26 TROPICAL AGRICULTURE 



ironwood or Australian pine (Casuarina equisetifolia) does 

 excellent service as a windbreak in almost any situation. It 

 will thrive in brackish or actual salt water at sea level, grows 

 well where the rainfall is relatively heavy, and is also ex- 

 tremely drought resistant. After becoming well established, 

 it will readily withstand droughts in which all species of euca- 

 lyptus die out. Where there is a reasonable amount of rain- 

 fall, eucalyptus is an excellent tree for use as a windbreak. 

 Perhaps Eucalyptus robusta is the most satisfactory for this 

 purpose. It may be planted in three rows of trees alternating 

 in position so as to make a dense windbreak zone. Under 

 favorable conditions they may be expected to reach a height of 

 IS to 20 feet in two years. 



The number of trees used for windbreaks is legion and in 

 different tropical countries the choice of planters for wind- 

 break trees naturally varies according to their experience in 

 their own locality. In all tropical countries lying within the 

 trade-wind belt it is well to plant rows of trees adapted for 

 windbreaks at suitable intervals across the fields of arable land. 

 Windbreaks are useful and almost necessary in the case of the 

 more tender and sensitive tropical plants, but of course are not 

 required on plantations of sugar cane and pineapples. 



On account of the fact that weeds grow the year round in 

 tropical countries, certain special methods of weeding have 

 been adopted in order to reduce the expense of the constant 

 cultivation for the destruction of weeds. In the case of many 

 tropical crops, such as sugar cane, coffee, bananas, etc., the crop 

 itself even before it reaches full size so completely shades the 

 ground as to destroy most of the weeds between the rows. 

 During the early growth of these crops, however, attention 

 must be given to the destruction of the weeds. In some cases 

 the use of leguminous cover crops has given excellent and 

 economic results in weed destruction. In Hawaii, Crotalaria 

 has been used for this purpose with good results. The cover 

 crop must be a quick and vigorous grower in order to rise above 



