Vol. V. No. 120. 



THE AGRICULTURAL NEWS. 



379 



PREVENTION OP PLANT DISEASES BY 

 PROTECTIVE JUNGLE BELTS. 



In his report on the Department of Agriculture in 

 the Federated Malay States for 1905, the Director 

 (Mr. J. B. Carruthers) makes the following interesting 

 reference to the use of protective jungle belts as 

 a pi-eventive of plant diseases : — 



The prevention of the spread of disease in large areas of 

 one species of cultivation is of first importance, and at the 

 outset of the planting up of rubber in the Federated Malay 

 States steps must be taken to guard, as far as can be done, by 

 planting or leaving jungle and thus making barriers, against the 

 too easy distribution of parasitic insects and of the spores of 

 fungi which attack living plants. 



That each estate should itself plant protective belts is, 

 when laige 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 an}' rate protected 

 for a time, so that 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 2 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 in 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 at once to reserve the belt, 

 and I selected this area chiefly because it included a series of 

 bukits — i.e., small hills — and thus added 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 continua- 

 tion eastward of the barrier. 1 hope to be able to record in 

 future reports the continuation of this policy in other states, 

 where immediate action is not so necessary, as comparatively 

 small areas have as yet been alienated for rubber. 



The value of such protective belts in tropical countries 

 is not sufficiently recognized. 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 ilalay 

 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 

 Malay 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 in the planting 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 atiy bushes in 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 wind- 

 borne spores. Other proof of the eificacy of such protective 



belts can be got from observations of tea, coS'ee, 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 strij) of jungle at the brow of 

 a hill, a field was badly blighted with leaf disease (Pestaloizia 

 guepini, Desm.). A road 2.5 feet wide had been cut through 

 the jungle, and on the leeward side was a field of tea, which, 

 during the south-west monsoon, when the wind blew from the 

 unattached 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 shovif 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 such 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 accptired a liking 

 for jungle foliage, the interposition of a sufficiently thick belt 

 would eff'ectively prevent their reaching rubber or other 

 cultivations on the far side. 



HOW TO GROW CHRYSANTHEMUMS IN 

 THE WEST INDIES. 



A correspondent in St. Kitt'.s has forwarded the 

 following notes on growing show chrysanthemums : — 



Young plants can be obtained from growers in England 

 or America, about August. The growers usually pack them 

 in the same wa,y as for transport in temperate regions. This 

 gives very bad results, all leaves and all young stems arriving 

 in a rotten and mouldy condition. The growers should be 

 instructed to pack as follows : Choose young plants which 

 have formed woody stems; cut off nearly all the leaves and 

 prune all the soft stems ; wrap a very little wet sphagnum 

 round the roots, and envelop the whole in about five loose 

 folds of paper, some of which may be glazed, but not waxed. 

 Do not use any box, and a paraffined box is the worst of all. 

 If a box must be used, trust to paper wrappings for keeping 

 moist, and cut the box full of holes. 



When the young plants arrive, wash them well, cut off 

 all rotten parts, and plant them in pots. It is best to put 

 them first in small (thumb) pots in sandy soil, plunged in 

 moist sand in a box. They .should be in full sun, or 

 protected by a lattice only. When they have produced new 

 roots and leaves they may be transferred to 4- or 6- inch pots. 

 These latter pots .should have broken crocks covered with 

 cocoa-nut fibre at the bottom, and the soil should be one-third 

 sand, one-third loam, one-third leaf-mould thoroughly mixed, 

 with a spoonful of basic slag (for volcanic soil) or superphos- 

 phate (for lime soils), and a spoonful of sulphate of potash. 

 When the plant is well established a small pinch of nitre 

 must be put on the top every few days, according to the 

 needs of the plant. When the plant is established, it must 

 be in full sunshine or under a lath lattice of alternate laths 

 and spaces. The first buds are usually single (crown buds) 

 and are generally best nipped off. When a cluster of buds 

 appears, nip off all but the centre one (terminal). Do not 

 leave more than two buds on the plant. Never water until 

 the pot is fairly dry and then fill it to the brim. The pots 

 are best plunged in the earth. When the one or two choice 

 blossoms have appeared let the plant grow at random to 

 provide cuttings. The cuttings root easily in fresh moist 

 sand, and, like all cuttings, their growth is rendered more 

 certain by dipping the ends in strong Bordeaux mixture. 



