ROOT DISEASE OF COCOA TREES 109 



Dense shade and excessive moisture favour the develop- 

 ment of the parasite, so that when these conditions obtain 

 they should be remedied. All affected fruits should be 

 collected and buried with lime, which destroys the disease 

 producing organisms. Where the disease is prevalent 

 it would be also advisable to treat in a similar manner 

 the shells of ripe fruits from which the beans have been 

 extracted. Should the disease show signs of developing 

 into an epidemic spraying the trees with Bordeaux 

 Mixture must be resorted to. 



Another species of Phytophthora, viz. P. Faberi, 

 Maublanc, is responsible for cocoa fruit disease in 

 Ceylon, and it has already been shown that spraying 

 with Bordeaux Mixture was attended with satisfactory 

 results. 



Root Disease. — The roots of cocoa trees have been 

 frequently found attacked by fungus mycelium, the 

 parasite being unidentifiable as no reproductive bodies 

 were discovered. Barber investigated such a disease 

 in Dominica in 1892-3, as also did Howard in Grenada 

 some nine years later. A similar disease has been re- 

 ported from Jamaica and St. Lucia, and the writer has 

 recently observed the roots of cocoa trees affected in a 

 like manner in San Thome. 



Although no reproductive bodies were found in the 

 latter case the general habit and effects closely resemble 

 those of Armillaria mellea. An affected tree presents 

 an unhealthy appearance. The foliage is under-sized 

 and of a yellowish hue. Gradually the young branches 

 die and eventually the whole tree may be destroyed. 

 It is not infrequent to find several contiguous trees 

 affected in this manner. 



Diseased roots turn black and eventually decay. Upon 

 careful examination white mycelial threads are observed. 

 These frequently form a web between the bark and the 

 woody tissues of the root. The interior tissues are also 

 permeated by the mycelium, and when all the principal 

 roots have been attacked the tree dies. Although the 

 young mycelium is white it later becomes grey and eventu- 

 ally may assume a pale brown tint. 



The underground mycelium passes from the roots of 

 one cocoa tree to those of another providing they be 

 adjacent, or it may in the same way pass from a cocoa 



