ROOT DISEASES 141 



latter crop, so far as the writer's experience goes, the cases are 

 more usually of the deep-seated kind, which does not permit of 

 successful treatment. 



III. — Control. 

 Removal of Diseased Trees. 



When an infested tree is found it is well that its destruction 

 should be prompt, but it is an advantage to choose a dry day 

 for the operation. If the disease is so far advanced that the 

 fungus is producing conidia, either on the stem or on dead leaves 

 and twigs lying about, then before it is disturbed the spore- 

 bearing surfaces should be flamed with a torch or by burning 

 trash of some description around them. This disposes for the 

 time being of the means of aerial dispersal of the fungus, and 

 lessens what is otherwise a real danger of the carriage of infection 

 on the persons and implements of the labourers. 



The diseased tree should be cut down, the stump dug out, and 

 the roots followed up and removed as completely as possible. 

 One planter gets out the fragments with a builder's sieve, and 

 has had unusual success with his supply plants. It is convenient 

 for the labourers to have baskets handy into which the small 

 roots can be thrown as they are dug out, otherwise they are in 

 danger of being scattered. 



The diseased material should be destroyed by fire, preferably 

 on the spot. It has been formerly stated that the whole tree 

 should be cut up and burned, but experience has shown that the 

 necessity for this, which has often been a real difficulty to planters 

 trying to follow instructions, may be avoided. It is easy to 

 note how far the fungus has reached, and if the stem is cut above 

 this point, and the top is disposed of in such a way that it can 

 dry out, it will not develop Rosellinia. This has been verified 

 on trees thrown into the edge of the forest, provided they did 

 not rest upon the ground, and on others perched on large stumps 

 and on rocks. It is better to dispose of even the stump in some 

 such way than simply to leave it lying about as is too frequently 

 done, but all material actually infested certainly ought to be 

 burned. No material, root or stem, infested or uninfested, should 

 be left lying on the ground. In one instance the stem of a cacao 

 tree, some 5 feet long, which had been charred and thrown aside 

 in the grass, was found sheeted from end to end with conidial 

 fructifications, and stems and branches of dead lime trees have 

 been frequently seen, where they have rested for some distance 

 on or close to the ground, in a similar condition. Had they been 

 wedged among the branches of a tree they would have been 

 quite harmless. 



Under some conditions it may be necessary to choose a 

 convenient situation and carry to it material to be burned, but 

 such transportation has obvious dangers in the way of scattering 

 bits of diseased material. It should certainly be preceded by the 



