CHAPTER VI. 



DISEASES OF THE DATE PALM. 

 Palm leaf Pustule. (Graphiola phcenicis Pait.) 



See illustrations Nos. 41 and 42 on pages I22a and 1226. 



92. This is a fungoid pest and is reported from North 

 America, parts of South America, Ceylon, Algeria, Egypt, 

 other parts of India and elsewhere. It is to be found among 

 the local date trees wherever they grow in the Punjab. In some 

 cases where the trees had a large number of old leaves on them, 

 I have seen it quite bad. In most of thes3 cases the younger 

 leaves a;e usually practically free of it. It has not yet been a 

 cause of trouble among our imported date trees and little attention 

 has been paid to it. 



The disease is often seen as small hard black-pustules scat- 

 tered over both the lower and upper surfaces of the leaflets 

 (see illustration No. 42, Fig. 3). They are often about J millimeter 

 in diameter ; about J of that in height, and the top has a depressed 

 yellowish centre. 



The mycelium (body of the fungus) is composed of hyphee 

 (thread-like filaments) which are hidden in the tissues of the leaf, 

 and absorb nourishment from the leaf cells. The black pustules 

 are developed from the mycelium. They burst the outer layers 

 of the leaf cells and appear on the surface of the leaf. These 

 pustules are the sporocarps (structures in which the spores are 

 developed) of the fungus. 



Inside the sporocarp is the spore forming tissue which gives 

 rise to vast numbers of pale yellow roundish spores about '003 mm. 

 in diameter and which eventually lie loose in the pustule. These 

 minute spores, in suitable conditions are capable of germination 

 and reproducing the disease. From the centre of the pustule 



