28 TROPICAL AGRICULTURE 



lie attention consists in the artificial propagation and distribu- 

 tion of insect parasites. Perhaps the best results with insect 

 parasites have been obtained in Hawaii, where by this means 

 complete control was secured over the sugar-cane leaf-hopper 

 and the sugar-cane borer. Recently, moreover, the insect para- 

 sites imported for the control of the Mediterranean fruit fly 

 appear to be giving promise of efficient help. 



Similarly with plant diseases, the favorable conditions for 

 fungous and bacterial growth furnished by continuous warm 

 weather and moist atmosphere make these enemies of crop 

 production more serious at times perhaps than is ever the case 

 in temperate climates. Certain notorious diseases of plants 

 have made the cultivation of certain crops impossible in some 

 localities. Thus, we have the well known case of the coffee 

 leaf blight Hemileia vastatrix which totally destroyed the 

 coffee industry of Ceylon and parts of India, forcing the coffee 

 growers into the production of tea. In parts of Central Amer- 

 ica and the north coast of South America, the Panama disease 

 of bananas has caused such ravages among susceptible varie- 

 ties of bananas in certain localities that the industry had to 

 be abandoned. In a few instances, resort was had to the 

 Chinese banana, which is not susceptible to the disease. Not- 

 withstanding the great economic disturbances caused by the 

 prevalence of such diseases, the abandonment of one crop 

 and adaptation of another crop were accomplished without 

 staggering financial loss and in the end to the benefit of the 

 planters concerned. On the whole, insect pests and plant 

 diseases are no more serious obstacles to agricultural produc- 

 tion and development in the Tropics than in the temperate 

 climate. 



