32 COTTON 



plants naturally die off during the unfavourable 

 season and annual planting thus becomes inevitable. 



Considerable advantages are gained by growing 

 cotton as an annual. The crop only occupies the 

 ground for six or seven months and can therefore be 

 readily alternated with other crops and a system of 

 rotation established to prevent deterioration of the 

 soil. The early harvesting of the cotton is, moreover, 

 of great importance in checking the spread of pests 

 and diseases. The ground ought to be thoroughly 

 cleared after each crop in order to reduce the risk of 

 disease as far as possible. 



At one time it was the custom in the West Indies 

 and other countries to grow perennial stocks and to 

 ratoon the plants or prune them heavily at the end of 

 the season. 



In connection with the growth of perennial cotton, 

 reference may be made to certain interesting experi- 

 ments which are being conducted in Hawaii on the 

 propagation of the plant by cuttings and also by the 

 method of budding. These experiments have already 

 given indications of success. 



In some countries, particularly Brazil and Peru, 

 perennial tree-cottons are still grown on a commercial 

 scale. Some of these forms are referred to on pages 69-70. 



DISEASES OF THE COTTON PLANT 



The cotton plant is liable to be affected by numerous 

 diseases. These may be divided into three classes : 

 (i) those which are due to physiological causes, such 

 as deficiencies in certain kinds of nutriment and the 

 consequent weakening of the plant ; (2) diseases 

 caused by the attack of fungoid pests ; and (3) dis- 

 eases due to the attack of insect pests. 



It is not possible in the present work to deal fully 

 with this subject, but reference will be made to the 

 most important of the diseases, and an indication will 

 be given of the best means of combating them. 



Diseases due to Physiological Causes. Among these may 

 be mentioned mosaic disease or yellow leaf blight, red 

 leaf blight, the shedding of bolls, and angular leaf spot. 



