microns ; conidiophores colourless, at least longer than the 

 conidium, 12-28 by 5 microns; setae single or in tufts, 

 blackish-brown at the base, almost hyaline at the apex, 

 septate. 



SOUTHWORTH : Journ. of Mycology, Vol. VI., p. 100. 



ATKINSON : Journ. of Mycology, Vol. VI., p. 173. 



LEWTON-BRAIN : West Ind. Bull., Vol. IV., p. 265. 



COLLETOTRICHUM GLEOSPORIOIDES, PENZ. 

 (Leaf spot, wither tip, etc., of Citrus spp.) 



The species of Citrus which are affected by this fungus 

 are the lemon (Citrus limonuni), the orange (Citrus auran- 

 tium), the lime (Citrus acidd), and the pomelo (Citrus 

 Paradisi}. The fungus has been reported to occur in 

 Florida, Jamaica, Cuba, South America, Malta, Italy and 

 Australia, and has, therefore, a wide area of geographical 

 distribution. 



The disease commences either at the tip or edge of the 

 leaf, more rarely it starts at the mid-rib or at an inner 

 portion. The parts attacked become light green in colour, 

 and the colour changes later to dark brown. The acervuli 

 of the fungus are formed on the diseased parts, and are 

 at first brown in colour, becoming later dark brown or 

 even black. In this form the disease is known as " leaf 

 spot." 



From the leaves the disease may spread to the younger 

 shoots. When a shoot is attacked it dies back for a certain 

 distance from the tip, or it may in some cases die back as 

 far as the trunk. In the former instance a bud situated 

 below the dead part usually develops, but if the disease 

 is not treated the second sprout so formed withers also. 

 In this form the disease is known as " wither tip." 



" Leaf-spot " and " wither-tip " are characteristic patho- 

 logical effects caused by the fungus, and are produced 

 when the lemon, orange and pomelo are attacked. In the 

 case of the lime, however, " anthracnose " of the young 

 shoots usually occurs. In it the upper portion of a shoot 

 is cut off and either hangs down or falls away ; the effect 

 is similar to that caused by a biting insect. 



In the lime the blossoms and young fruit are frequently 

 attacked by the fungus. Older fruits may be attacked, 

 but those which are more than half mature are seldom 



49 



