Plant Sanitation. 



30 



[Jan. 1907. 



Specimens of vine leaves, badly infested by a small species of Thrips have 

 been received from Colombo. Flowers of sulphur will be found a useful remedy in 

 such cases. It should be dusted freely upon the plants in such a manner that it will 

 reach the undersurface of the leaves where the insects are mostly congregated. 



The ' Arrakkoddyan worm ' {Spodoptera mauritia) was reported to be damag- 

 ing paddy crops in the Walawe district in December. A circular, giving full 

 instructions for the treatment of this pesfc, was issued by the Ceylon Agricultural 

 Society early in 1905, and should be distributed to cultivators at the earliest report of 

 the appearance of the caterpillars. The success of the treatment depends upon its 

 prompt application. 



A Disease of Palmyra Palms. 



In 1901 the outbreak of a serious disease in the Palmyra Palms of the 

 Godavari delta was reported. In 1905 coconut palms were also attacked, and in 

 consequence, the disease was especially investigated by Ur. Butler, Mycologist 

 to the Government of India, who has recently written accounts of it in the Agri- 

 cultural Journal of India (October, 1906) and in a report to the Government of Madras. 



The disease is said to have been noticed as far back as 1897, but it has 

 only extended rapidly within the last two or three years. It may be said in a 

 general way that most of the villages within a radius of fourteen miles from its 

 supposed starting point are affected. It is estimated that about ten per cent, 

 of the palmyra palms in this area have been killed. The most serious feature is 

 the fact that coconut palms are undoubtedly subject to infection, though they 

 are never, in any of the localities visited, so frequently attacked as the palmyra. 



The symptoms can be recognised fairly easily, the earliest sign being .an 

 alteration in colour of one of the leaves, usually one of those recently expanded, 

 towards the centre of the head. This leaf turns white and soon afterwards 

 commences to wither. Other leaves are attacked in succession, the heart of the 

 bud is reached, and the whole top is withered and falls off, the last stage often 

 being reached only after a considerable time. In coconut palms, the same generas 

 course is followed, but here if the nuts have been formed before the attack becomes 

 severe, they are often dropped prematurely. The Ceylon "Bud Rot" appears 

 to differ in that the unexpanded leaf gives the earliest indication, and withers 

 Avithout turning white. 



The expanded parts of the leaves are unaltered and apparently healthy 

 until withering sets in, but on the leaf-sheaths there occur irregular sunken-in 

 spots. In the earlier stages they are white, later on becoming brown, but always 

 sunken and usually with somewhat raised edges. They may be traced in from 

 the outer sheaths, sometimes passing through every succeeding layer until the 

 bud is reached. The earlier spots are dry, and either show no sign of a foreign 

 organism on their surface, or are covered with a whitish felt of fungus giowth. 

 Very soon a wet rot follows, and the bud becomes a foul smelling mass of putre- 

 faction. 



The fungus is a species of Pylhium. Fungi of this class produce spores 

 of two kinds, one of which requires to fall into water as it produces motile 

 zoospores. The amount of water required however is very small. " An organism 

 of this type would account for the slow extension of the disease. Its spores are 

 produced chiefly in the inner layers of the bud, and then not often in great 

 quantities, while being comparatively large and requiring to fall into water in 



