REQUIREMENTS OF CITRUS FRUITS 363 



have appeared in some groves and have been accounted for by digging 

 to find the roots bedded in mud and slush. All plantings over clay sub- 

 soils should be guarded against this danger. Digging deep holes and 

 filling them with good soil is setting a trap for the future failure of the 

 tree unless the deep hole is properly drained by the nature of the sub- 

 soil or by artificial provision. On the other hand, planting over a 

 gravelly sub-soil is often disappointing, because the water passes 

 through the sub-soil as through a sieve and the tree shows distress 

 although generous amounts are applied to the surface. Wide observa- 

 tion through the State teaches that such warnings are needed by the 

 unwary. There has also been injury to the trees from planting over 

 sub-soils carrying excess of lime. 



Local temperature conditions even in sections generally suited to 

 orange culture should be carefully ascertained. Frosty places must be 

 avoided. A few feet difference in elevation may change profit to loss, 

 but one must not therefore draw the hasty conclusion that all small 

 elevations are favorable. The experience of the last few years shows 

 that nothing is, on the whole, more dangerous than the warm bottom 

 land in a small elevated valley which seems naturally protected on all 

 sides. There are many such places which are far more treacherous than 

 the uplands of the broad valleys, which may be considerably lower. 

 The benches around the sides of the small valley may be safe and the 

 bottom of the same valley dangerous because there is no adequate 

 outflow for cold air to the large valley below. Look out for small 

 valleys which have divides of crumpled hills where they debouch into 

 the main valley. Cold air can be dammed and held back ; consequently 

 the low land of a small valley may be worse than lower land in the main 

 valley, because in the latter there are air currents which prevent 

 accumulation of cold air in particular places. These air movements 

 make some plantings on the upper plains of the main valley safe, though 

 the whole region may seem to the eye rather flat and low, but, of course, 

 broad sinks of the main valley may also be dangerous. Too great 

 elevations are to be guarded against. Where one approaches the 

 reach-down of mountain temperatures and loses the warming influences 

 of the valley mesas, the danger line is at hand. 



An ample water supply is essential. Small waterings which may 

 bring satisfactory growth to a young tree are no measure of the needs 

 of a bearing tree. The orange is using water all the year, as discussed 

 in Chapter XV. Its crop requires nearly a year to reach maturity. 

 Both in leaf growth and fruit growth it nearly doubles the activity 

 of the deciduous tree and all the time it is pumping water with its 

 roots and pouring forth water into the air through its exposed surfaces. 

 No investment in orange planting can be profitable without assurance 

 of adequate water supply. 



PROPAGATION OF THE ORANGE 



The orange is grown from cuttings, layers and seeds. Growth from 

 the seeds is the method almost exclusively followed, and by far the best, 

 but the others will be mentioned briefly. 



