DISEASES OF MINOR FRUIT TREES 237 



vine, is common in Barbados and Trinidad. It affects leaves, 

 young shoots, flowers and fruit, appearing in the form of white 

 powdery patches, which may later cover the affected part. 

 The effect of the mycelium on the surface is to cause brown, more 

 or less fern-like markings, and the infestation of young and 

 tender organs stops their development 



The disease is most prevalent in humid weather, and arrange- 

 ments to give access to sun and air reduce the tendency to its 

 development. The best means of control is dusting with sulphur 

 or with sulphur and lead arsenate mixture, which if carried out 

 under proper conditions (see p. 106) is highly effective. 



Rust. 



The older leaves of vines and, in conditions less suitable 

 for growth, the young leaves as well, are liable throughout 

 the West Indies to infestation with a rust fungus, which produces 

 large numbers of small pustules, giving off powdery yellow 

 urediniospores, mostly on the underside of the leaf. The fungus 

 from several West Indian localities has been determined by 

 J. C. Arthur as Phakopsora vitis (Thum.) Syd. 



Probably the best means of dealing with it consists in giving 

 increased attention to cultivation, thus tending to confine its 

 attacks to old leaves which have largely passed their period of 

 usefulness. Spraying might also be tried. 



Mango. 



Mangoes are grown as scattered trees, for roadside shade, 

 or as windbreaks throughout the islands, much less commonly 

 in Barbados, however, than elsewhere. Trees producing good 

 quality fruit, propagated by grafting, are found only in gardens 

 or mixed orchards. Apart from the anthracnose described below 

 and one or two leaf- spots of no importance the tree is not known 

 to be subject to disease, except where it comes in contact, usually 

 in cacao plantations, vnth the fungus Rosellinia Pepo, to the at- 

 tacks of which it is, moreover, not very susceptible. 



Anthracnose. 



A fungus affection comprising a leaf-spot, blossom blight, 

 and fruit spot is fairly general in Florida and throughout the 

 West Indies, and is destructive in some seasons and situations 

 on the flowers and setting fruit. 



The spotting of older fruit does not appear to be a very 

 notable character of the disease as it is met with in the smaller 

 islands. The description of this is derived from an account 

 by J. B. Rorer of the various phases of the affection as they 

 occur in Trinidad. 



