.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.