Miscellaneous. 



108 



of parasitic insects and of the spores of fungi which attack living plants. That each 

 estate should itself plant protective belts is, when large yields per acre are so much 

 desired, perhaps too much to expect. Districts, however, can be to some extent 

 divided off. so that the outbreak of disease in one locality may be confined within 

 limits, and plantations in other parts may either be preserved from the evil or at any 

 rate protected for a time, so tint the preparations may be made to prevent or 

 combat the attack on its first appearance. I selected an area of about 16 miles long 

 by two wide running from the Buloh river in a south-east direction to the Klang 

 river and adjoining the Sungei Buloh forest reserve. The direction of the prevalent 

 winds is not sufficiently constant iu Selangor to make the position of the protective 

 belt in regard to points of the compass important. So much land had already been 

 taken in Klang and Kuala Selangor districts that it was important to at once 

 reserve the belt, and I selected this area chiefly because it included a series of 

 bukits— i.e., small hills— and thus add to the height of the barrier, also because it 

 included the water catchment area for Klang, which will remain in jungle, and 

 adjoined the large forest reserve of Sungei Buloh, which thus forms a continuation 

 eastward of the barrier. I hope to be able to record in future reports the continu- 

 ation of this policy in other States, where immediate action is not so necessary as 

 comparatively small areas have as yet been alieuated for rubber. The value of such 

 protective belts in tropical countries is not sufficiently recognised. In temperate 

 climates the spread of fungus and insect pests is checked by the advent of winter, 

 and even in the warmer months the rate of increase of diseases due to fungus or 

 insect attack is much slower than in tropical countries. In a climate like the Malay 

 Peninsula the conditions for the spread of fungi are almost perfect. Moisture and 

 heat are the essential factors necessary to the germination and growth of spores of 

 fungi, and in Malaya these conditions are present practically all the year round. 

 During the last six years in Ceylon I have been carrying out experiments as to the 

 wind distribution of spores, and had at various elevations and aspects iu the plant- 

 ing districts of that island erected experimental " tabernacles "— i.e., jute hessian 

 screens enclosing a space 48 feet by 8 feet broad 9 feet high and open to the sky. 

 These screens were placed at right angles to the prevalent winds and erected on tea 

 fields just after the bushes had been pruned, and before any leaves were produced on 

 any bushes iu the field. In Ceylon the winds are approximately north-west and 

 south-east, respectively, during half the year. The appearance of the leaf spot 

 fungi on the leaves of bushes inside the tabernacle and on the windward and leeward 

 sides, respectively, were carefully observed. These experiments showed clearly the 

 value of a mechanical protection from the attacks of Avind-borne spores. Other proof 

 of the efficacy of such protective belts can be got from observations of tea, coffee and 

 other crops near to jungle. A case clearly demonstrating this point was given in my 

 annual report in Ceylon for 1901. On the windward side of a narrow strip of 

 jungle at the brow of a hill a field was badly blighted with leaf disease 

 (Pestalozzia guepini Desrn). A road 25 feet wide had been cut through the jungle, 

 and on the leeward side was a field of tea which, during the south-west mon- 

 soon when the wind blew from the unattacked to the blighted field, showed 

 no sign of disease. A short time after the north-east monsoon began to blow 

 the healthy field began to show signs of leaf blight, but only on the bushes 

 near the road through the jungle. On burning a bonfire on the windward side 

 of the jungle the smoke covered, during the half hour it was watched, practically 

 the whole area that contained bushes attacked by leaf disease. 



That sucii a protective jungle belt is a certain safeguard is not claimed, 

 but that it must prevent a large amount of infection is certain. To insects 

 the barrier of jungle would be equally deterrent, and unless the insects acquired 

 a liking for jungle foliage the interposition of a sufficiently thick belt would 

 effectively prevent their reaching rubber or other cultivations on the far side. 



