When to Fertilize. 155 
properties, as is shown in the chapter on the fruit soils of Califor- 
nia. But certain of these soils are already showing the need of 
refreshment, and intelligent growers are quick to minister to 
the lands which are giving them such generous returns, as they 
can well afford to do. Present progress in the use of fertilizers 
rests upon the clearly demonstrated hunger of the orange tree. 
An active fertilizer trade has proceeded from a center in Los 
Angeles and asserted itself all through the southern citrus re- 
gions. More recently growers of other fruit and nut-bearing. 
trees have seen that even the deepest and richest soils could not 
honor unlimited drafts upon their fertility, and money expended 
for fertilizers has continually increased. Recently, too, fruit 
growers in the upper regions of the State have learned the need 
and the profit in fertilizing, and in the future natural manurial 
supplies will be carefully husbanded and commercial fertilizers 
will be profitably used. 
WHEN IS FERTILIZATION NECESSARY? 
Though the use of fertilizers by our fruit growers is begin- 
ning, it should be plainly stated that at present, except perhaps 
with citrus fruit trees, or the oldest orchards of other fruits, it 
is not the rule that such applications are necessary. There is 
reason to believe that we have some soils which are really too 
rich for fruit. There is sometimes an overrank growth of wood, 
which delays or prevents the formation of fruit buds, and there 
is a marvelous development of fruit which is inconsistent with. 
the highest quality. For this reason the grower should not: 
conclude, from the foregoing general remarks concerning the 
need of fertilization in California, that he must manure his soil 
whether it. needs it or not. Especially is this the case with 
young trees, in which the wood growth is easily overstimulated. 
As with irrigation, so in fertilization; the tree or vine itself will 
give the observing grower hints as to its needs, and if the growth 
of wood and color of foliage are such as obviously indicate 
health and vigor, it may be concluded that the plant needs 
nothing but good cultivation and intelligent pruning. 
Usually cases of overrich ground will cure themselves as 
the trees attain size and full bearing, and it is then that fertiliza- 
tion may be necessary. When the tree or vine which has been 
properly pruned and cultivated is not able to mature a good 
weight of well-developed fruit, and make a satisfactory wood 
growth, usually at the same time showing some degree of dis- 
tress by the color of its foliage, it needs help; and if the grower 
is sure that the trouble is not from lack of moisture in the soil, 
he ‘should bestir himself in the manuring of his orchard or vine- 
yard. In examining the soil for moisture, one should dig 
