134 



paratively insignificant, the damage done to plants attacked by Black 

 Blight being almost entirely damage l>y scale insects. 



10. Several trees are always to be. seen which show the Black 

 Blight on leaves and twigs. The most striking of these are : — 



The Clammy Cherry ... ... Cordia Colloccca. 



Mango ... ... ••• Mangifera Indira. 



Breadfruit ... ... Artocarpus incisa. 



Sapodilla ... ... ... Sapota Achras. 



Guava ... ... Psidium guava. 



Limes ... ... Citrus Medico, var acida. 



Oranges ... ... ... Oitrus Aurantium. 



Black Blight also seems able to subsist on the products of several 

 different kinds of scale insects prominent among which are the 

 following: — All the species of the shield scales (Lecanium) ; the 

 glassy star scale (Vinsonia stellifera) ; the mussel scale (Mytilaspis 

 citricola) ; and the mealy shield scale (Protopulvinaria piriformis). 

 Many of the plants affected by these scales, and the attendant black- 

 blight, live on year after year though the upper surfaces of all leaves- 

 seem to be thickly coated with the mycelium of Capnodium and the 

 under surfaces and small twigs seriously attacked by scale insects. 



11. No serious attack of Black Blight, or the scale insects 

 causing it. have yet been observed on cacao or nutmeg and it, may be 

 stated as a general truth that, until the scale insects attack these 

 plants, the Black Blight will not. and that any observant planter 

 will be able, to detect the beginnings of such attack, and by the 

 application of contact insecticides will be able to ward off the attack 

 before it assumes serious proportions. The fact that for so many 

 years cacao has been grown in these islands where many of these 

 scale insects are native, and cacao has never been seriously attacked 

 by them would lead to the supposition that it is not a favourite, food 

 plant for the scales. 



12. Mr. MacNeill. Agricultural Instructor, in a letter dated 

 December, 1902, gives a long list of plants affected by black blight 

 and says " When mangos, breadfruit and other trees become affected 

 with the blight, the crops suffer and I have heard of cases where the 

 trees died,*' but he does not say from his own knowledge that black 

 blight doe- kill trees, or thai he has ever seen trees that he considered 

 had been killed by this pest. As bearing on this point I would refer 

 to the mango. This tree, in many places is affected year after year by 

 the black blight and vet each new crop of leave- comes on and fully 

 recovers the tree so thai with the casting of the old leaves and the 

 bursting of the new. the tree stands to all appearances a clean and 

 healthy tree. Many affected leaves are left however, and in a short 

 time the scale insects take possession of the new growth and the black 



(ungUS SOOn appears on the leaves which were clean. 



L3. When in Grenada, I noticed that the trees in the vicinity oi 

 St. George's were much more, commonly attacked l>\ black blight than 



along the leeward coast and in the northern part of the island. What 



conditions are responsible for this I am not able to say. bul 1 presume 



that the more unnatural nature of the locality leads to this prevalence. 



1 I. The extermination of Black Bligh.1 in an island like Grenada 



