Volume II JULY, 19i:> Nos. 2 and 3 



THE SOUTH AFRICAN MULBERRY BLIGHT 

 BACTERIUM MORI (BOY. and LAMB.) SMITH. 



By ETHEL M. DOIDGE, M.A., F.L.S. 



Mycologist, Division of Botany, Pretoria. 



(With Plates XIX-XXIV.) 



For some years it has been evident that the finer varieties of the 

 mulberry, particularly the one known as the "English mulberry," do 

 not thrive in certain districts of the Union. I have seen trees of this 

 variety 14 years old which have only attained to a height of three to 

 five feet. In other districts the black mulberry grows well, and fine 

 trees may be seen, so that the failure cannot be attributed to unsuit- 

 ability of climate; the readiness with which the common mulberry 

 grows would also go to disprove such a supposition. The general 

 appearance of the trees suggests that they are suffering from some 

 blight: a number of the tips of the branches are dead, and the leaves 

 towards the end of the season become covered with small brown spots. 



In November, 1908, leaves and twigs so affected were sent in for 

 examination from a farm in the Pretoria district and the diseased areas 

 were found to be occupied by countless swarms of bacteria. No fungus 

 was found in connection with the disease, so that the bacillus was 

 probably the causal organism, and culture work was undertaken in 

 order to discover whether or not the South African mulberry blight 

 is identical with that known in Europe and America. 



The literature on the mulberry blight shows that the disease has 

 been attributed to two entirely different bacilli, and it therefore becomes 

 necessary to briefly review such literature in order to compare the 

 characters ascribed to these organisms. 



Ann. Biol, n 8 



