California Agriculture, February 1967
Volume 21, Number 2
Air view of Imperial Valley Field Station, site of two irrigation experiments reported in this edition.
A comparison of deep and shallow drain tile for reduction of soil salinity in Imperial Valley
by F. E. Robinson , J. N. Luthin
In these tests, more salt was removed per unit of time by constant flooding than with intermittent flooding — indicating this treatment would be preferred where land values are higher or water is inexpensive. However, intermittent irrigation removed more salt per unit of water applied—indicating that where water is expensive, or land values low, this would be the better treatment. The shallow tile increased the rate of salt removal from the first and fourth foot of soil in the intermittent treatment, and for all depths except the fourth foot, under the constant flooding treatment. For soils having a less permeable layer at shallow depths, the use of shallow drain lines in addition to deep lines will increase the leaching of the soil and will help salinity control.
Chemical growth control of Chinese elm trees
by W. D. Hamilton , W.B. Davis
A 2500 ppm MH30T spray applied in July appeared to give satisfactory growth control in Chinese elms the following year, at least up to the later part of June—and with less detrimental effects to the trees than other sprays tried. Better results in the use of MHBOT sprays on Chinese elms may come from raising the height of branching to 8 to 10 ft above the ground, and pruning the trees a month before applying the growth-retardant spray.
An evaluation of sprinkler irrigation for Imperial Valley
by F. E. Robinson , O. D. McCoy , G. F. Worker
Sprinkler irrigation reduced surface salt accumulation, increased water use efficiency, and cooled the soil surface more effectively than conventional furrow irrigation in recent tests. No detrimental effects were observed on lettuce, cabbage, carrots, onions or sugar beet seedlings from sprinkler application of Colorado River water. Emergence of seedlings was significantly higher with cabbage, sugar beets, carrots, and onions—and in some cases with lettuc—when sprinkled, as compared with furrow irrigation. When combined with precision planting, sprinkler irrigation resulted in earlier maturity of lettuce as well as highest yields obtained from a single harvest. Further studies will be needed to re-evaluate cultural practices involved in changing from furrow to sprinkler irrigation.
Effects of irrigation treatments on barley yields
by H. Yamada , B. B. Fischer , C. R. Pomeroy
To obtain maximum yields of barley in the San Joaquin Valley, a normal (12″ to 14″) pre-irrigation and at least one supplemental crop irrigation are required, according to these studies. When a heavy pre-irrigation is applied, the soil may be wetted below the potential rooting depth of the barley, in which case the moisture would not be available to the plants.
Effect of winter chilling on Bartlett pear and Jonathan apple trees
by D. S. Brown , W. H. Griggs , B. T. Iwakiri
Observations of the test trees in this study indicate that (presumably because of in-continuity of chilling) a varying portion of apple and pear buds may fail to open, even after a winter such as 1964–65 which provided 1,560 hours of chilling temperatures. Good chilling during both December and January is especially critical. Since winter-chilling is insufficient, or poorly distributed in the important pear-producing districts of the state more often than in the apple districts, the results emphasize the importance of heading back vigorous upright branches on young pear trees to insure near-to-normal foliation and branching. Except after the mildest winters, or with varieties having a high chilling requirement like Rome Beauty, such a pruning practice is seldom beneficial on apple trees, however.
Control of strawberry powdery mildew
by A. O. Paulus , Victor Voth , Fujio Shibuya , H. J. Bowen , A. H. Holland , T. M. Little
Morestan gave outstanding control of strawberry powdery mildew in three yea.rs of trials at South Coast Field Station, Santa Ana. Morocide and sulfur were erratic in control. Neither Morestan nor Morocide can be recommended by University of California at this time for the control of strawberry powdery mildew. Morocide is not yet registered for use on strawberries, and Murestan is registered for use only on nonbearing plants (cannot be used after first blooms appear).