THIRTY-THIRD BIENNIAL SESSION 
53 
our fruits as long as the moisture supply is not excessive. While some 
chemical changes take place in the apple, as noted in the apple investigations 
that our chemists have made in co-operation with us up to the present time, 
they do not warrant us in drawing definite conclusions. 
Then there is the relation of adequate moisture supply to the fertility 
of the soil. There is no doubt but that excessive irrigation washes out 
much of the plant food from the soil, but it is also true that with plenty of 
moisture we can germinate our cover crop seed early in the season and get 
a much better growth than we could without the water. 
The possibility of irrigating is revolutionizing orchard soil management 
on the Pacific Coast. It would now appear that at no distant date there 
will be very few clean tillage orchards on the Pacific Coast. With irrigation 
we are able to grow leguminous crops, such as alfalfa and clover, among 
the trees. The results we have obtained from the first few years of the 
system are very gratifying. The trees are growing well, are of better vigor, 
and yield better. It is a cheaper system of handling the soil. We avoid 
excessive warm temperature in the soil and tend to keep the condition of 
the soil as regards moisture and temperature much more uniform. All these 
influences undoubtedly have an effect on the vigor and production of the 
trees. From an economic point of view it is going to mean much to the 
irrigated fruit grower. It is going to mean that he can raise enough forage 
crops for his horses and cows, and while he may have to supply fertilizers 
in later years to replace food lost, at the same time he is reaping at present 
the benefits which he could not otherwise secure, and at a time when they 
are necessary to him. 
Then there is the relation of inter-cropping. It is only in orchards in 
which an abundance of moisture supply is available, either through copious 
rains or by means of irrigation, that one can successfully inter-crop. Straw- 
berries and vegetable crops of various kinds and certain forage crops are 
raised satisfactorily among young trees. In many of our western valleys, 
the strawberry has been the pioneer crop and has paid the running expenses 
of the family while they were waiting for the trees to come into bearing. 
It is interesting to note the relation of the moisture to the tree itself. 
Of course you all know that when a tree suffers from lack of moisture its 
vigor is affected; it makes a feeble wood growth, and the foliage is yellow 
and drops prematurely. With an abundant moisture supply which th© irrigator 
can always depend on he can produce a better wood growth, produce stronger 
buds, and the foliage is richer and of a better color. True it is, if he is not 
careful he can carry this to extremes especially with young trees, and throw 
them into fall and winter in a soft and unhardened condition. With old 
trees there is little danger of this. 
In short, irrigation is a powerful factor in American fruit production 
and is opening to horticulturists an ever widening and fascinating field for 
investigation. It is full of problems and the American Pomological Society 
should be keenly interested in the questions confronting the fruit growers 
on the Pacific Coast. 
I will now have a few pictures thrown on the screen that will illustrate 
some of the phases of the irrigation question. 
