.930] Prac CurTure IN CALIFORNIA
37
Methods of Irrigation.—There are three common methods of irri-
gating known as check (basin), furrow, and contour.” With the
basin or check system the soil is ridged into low levees by means of a
disk or ridger forming basins, each having one or more trees. Water
is allowed to flow from one check to the next, by cutting the levee
when the upper check is filled. A nearly equal quantity of water is
thus supplied to each tree (fig. 9).
The furrow system is another means of irrigating. It is adapted
to the use of small heads of water. Furrows may be used on gradual
to somewhat steep slopes. The method works better if the land is
graded before the trees are planted. Less labor is involved in irrigat-
ing by furrows than with the basin or check system. The objection to
the furrow system is that water may not be uniformly distributed
through the soil and it is nearly impossible to wet the entire soil mass.
The contour method of irrigation is particularly adapted to small
heads of water and steep grades. but a modification is also used on
fairly level slopes.
Drainage.'*—Excessive use of irrigation water should be avoided.
The judicious use of water is an important means of checking the rise
of ground water and the consequent alkali injury. Ditches should be
provided to take care of the runoff and to prevent standing water.
The practical way to lower the water table is to install a drainage
system of tile or ditches. Drainage alone, however, will not satis-
factorily correct an alkali condition.'®
PEACH DISEASES AND THEIR CONTROL
Common diseases occuring in California peach orchards may be
divided into three classes, diseases resulting from: (1) bacteria, (2)
fungi, and (3) diseases not caused bv organisms. but attributed to
functional disorders.
Symptoms of Diseases—Diseases usually have characteristic symp-
toms. In some cases the same symptom may indicate any one of
several diseases or even possibly an insect pest, as, for example, the
presence of gum. It is advisable for the peach grower to be familiar
with the characteristics of the more important diseases so as to be
able to recognize them if they appear. and to apply a remedy if
feasible.
17 Huberty, M. R. and J. B. Brown. Irrigation of orchards by contour furrows.
California Agr. Ext. Cir. 16:1-16. 1928.
18 Weir, W. W. Drainage on the farm. California Agr. Bxp. Sta. Cir. 304:1-30.
2 Kelley, W. P. and E. E. Thomas. Reclamation of the Fresno type of black:
alkali soil. California Agr. Exp. Sta. Bul. 455:1-37. 1928.
