Investigations on the Mulberry Dwarf Troubles, 

 a Disease widely spread in Japan. 



BY 



U. Suzuki. 



In a former number of this Bulletin (Vol. IV, No. 3) I have 

 described how widely distributed this disease is and how much 

 'damage is caused by it. The general diagnosis was given, 

 numerous analyses were carried on to find out the differences in 

 chemical composition of the healthy and the diseased plants ; 

 the relation of reserve materials to the disease was especially 

 investigated, and extensive field experiments were further made 

 and many facts observed with plants from different provinces. 

 From my studies I came to the conclusion that the disease was 

 not caused by any parasite, but the primary cause was to be 

 sought in the practice now in vogue of subjecting the mulberry 

 tree to repeated cuttings in the growing season. During winter 

 a considerable amount of reserve materials (especially nitrogen 

 compounds and starch) is stored up in the bark of stems and 

 roots, while in spring, when the development of new leaves 

 commences, the greater part of it is transported to the growing 

 shoots. The assimilation products in the leaves again migrate 

 to the stems and roots in late autumn, when the leaves begin 

 to fall. Therefore the stems and roots are rather poor in 

 reserve materials during the growing season. Now it will be 

 at once evident that the cutting of the plants in the growing 

 season must have a very bad effect on the shoots that develop 

 later on, since the supply of reserve materials upon which they 

 depend is but very scanty. Moreover, it is not impossible that 

 the stored materials may be entirely exhausted before the new 

 shoots have attained a certain height and have become able to 

 prepare their own organic food by assimilation. In such a case 



