April 1976

Cover: An aerial photo taken in September (top) shows apparent uniform growth and color except for a few thin spots in the vineyard. A color infrared photo taken six months later (below) shows drying and defoliation of vines on shallow soil areas, but excessive foliag growth on deep soil areas.

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California Agriculture, April 1976

Volume 30, Number 4

research articles

Low-cost aerial photography for agricultural management
by William E. Wildman , Rudy A. Neja , Jack K. Clark
pp4-7, doi#10.3733/ca.v030n04p4
Abstract
We greatly appreciate support of the aerial photo program by Monterey County Grape Growers Assoc., Salinas Valley Vineyards, Wente Brothers, Mirassou Vineyards, Paul Masson Vineyards, Occidental Chemical Co., Dow Chemical Co., J. G. Boswell Co., and Feather River Mt. Lassen Christmas Tree Assoc. Thanks are also due Dr. Philip Langley of Earth Satellite Corp. for preparing the electronic image enhancements.
Expanded Abstract | PDF

Computer model aids in weevil control
by A. P. Gutierrez , U. Regev , C. G. Summers
pp8-9, doi#10.3733/ca.v030n04p8
Abstract
Not available – first paragraph follows: During the late 1950's, the Egyptian alfalfa weevil invaded alfalfa in the desert regions of the southwestern United States. In 1974, it caused in excess of 18 million dollars in damage (1974 California Department of Food and Agriculture Report). This is not surprising as, under certain circumstances, this pest can completely defoliate a crop. In addition, the routine pesticide applications which have been directed against this pest appear to have induced secondary pest outbreaks of other formerly innocuous pests (e.g., aphids, mites and various Lepidoptera), which also, require further pesticide applications to control them. The problems of increasing pesticide applications and the associated costs are so severe that they jeopardize the economical cultivation of alfalfa in the central valley of California.
Expanded Abstract | PDF

Club root control in brussels sprouts using lime for pH adjustment
by N. Welch , A. S. Greathead , J. Inman , J. Quick
pp10-11, doi#10.3733/ca.v030n04p10
Abstract
Not available – first paragraph follows: Club root, incited by Plasmodiophora brassicae (Woronin), is one of the most serious diseases of plants of the crucifer family and is a threat to crop production wherever it occurs. In heavily infested soil, it is capable of destroying a crop before it reaches market maturity.
Expanded Abstract | PDF

‘Durado’—A new fresh market plum
by Claron O. Hesse
pp12-13, doi#10.3733/ca.v030n04p12
Abstract
Not available – first paragraph follows: Durado, an early maturing Japanese plum, resulted from a cross made in 1966 (see figure). It was selected in 1969, propagated at the Kearney Horticultural Field Station in the same year, and placed in several authorized grower-cooperative trial plantings in Fresno, Tulare, Kings, and Kern counties in 1972 and 1973. Several of these test plantings bore fruit in 1975. It was tested as Selection 9,27-58.
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Blue alfalfa aphid: A new pest in the imperial valley
by R. K. Sharma , V. M. Stern , R. W. Hagemann
pp14-15, doi#10.3733/ca.v030n04p14
Abstract
Not available – first paragraph follows: Specimens of this new aphid were unknowingly collected by one of the authors from alfalfa near Bakersfield, California in 1974. The samples were taken to detect lygus bug parasites and the aphids in the samples were not counted. Fortunately, the samples were preserved for other observations. When the new aphid reached outbreak numbers in 1975, the Bakersfield samples were reexamined and specimens of the new aphid were identified by R. C. Dickson, U.C. Riverside.
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Monitoring pear scab in mendocino county
by B. E. Bearden , W.J. Moller , W. O. Reil
pp16-19, doi#10.3733/ca.v030n04p16
Abstract
Not available – first paragraph follows: Pear scab (Venturia pirina) has come more prevalent in recent years in the north coastal regions, especially in Mendocino County. A closely related fungus causes apple scab (Venturiu inaequalis) but does not affect pears, although the life cycles, infection requirements, and even control measures for apple and pear scab are remarkably similar. While apple scab research is ample and worldwide in scope, the applicability of some of this research to pear scab California has not been established.
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Control of hillside seepage in avocado and citrus orchards
by R. M. Burns , B. W. Lee , F. K. Aljibury , J. L. Meyer
pp20-21, doi#10.3733/ca.v030n04p20
Abstract
Not available – first paragraph follows: Many of the citrus and avocado orchards near the foothills of Ventura and Orange counties are damaged by root disease and excessive wetness from hillside seepage. The damage is most severe during wet years or when the adjacent hills are excessively irrigated (see fig. 1). Dense subsoil and steep topographical conditions cause excess water from rain or irrigation to seep underground downslope creating a drainage problem (see fig. 2).
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Alfalfa seed underground drip irrigation
by R.W. Hagemann , L.S. Willardson , A.W. Marsh , C.F. Ehlig
pp22, doi#10.3733/ca.v030n04p22
Abstract
Not available – first paragraph follows: Five underground drip irrigation systems with varied, emitter spacings were evaluated for alfalfa seed production in the Imperial Valley. Previously, higher seed yields had been produced with a 50-centibar soil water tension at 9 inches below surface drip lines than with soil water tensions of 10, 100, and 200 centibars (see California Apiculture, November 1975). Since surface drip lines are subject to sunlight and mechanical damage, we began an evaluation of five underground drip irrigation systems for alfalfa seed production in November 1973 at the Imperial Valley Conservation Research Center near Brawley. The five systems with indicated emitter spacings were: (1) Chapin, continuous (a biwall system with orifices spaced 32 inches on the inside tube and water seeping through a nylon-sewn seam on the outside tube); (2) Chapin, 8.”; (3) Watersaver, 24”; (4) Nelco, 24”; and (5) Anjac, 36”. The main objective was to determine the effect of emitter spacings on alfalfa seed yield rather than to compare commercially available drip lines.
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editorial, news, letters & science briefs

EDITORIAL: Our most valuable resource
by J. B. Kendrick
pp2, doi#10.3733/ca.v030n04p2
PDF

Supplemental salt may be unnecessary
Editors
pp3, doi#10.3733/ca.v030n04p3a
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Timber shortage
Editors
pp3, doi#10.3733/ca.v030n04p3b
PDF

Lowest farm population
Editors
pp3, doi#10.3733/ca.v030n04p3c
PDF

Meadowfoam as a new oil crop
Editors
pp3, doi#10.3733/ca.v030n04p3d
PDF