12 TBINIDAD AND TOBAGO BULLETIN. [XIX. 1. 



7. The first recognisable symptom is the presence on the leaves of 

 elongated spots and patches, often running out into streaks ; pale at first, 

 then red, and finally dry and brown. These spots follow the appearance 

 of the adult froghoppers and have been shown by Mr. Williams to appear 

 on leaves of healthy canes when froghoppers are caged upon them. 

 They are undoubtedly due to the feeding of the adults on the leaves and 

 their size suggests a locally toxic effect following the puncture, such as 

 is known to occur, with various species of bugs feeding on plant or 

 animal hosts. The spots do not begin to show plainly until more than a 

 week has passed from the first feeding of the froghoppers. The appear- 

 ance of the spots in quantity is followed by the general withering of the 

 leaves, the oldest first, until in severe infestations only the young leaves 

 in the centre of the shoot remain green and the infested area takes on a 

 general scorched appearance. Accounts agree that this condition may 

 be reached within two weeks of the first notable indications of its onset. 



8. Associated with the injury to the leaves and apparently consequent 

 upon it there is an equally definite condition produced in the stool as a 

 whole. When stripped of the clinging dry leaves the individual shoots 

 show, in different degrees according to their age, the effects of arrested 



• development and of the degeneration which ensues. In all respects 

 these effects are greater in severity in proportion to the youth of the 

 shoots. In a given case of first ratoons, for example, the gradations 

 were as follows : 



[a.) Well-developed stems (4-5 ft.) with arrested growth but no 

 degeneration. Green leaves reduced to a partly extended fan 

 at the extreme top, and these heavily spotted with red. 



Qj) Stems still of good length (3-4 ft.) but more slender and 

 unripened. Green leaves reduced to a few at the tip. 



(c.) Very pale stems, less than half an inch in diameter and about 

 two feet long, with only the central unexpanded leaves green. 

 Upper joints very tender, snapping readily just above the nodes. 



(fZ.) Similar stems 15-18 inches long, tapering very quickly at the 

 top ; leaves all withered ; tip of stem reddened and watery, 

 obviously degenerating. 



(e.) Similar stems about 9 inches long, iipper joints watery and 

 collapsed, rotting; basal joints still sound. 



(/.) Shoot bases from half an inch to 3 inches, quite dead. 



9. The condition as described represents effects of about medium 

 severity in respect of the attack and its duration. In the worst examples 

 the whole stool may be killed to the ground, or in a few cases killed 

 outright. From the account just given it will be seen that this result 

 can readily occur where no developed canes are present, a liability which 

 affords one reason why ill-grown ratoons are so subject to severe damage. 

 Where on the other hand the earlier shoots have formed canes with a 

 fair degree of ripeness, these usually, in such cases as have come under 

 my observation, survive even the worst infestations, and where the caneg 

 ■in general are well developed, as is commonly the case with plant canes 

 and may be the case under favourable conditions with i-atcons, the 

 damage consequent on a froghopper infestation will commonly be 



