March 1969

Cover: A severe bee kill resulted from insecticide applications to a safflower field two miles away during experiments with supplemental feeding of honey bee colonies in a Fresno County alfalfa seed field.

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California Agriculture, March 1969

Volume 23, Number 3

research articles

Tillage increases plant diseases
by C. E. Yarwood
pp4-6, doi#10.3733/ca.v023n03p4
Abstract
Tillage practices have contributed greatly to increasing crop production. However, speculation and controversy have surrounded such practices as to the question of whether tillage increases or decrease: the incidence of disease in the growing crop. This study substantiates recent investigations indicating that tillage does, in fact, generally increase the incidence of plant diseases.
Expanded Abstract | PDF

Surfactant longevity and wetting characteristics
by J. F. Osborn , J. Letey , N. Valoras
pp6-8, doi#10.3733/ca.v023n03p6
Abstract
Abstract Not Available – First paragraph follows: OBSERVATIONS of water repellency in soils made over the past 10 years throughout the world have indicated that this particular problem is more important than had previously been thought. There have been reports that water repellency in golf greens and lawns is responsible for drought conditions even though the grass has had sufficient watering. This condition of water repellency has often been associated with thatch buildup. Nurserymen have noted that many of the soil mixes they use for potting plants are hard to wet.
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Effects of irrigation, crop density on almond trunk growth
by K. Uriu , P. E. Martin , R. M. Hagan
pp8-11, doi#10.3733/ca.v023n03p8
Abstract
Trunk growth studies of almonds at Davis have given new information about the need for spring irrigation. A lever-type dendrometer developed at the University of Idaho was used to follow trunk growth patterns for four consecutive years under widely varying conditions of soil, water, and crop density. The study has shown that the need for early irrigation increases when there is a heavy crop. In the spring, trunk growth rates were increased by irrigation even when as much as 40 per cent available water still remained in the top 4 ft of soil. After mid-season, trunk growth rates were not increased by irrigation unless the soil water content had dropped to the plant wilting percentage before irrigation. These studies also showed that trunk growth rates were reduced as the crop density increased.
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Honey bee pollination of alfalfa seed improved by supplemental feeding
by Bob Sheesley , Bernard Poduska
pp11-13, doi#10.3733/ca.v023n03p11
Abstract
Results of these Fresno County experiments indicate possible advantages to both alfalfa seed growers and beekeepers from the use of supplemental feeding, and requeening of bee colonies used in alfalfa pollination.
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Mechanical harvesting for green asparagus
by R. A. Kepner , R. E. Cowden , G. I. Weigt
pp14-17, doi#10.3733/ca.v023n03p14
Abstract
Results of 1968 Tests Indicate that Substantial Reductions in Yield of Green Asparagus can be Expected with Selective Mechanical Harvesting, as well as with Nonselective Harvesting. Under Present Conditions a Grower's Net Profit Would be Reduced if he Changed from Hand Cutting to Either System of Mechanical Harvesting. A More Detailed Report on these Tests is Available, Upon Request, from the Department of Agricultural Engineering, University of California, Davis.
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Wood processing residues —disposal and use in Shasta County
by William A. Dost
pp17-18, doi#10.3733/ca.v023n03p17
Abstract
Abstract Not Available – First paragraph follows: WOOD PRODUCTS MANUFACTURE is a vital segment of the economy of Shasta County; however, as with most industry, it is not an unmixed blessing. Wood products manufacture is essentially a reduction process and residues generated at each stage have become increasingly acute in recent years. Operators are faced with the necessity of increasing the percentage of raw material converted to marketable products in order to maintain a competitive position. On the other hand, they are faced with increasing pressure from the community to reduce or eliminate the smoke and ash problems caused by common residue disposal methods.
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Plastic shelters for crop growth experiments in the field
by V. H. Schweers , R. M. Davis
pp19, doi#10.3733/ca.v023n03p19
Abstract
Abstract Not Available – First paragraph follows: SHELTERS ARE often necessary in experimental work with growing crops to protect research results from the influence of insects or insect-transmitted viruses or other diseases—without greatly altering the other important factors of environment such as light, soil and temperature. This article resulted from a study of the low sugar problem threatening cantaloupe production in several areas of the San Joaquin Valley. It describes a simple inexpensive framework covering a ground area 20 by 30 ft, and reports measurements of light, temperature and humidity within several such structures covered with various combinations of polyethylene and cheesecloth.
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editorial, news, letters & science briefs

EDITORIAL: Frustration— agriculture and research
by J. H. Meyer
pp2, doi#10.3733/ca.v023n03p2
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General Information

Environmental toxicology University of California, Davis
Editors
pp3, doi#10.3733/ca.v023n03p3
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