MULBERRY- DWARF TROUBLES IN JAPAN. 



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b) . The disease is not observed where the plants are not cut, 



and even plants already diseased may recover when 

 kept from cutting for some years. 



c) . Many experiments show that cutting in the growing 



season is followed by the disease, while it is not 

 observed when the plants are left without cutting. 



d) . The disease is not induced when the stems are cut during 



winter or in early spring before the leaves are un- 

 folded. 



3. Not only by cutting in the growing season, but also by 

 frequent picking of the leaves, the reserve materials in the roots 

 and stems, may be exhausted, and the new leaves developed 

 subsequently become diseased, as proved by many experi- 

 ments. 



4. Some varieties, such as Takasuke, store up a large 

 quantity of reserve materials, while others, like Jumonji, contain 

 comparatively little. The former need a far greater amount of 

 reserve materials during the devlopment of the leaves, while 

 the latter require only a comparatively small amount. This 

 indicates that Takasuke has a weaker absorptive power for soil 

 nutriments in the first stages of development. So it must be 

 very difficult for it to counterbalance the deficiency of reserve 

 materials with the nutriments absorbed from the soil. The con- 

 sequence is that Takasuke is more liable to the disease than 

 Jumonji. But such a propensity is not absolutely confined to 

 certain varieties ; on the contrary, it must have a wide range of 

 variation even among the same variety and is subject to 

 modicification by various conditions. Generally speaking, a plant 

 becomes more liable to the disease by accelerating its growth 

 with abundant soluble manures, and by some other treatment. 

 Therefore no variety would be absolutely free from the disease 

 if they were cut in the growing season, or if the leaves were 

 picked frequently. 



5. Young plants become very rarely diseased. This may 

 be due to energetic development of the roots and a large capaci- 

 ty for the absorption of nutriments in the young plants ; while 

 old plants have less power of developing new roots, and consequ- 



