DISEASES OF COTTON 283 



of loggerhead is that its appearances have mostly been made in 

 fields planted out of the normal season. 



There is no evidence of direct relationship between curly-leaf 

 and loggerhead. They may occur in the same field, or be entirely 

 dissociated. But it is suggestive of the similarity of their nature 

 that both reached their fullest development in St. Kitts and 

 Nevis in the same season, that both ceased to be developed when 

 fine sunny weather set in, and that neither has since been noticed 

 to any significant extent. 



Rust. 



A species of rust fungus is common on the leaves of perennial 

 cottons throughout all the islands. The variety known as Nevis 

 Purple and some others are specially susceptible to it. Sea 

 Island is usually only attacked on old leaves toward the end of 

 the season, but earlier infestation occurs on unthrifty plants. 



The fungus in all cases appears to be Kuehneola Gossypii 

 (Lager.) Arth., first described as Ure.do Gossypii by Lagerheim, 

 in 1891, from specimens collected in Ecuador. It is recorded 

 from British Guiana, the Lesser Antilles, Cuba, Porto Rico, and 

 Florida. The uredospores commonly met with are borne mostly 

 on the underside of the leaves in numerous small round sori, 

 which are generally enclosed by a purple ring and marked on the 

 upper side of the leaf by a purple spot. 



Red Leaf Blight. 



Cotton grown in poor or deficient soil is liable to show a 

 special symptom of ill-health which is known as red leaf-blight or 

 as " rust." The latter name is unfortunate as the affection has 

 no relation with the actual rust fungus occurring on cotton. 

 The condition referred to is marked by a discoloration of the 

 leaves, which become conspicuously suffused with red or reddish 

 brown. It is commonly associated with poor growth but may 

 occur on large plants in the middle or later stages of their exis- 

 tence. The affected leaves tend to fall prematurely. 



In St. Vincent the affection is very common from an early 

 stage on the undersized plants produced by land inadequately 

 manured, especially on slopes subject to loss by washing. The 

 manurial experiments conducted in that island appear definite- 

 ly to connect the affection with shortage of potash, a conclusion 

 reached many years ago in connection with the closely com- 

 parable affection occurring in the United States, 



Yellow Leaf Blight. 



A condition which in its general characters resembles the 

 affection described under this name by G. F, Atkinson, and also 

 known in the United States as " mosaic disease," or in its later 



