116 The South African Mulberry Blhjht 



France. He was also shown a culture of a white organism and twigs 

 and leaves blighted by it, which had been inoculated some six weeks 

 previously. The signs, internal and external micro- and macroscopic, 

 on the tree agreed perfectly with the American disease and the streaks 

 looked exactly the same. 



Infected shoots and leaves were sent to Washington; from these 

 Bacterium mori was isolated and successful inoculations made. In 

 view of the fact that both American and French diseases are certainly 

 caused by B. mori, Smith considers that the Italian disease should be 

 re-examined; all the external signs of the disease being identical in 

 both countries. 



Geographical Distribution in South Africa. 



The mulberry blight is very severe in the Pretoria district; I have 

 not seen a single black mulberry (Morus nigra) which has escaped 

 infection. Not only are trees in the town and its neighbourhood 

 affected but in such farms and outlying places as Garstfontein and 

 Onderstepoort. 



It is pretty general in Natal, and specimens have been received from 

 Bloemfontein, 0. F. S., and Pietersburg, Transvaal, very badly infected 

 with the blight. 



Mr R. A. Davis, the Government Horticulturist, informs me that 

 he has never seen the disease in the Western Province of the Cape, 

 and that there one finds very fine specimens of the black mulberry 

 tree. Possibly the winter rains and dry summers are partly accountable 

 for the immunity of the trees in this region, as the new infections on 

 leaves and shoots are only observable in the Transvaal after the first 

 spring rains. 



The common mulberry never becomes conspicuously blighted in 

 nature although it is possible to infect its leaves and shoots with pure 

 cultures of the causal organism. 



At Mr Davis's suggestion we obtained specimens of leaves of several 

 varieties of mulberry grown by Mrs Forbes of Athol in the Erin do 

 district. Of these, M. nigra and M. alba were found to be infected 

 and also another species which has not been identified. This is the 

 only record of varieties other than Morus nigra being found infected 

 with the blight. 



