RUBBER PLANTING 179 



knowledge of the general principles of plant sanitation 

 is even more important than a knowledge of special 

 diseases. 



Wind. 



Perhaps the most serious of all pests which affect 

 the health of rubber plantations is an inanimate one, 

 namely wind. In regions which are severely wind-swept 

 it is useless to attempt the growth of Hevea rubber. In 

 less exposed situations the force of the wind may be 

 broken by leaving belts of jungle when the original 

 clearing is carried out, or by planting rows of hardy and 

 quick-growing trees as special wind-breaks. The idea 

 of jungle belts has frequently been suggested as a 

 means of checking the spread of fungus diseases, but 

 it appears to have been very seldom carried into effect, 

 the planter preferring to occupy the whole space at his 

 disposal with his own proper crop. Such belts more- 

 over possess this serious disadvantage; that if they are 

 wide enough to prevent the passage of wind-borne 

 fungus spores they are also large enough to afford an 

 excellent harbourage for weeds and for many of the 

 vertebrate enemies mentioned in the next paragraph. 



Animals. 



Among the larger animal pests of rubber plantations 

 are elephants, deer, cattle, pigs, monkeys and porcupines. 

 All these animals are liable to effect widespread destruc- 

 tion in young clearings, and porcupines may even cause 



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