202 DISEASES OF CROP-PLANTS 



the soil in the way of ignoring drainage, and, in some instances, 

 packing it by the constant pasturing of cattle. As starvation 

 takes effect one or more sections of the tree begin to die back 

 branch by branch, and not only the dead but the failing branches 

 become infested with fungi. The removal of the dead branches 

 does little to arrest the process ; the wood of the next larger 

 branch or stem is usually already infected, and offers little 

 resistance to the progress of decay. In the course of time the 

 base of the tree is reached by way of the stem or stems involved, 

 and permanent restoration is no longer possible. Growth is 

 usually continued by suckers put out around the base, which 

 may attain to a considerable size, and give the tree a renewed 

 lease of life. In time rotting of the central part of the 

 crown, due to the downward extension of decay from the original 

 stem, destroys the connection berween the suckers, depriving them 

 of mechanical support, and leaving them with exposed wood on 

 their inner sides in the neighbourhood of soil level. They are 

 rarely able to establish themselves as permanent stems, and sooner 

 or later, from the weight of the crop or the force of the wind, 

 they fall outward, or are broken off. The process of failure 

 thus outlined is a gradual one, commonly extending over some 

 years, and seems in consequence to be usually regarded with 

 indifference until the end result appears. There is, even in the 

 worst cases of this type seen in Dominica, no question of quick 

 destruction of trees such as is produced by an active parasite 

 like Rosellinia. 



It has been further noted in cases where lime trees have been 

 grown on poorish land, and without manure, and have in con- 

 sequence grown slowly from the beginning, that, although they 

 may develop dead branches in the course of time, their wood 

 does not appear to be nearly so susceptible of decay as is the case 

 with trees which have grown more quickly. 



Control. 



The remedial and preventive measures which should be 

 adopted are clearly indicated. In fields where dieback is in 

 evidence, or where small and scanty foliage shows that the trees 

 are lacking in vigour, the first essential is to restore the fertility 

 of the soil. If it has become consolidated, or is covered with a 

 firm sod, it should be lightly forked ; as much organic material as 

 can be obtained in the shape of pen manure, mulch, cotton-seed 

 meal, lime seeds, and sheep manure should be applied ; the 

 weed growth, if rank, may be cutlassed and used as mulch 

 towards the end of the wet season. Leguminous cover crops 

 may be grown if there is light enough for their development. 



At the same time the work of clearing the trees of dead and 

 sickly branches should begin. Men who have received instruction 

 in this work should be kept to it as much as possible, and it will 



