CITRUS CULTURE IN HAWAII 



5 



very humid localities where the rainfall is 100 inches or more 

 per year, a lichen (Physcia steilaris) may be found growing upon 

 the trunk and the branches of citrus trees, and the juice of the 

 fruit becomes insipid. In hot, dry localities where irrigation is 

 necessary, transpiration is rapid, the lichen does not appear, and 

 the fruit contains less juice but it is of better flavor. Under 

 such conditions the amount of moisture consumed still remains 

 high. 



The moisture requirements of a citrus orchard are best 

 learned by studying the condition of the trees. They should 

 never be allowed to show symptoms of suffering, such as drooping 

 leaves. In such a condition both tree and fruit are likely to 

 be injured. Citrus will thrive on many kinds of soils, but the 

 soil should be at least 4 or 5 feet deep, rich, abundantly moist, 

 and well drained. . Extremely heavy or very loose soils are not 

 suitable for citrus culture. 



In windy localities young citrus trees should be given tem- 

 porary protection during the winter. This may be supplied in 

 the form of a piece of burlap about a yard square tacked to three 

 upright stakes on the windward side of the tree. As a protec- 

 tion against the heavy winds that come from the northeast and 

 occasionally from the south, large permanent windbreaks should 

 be grown where needed. Such rapidly-growing, wind-resistant 

 trees as the eucalyptus (Eucalyptus robusta), Australian oak 

 (Grevillea robusta), mango (Mangifera indica), and ironwood, 

 or so-called Australian pine {Casuarina equiseti folia) will serve 

 the purpose. They may be set alternately in three rows 10 feet 

 apart, and the same distance apart in the row. The eucalyptus 

 should be set nearest to the prevailing wind; and the row ad- 

 joining the orchard should consist of ironwood and mango trees 

 set alternately in the row; and the central row should be made 

 up entirely of the grevillea trees. The mango has a strong, dense 

 top and, if properly grafted, has the additional value of pro- 

 ducing fruit in season. When the mango trees begin to crowd, 

 some of the grevillea and possibly some of the ironwood trees 

 may be removed. The horizontal roots of these trees can be 

 prevented from encroaching on the citrus area by maintaining 

 a narrow ditch 3 or 4 feet in depth about 4 feet from the row 

 of ironwood trees. Preventing the spread of roots on one side 

 does not have any serious effect upon the ironwood trees. The 

 ditch should be dug out every other year, left open for a few 

 months, and then refilled. 



Planting 



The most suitable time for setting young citrus trees is in 

 the early spring, but the late spring may be preferred in cool 

 localities, particularly where the rainy season is in the summer. 

 At some of the lower elevations, where the summers are very 

 hot and dry* citrus trees are not set until the fall. The orchard 

 site should be cleared and the land thoroughly and deeply 

 plowed. The surface should be cleared of all vegetation, stones, 



