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 sterility from several angles, as 

 herein outlined, it has been possible to eliminate 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 * 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 

 fine 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 physiology 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 yielded 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 : GOVKUN MEM WUNTING OFFICE : 1017 



