OF THE 



DEPAHTISIENT OF AGmiOULTTTJaE 

 Trinidad, and Tobag-o. 



Part 1.] [Vol. XVIII. 



LIMES 



THE WITHER-TIP OF LIMES. 



Bi' James Birch Borer, 

 Mycologist, Board of Agriculture. 



With One Plate. 



During July and August, 1918 there was a severe outbreak of a 

 disease of lime trees throughout the colony, practically all districts 

 being equally affected. Specimens were received from a large number 

 of different estates, and all showed " wither-tip " in its characteristic 

 form. This is one of the commonest and most destructive diseases 

 of limes, though heretofore, it has not been very prevalent in Trinidad. 

 It is due to the fungus known as Qloesporium limetticolum, Clausen. 

 The fungus is able to attack the young growth of lime plants of all 

 ages ; in fact, at the St. Clair Experiment Station it has caused the 

 death of a great many nursery plants of from six inches to a foot high, 

 during the past two years, (i) 



APPEAEANCE OF THE DISEASE. 



The attacks of the fungus generally show on the tips and edges of 

 the very young leaves, but they affect also the leaf stalk, at the point 

 where the leaf joins the stem, or any point in the very young shoots. 

 The first sign of infection is indicated by a somewhat' water-soaked 

 appearance until the young leaves and tip of the shoot are entirely 

 destroyed. If the weather is not so damp, the water-soaked appearance 

 is not so pronounced, but the attacked part is light green in colour at 

 first, and then become brown. In all cases, the affected shoots wither 

 up, thus giving the popular name of the disease. When the larger 

 young leaves are affected they often become carled and distorted and 

 the infected areas drop out or become cracked, so that the leaf is 

 punctured with holes. Only young growing leaves and the young shoots 

 apparently can be attacked by the fungus; leaves and shoots that 

 have become hardened and matured are quite immune to the 

 disease. 



(1.) This disease musb not be confused with the " Damping-off " disease which 

 is very severe on seedlings when the}' are from one to three inches high, and which 

 has already been described in the Proceedings of the Agricultural Society, KV, 1915, 

 14-15, " "Wither-tip " generally attacks the plants when they are a little older. 



