114 The South African Mulberry Blight 



Literature. 



In Italy the mulberry blight has received considerable attention 

 owing to its supposed connection with the disease of silkworms known 

 as "flacherie." The work of the Italian writers will be considered first. 



The blight on the leaves was first studied in 1890 by Cuboni and 

 Garbini (2), who attributed the trouble to a Diplococcus. They claimed 

 to have isolated the organism in pure culture, and with it to have 

 reproduced the disease in healthy trees. They held that this Diplo- 

 coccus was related to, though not identical with, Strejrtococcus bombycis 

 (Fliigge) the causal organism of "flacherie" and found that it was 

 pathogenic to silkworms. 



Macchiati (3, 4, 5) working in the years 1891-2 also found the 

 bacillus parasitic on the mulberry pathogenic to silkworms but quite 

 distinct from Streptococcus bombycis. He studied the organism more 

 fully and named it Bacillus cubonianus. 



Voglino (10) published a paper on the bacteriosis of the mulberry 

 in 1894. He isolated from affected tissues an organism pathogenic 

 to silkworms; however, his description of this organism does not 

 agree with that of B. cubonianus and his results have not been confirmed 

 by more recent workers. 



The most recent of the Italian writers is Peglion (7), who in 1897 

 confirmed Macchiati's work and gave an account of the disease and the 

 organism causing it. A brief resume of this paper follows in order 

 that the characters which he assigns to B. cubonianus may be compared 

 with those of Bacterium mori to which the disease has been attributed 

 by French and American writers. 



The first traces of disease are found on the leaves, a slight discolora- 

 tion of the parenchyma being noticeable at certain points, especially 

 if the leaf is held up to the light. Many of the spots affect the veins, 

 then the leaves become curled and wrinkled, and in any case they 

 become torn and finally reduced to tatters. The young shoots are 

 also attacked; first of all projecting blisters are formed, bright brown 

 in colour, later they become dull and sunken. The first apical internode, 

 where the tissues are tender, is usually the one attacked. The infected 

 area extends in the form of a streak 3-4 cm. long; if only one side of 

 the shoot is affected it causes curvature, but frequently the affected 

 area extends all round the shoot, in which case the extremity wilts 

 and falls. 



From such tissues a yellow bacillus was isolated, which rapidly 



