16 



immediately. The trees are usually secured from a com- 

 mercial nursery, often from some neighbouring island 

 or from Florida. 



Modification No. 1 : Windbreaks. If was observed in 

 Porto Rico shortly after commercial planting commenced, 

 that trees protected from the wind grew much better 

 than those exposed, and sin-ae then, systems of wind pro- 

 tection for young groves have been tried out in various 

 places with excellent result. Where the land is covered 

 with thick forest, a successful method is to clear off 

 the native growth in strips 200 to 500 feet wide, leaving 

 uncleared strips 20 to 25 feet between. Such strips of 

 forest growth at right angles to the prevailing wind di- 

 rection is of great protection to the young citrus trees, 

 Many planters object to the system because the forest 

 trees take nourishment from the citrus trees, and the 

 wind belts serve as a harbour for insects, such as the 

 parasol ant. These objections are frequently very serious 

 and should of course be considered. A windbreak of large 

 trees always impoverishes the soil for some distance 

 away, but this can to some extent be prevented by deep 

 plowing and subsoil breaking in which way the roots are 

 cut below the feeding limit of young trees. If ants are 

 troublesome it may be necessary to clear off the under- 

 brush in the windbreaks, and keep the surface soil clean 

 until the nests can be destroyed. Where there are no 

 forest trees on the land or where there are but a few 

 scattered trees of no value for windbreaks it has been 

 found advisable to plant artificial windbreaks. This has 

 been done and is being done with more or less success 

 in different places, but usually not until the planter sees 

 the necessity of it. That is, after the young orange trees 



