CHAPTER VIII 

 PESTS AND DISEASES 



IN all tropical and subtropical countries, it is as necessary 

 to be prepared for combating insect pests and fungous 

 diseases of plants as to be prepared to till the soil and 

 fertilize the plants. 



Insects and fungi are as resistant to cold as are plants 

 which are cultivated, and these multiply with very great 

 rapidity and are present in very large quantities through- 

 out all regions where vegetable crops are grown. There 

 is no escaping these enemies, and hence they must be 

 combated by the best known methods. 



Considerable attention has already been paid to de- 

 veloping varieties that are resistant to certain diseases 

 in certain localities. It is not probable, however, that this 

 line of investigation can be carried speedily to the point 

 where the plants will be resistant to all of the numerous 

 diseases. The moment we have plants that are resistant 

 to the wilts diseases, for example, we find that they are 

 still subject to an attack from other enemies. 



It is frequently stated that by proper cultivation and 

 fertilization plants will be able to throw off diseases and 

 insects. This is quite incorrect; a plant vigorous and 

 healthy in every respect, is so simply because it has not 

 been attacked or had to endure the disadvantageous con- 

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