137 



40. The Root-disease is, without doubt, the most serious ; it is 

 widely distributed, and is causing considerable loss in the Guapo 

 and Cedros districts and in some of the heavy undrained inter- 

 lands at Mayaro, as well as in smaller areas at Laventille and 

 Cocorite, while it has been reported from Toco and Guayaguayare. 



41. It is apparently caused by a fungus, a species of Botryodip- 

 lodia, and may be recognised by the yellowing and hanging down 

 of the leaves, by the disorganised condition of the cortex of the 

 roots, by the red ring of discolouration that may be seen in the 

 stem, and by the pustules bearing fungus spores that are in- 

 variably seen, sooner or later, on the dead petioles. 



42. There are reasons for concluding that the disease is pri- 

 marily one of the roots, and, although the mycelium of the fungus 

 present in the roots is not continuous through the stem with that 

 in the petioles, experiments tend to indicate that they are of a 

 similar nature, and, therefore, the petiole trouble, though second- 

 ary in destruction may be one of the primary means of distribution 

 of the disease. 



43. The disease may spread through the soil by means of my- 

 celium, by spores blown by the wind from tree to tree, and by 

 means of the fall of diseased petioles, while replanting of sup- 

 plies on diseased spots without proper cultivation and treatment 

 may be a means of continuing the disease in the next crop of 

 trees. 



44. The disease appears in all soils, but apparently spreads the 

 more rapidly and is the more destructive in damp, low-lying, 

 undrained hollows. Careful attention to drainage, cultivation 

 and application of manures should increase the vigour of the trees 

 and render them less susceptible to attacks of disease. Undrained, 

 uncultivated, neglected portions of any estate are a standing- 

 menace to the whole estate and perhaps the whole district. 



45. To prevent further spread of the disease, the following 

 remedial measures has been suggested : — ■ 



(a) All dead or dying trees, diseased leaves and petioles that 

 have fallen to the ground, rubbish, etc should be des- 

 troyed, either by fire or by burying deeply with lime. 



All stumps should be grubbed up and as many diseased 

 roots as possible destroyed. 



(b.) When small areas are noticed, they may be isolated from 

 the remainder of the estate by digging a good trench 

 around them. This should prevent spread of mycelium 

 in the soil to other portions of the estate. 



(c.) Resting and cultivation of infected land that has been 

 cleared and burnt before replanting ' supplies.' 



(d.) Spraying and application of chemicals to destroy spores 

 and also mycelium in the soil. 



(e.) Replanting should be clone with ripe nuts from disease- 

 resistant trees if such can be found. 



46. The leaf disease is limited to small areas, which are appar- 

 ently in want of better cultivation, and seeing that a similar 

 disease has caused considerable damage to coco-nuts, especially 



