225 



possible of the leaves at the base of the cutting. The effect of 

 sulight in killing the spores which is made use of in this instance has 

 been referred to above. 



A similar disease was reported by W. V, Tower from Porto 

 Rico in 1906, in the Annual Report of the Experiment Station of that 

 island. 



Leaf Spot: Spots varying considerably in size and shape were 

 found to oocur on the leaves of the pine-apple. In typical instances, 

 the spots consist of a straw-coloured central area surrounded by a 

 dark margin. A black central portion may occur within the 

 straw-coloured area, or scattered black blotches may be found; both 

 of the appearances are due to the formation of the macrospores of 

 Thielaviopsis paradoxa. Sometimes, long white arms extended from 

 the black border, at others the spots are white or straw-coloured 

 throughout. The internal tissue is soft and decayed at first, but 

 soon dries and leaves the injured area dry and sunken. 



The fungus gains an entry through wounds in the surface. 

 These may be due either to grasshoppers, which feed on the leaves, or 

 to the effect of the spines and edges of other leaves. The punctures 

 made by a scale insect {Diaspis hromeliae) do not appear to act as 

 sources of infection. The disease is much more prevalent in damp, 

 shady weather than at other times, as in bright, sunny weather the 

 spores of the fungus are killed. The injury caused by this disease 

 in Hawaii was not sufficient to justify the expense of remedial 

 measures. It is clear, however, that any means tending to reduce 

 the general prevalence of the fungus would not be without their 

 effect on this disease also. A similar disease was reported by G 

 L. Fawcett from Porto Rico, in 1908. 



(The Agricultural News of West Indies Vol. X p. 142). 



