard practice, but it is hoped that 
from the present experiments it will be possible to learn more 
concerning the pl^-siology of fruit setting in the mango and thereby 
establish other orchard practices, such as cultivation or pruning, best 
adapted to insure commercial crops of fruit. In Cuban experiments, 
fertilizers very rich in potash have 3 T ielded good results in the way of 
increased fruit production. It is to be hoped that such experiments 
as these will bring to light a practicable method of encouraging the 
formation of fruit buds on soils or under climatic conditions which 
normally tend to produce vegetative growth to the exclusion of 
reproduction. 
i Kraus, E. J. The study of fruit-buds. In Oreg. Agr. Exp. Sta. Bui. 130, p. 12-21, fig. 15-23. 1915. 
WASHINGTON : GOVERNMENT PRINTING OFFICE : 1917 
