Conditions here blend very much into those of the Sacramento Valley
sections. Continuing south there are plantings around Acampo, Lodi,
Stockton, Linden, Ripon, Modesto and more scattered plantings farther up
the valley. The danger from spring frosts increases southward due to the
earlier blooming of the trees. In some of these sections, notably around
Ripon and Modesto, the excessive use of irrigation water for alfalfa and
other crops has resulted in a rise of the water table in many places
until it is within a foot or two of the surface during the summer months,
and in many other places comes to within four feet of the surface.
On the west side of the San Joaquin Valley the principal plantings have
been in eastern Contra Costa County. Most of these orchards are of old
trees, planted from 15 to 30 years ago. In order to obtain satisfactory
air and soil drainage the orchards were planted on the rolling hills,
the soil being nearly all blow-sand. Irrigation is too expensive to be
installed on most of this land, and the problem in that section is to
conserve moisture and at the same time hold the soil in place and prevent
it from being carried away by the wind.
[Illustration: Fig. 3.—Typical hillside orchard of Jordan almonds near
Los Gatos. Trees are variable in size, and some are missing. In the right
foreground is a typical spot of missing trees resulting from Oak fungus
infection.]