E. M. Doidge 123 



Summary. 



1. The black mulberry (Morus nigra) is very subject in South 

 Africa to a blight affecting twigs and leaves. 



2. The blight is fairly widespread but certain districts, particularly 

 the western part of the Cape Province, are as yet free from it. 



3. Spraying with Bordeaux mixture is useless in controlling the 

 disease. 



4. The organism causing the blight was isolated and numerous 

 infections obtained with pure cultures. 



5. The morphological and cultural characters of the organism 

 correspond with those of Bacterium mori which causes the French 

 and American mulberry blight. 



6. The bacterium as isolated from leaves of blighted trees in 

 South Africa has one to four polar flagella. This is the only important 

 variation from the organism as described in America. Smith describes 

 it with one, sometimes two, polar flagella. 



Botanical Laboratories of the Union op South Africa, 

 Pretoria. 



Acknowledgment. 



The investigation which forms the subject of this paper was carried 

 out in the Union Phytopathological Laboratories which are under the 

 direction of Mr LB. Pole Evans, M.A., B.Sc, F.L.S., Chief of the 

 Division of Botany. 



I have to thank Mr R. A. Davis, Chief of the Division of Horticulture, 

 for naming the varieties of Morus and for valuable information as to 

 the distribution of the disease. 



LITERATURE. 



(1) Boyer, G. et Lambert, F. Sur deux nouvelles maladies du murier (Compt. 



Rend, cxvn, 1894). 



(2) Cuboni, G. e Garbini, A. Sopra una malattia del gelso in rapporta colla 



flaccidezza del baco da seta (Atti R. Acad, del Lincei Rendic. 4, ser. vi, 

 1890, Fasc. 1). 



(3) Macchiati, L. Contribuzione alia biologia dei batterii dei bachi affetti da 



flaccidezza (Stazione sperim. Italiane, vol. xxi, Fasc. 2, 1891). 



(4) Macchiati, L. Sulla biologia del Bacillus cubonianus n. sp. (Malphigia, v, 



1892, p. 289). 



