E. M. Doidgk 5 



At the suggestion of Mr R. A. Davis, we communicated with 

 Mr Cousins, Director of Agriculture in Jamaica, who has devoted 

 considerable time and study both to the cultivation of the mango and 

 to the diseases to which it is subject. Mr Cousins wrote in reply : 



" This disease is quite unknown in Jamaica. The mango sometimes 

 suffers from the attack of thrips on the young foliage but otherwise is 

 almost immune from disease and pests in Jamaica." 



The majority of the trees in Natal were grown in the first instance 

 from seed imported from Mauritius. Mr Bijoux, the Assistant Director 

 of the Botanic Gardens, Mauritius, was visiting Durban in December, 

 1911. He stated that when he left the island the trees were perfectly 

 healthy and laden with fruit. He knew nothing of the occurrence of 

 such a disease. This information was obtained through the courtesy 

 of Dr Medley Wood. 



To summarise : so far as can be ascertained, there is no evidence of 

 the occurrence of this disease outside South Africa. In all the mango- 

 growing districts of the Union with the exception of the Zoutpansberg, 

 the disease has caused considerable loss. Swaziland is also free from 

 infection. In Portuguese East Africa cases of infection have only been 

 reported from the neighbourhood of Delagoa Bay. 



Symptoms of the disease. 



Although the effects of the disease on the fruit are the most con- 

 spicuous, and of the greatest importance economically, numerous 

 infections also occur on stems and leaves. The latter do not greatly 

 affect the general health of the tree, but they serve to carry over the 

 infection from one season to the next. 



The first signs of infection noticeable on the leaves are a number of 

 small, angular, water-soaked areas bounded by some of the veins of the 

 leaf. These spots do not increase much in size and rarely exceed 

 2 — 3 mm. in diameter ; but if they are very numerous they coalesce and 

 larger spots are formed. The infected areas soon begin to discolour 

 and become dark brown, the surface is somewhat raised and shining 

 and frequently there is a slight exudation of gum (Plate II). In very 

 old leaves these discoloured spots become white and dry, and crack 

 away. If infection takes place in the petioles — as is often the case — 

 longitudinal cracks result which attain a length of 1 cm. or less. 



Diseased spots are also found on all parts of the stem, although it is 

 evident that the majority of the infections take place in young and 

 rapidly growing tissues ; they are also common in the scars from which 



