California Agriculture, July 1967

Volume 21, Number 7
Russian thistle seed 61 minutes after being exposed to water. Spiral action of the unwinding embryo forces root into loose soil.

research articles

Germination of Russian thistle seeds
by W. A. Rhoads , E. F. Frolich , Arthur Wallace
pp2, doi#10.3733/ca.v021n07p2
Abstract
Russian thistle seeds are remarkably adapted for survival of the species under semiarid conditions, but they do not survive on undisturbed soils.
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Seed contamination in transmission of halo blight in beans
by R. G. Grogan , K. A. Kimble
pp3-4, doi#10.3733/ca.v021n07p3
Abstract
This paper presents evidence that seed transmission of halo blight can result from infestation as well as infection, and that infestation probably is more important, especially under furrow irrigation in low rainfall areas where secondary spread during the growing season is rare or nil.
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Inducing abscission of olive fruits by spraying with ascorbic acid and iodoacetic acid
by Hudson T. Hartmann , Mostafa Fadl , John Whisler
pp5-7, doi#10.3733/ca.v021n07p5
Abstract
Abstract Not Available – First paragraph follows: Mechanical harvesting of olive fruits with commercially available tree shakers has not been completely satisfactory because the energy output of such shakers is usually insufficient to readily remove a high percentage of fruit. Specially constructed shakers with a high-energy output have been shown to be able to detach the fruit, however.
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Chemical identification of pear species used as rootstocks
by P. B. Catlin , E. A. Olsson
pp8-9, doi#10.3733/ca.v021n07p8
Abstract
Paper chromatograms of leaf extracts of five pear species and one interspecific F1 hybrid. All detectable spots—mostly polyphenolic compounds—are marked. Components used for identification are indicated by solid lines and are numbered. Spot size and, for some, color intensity are indicative of amounts present.
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Diagnoses of pear decline and rootstock identification in young pear orchards
by P. B. Catlin , A. A. Millecan
pp10-11, doi#10.3733/ca.v021n07p10
Abstract
Abstract Not Available – First paragraph follows: Pear decline has occurred predominantly with rootstocks of two oriental species, Pyrus serotina and P. ussuriensis, although there have been reports of tree losses with P. communis rootstocks. Most of the latter have been of the “old” French type imported from Europe prior to 1918. While decline has occasionally been suspected with additional types of P. communis rootstocks (domestic French), generally this species has been tolerant to decline. Although certain seedlings of P. communis have frequently been referred to as resistant or immune, some uncertainty now prevails regarding such resistance. Diagnosis of decline often has been made without microscopic examination of bud unions, and even when bud unions have been examined for phloem abnormalities, the identity of the rootstock may be open to question.
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Light traps as detection devices for moths of cabbage looper and bollworm
by L. A. Falcon , R. van den Bosch , L. K. Etzel , C. A. Ferris , L. K. Stromberg
pp12-14, doi#10.3733/ca.v021n07p12
Abstract
In a 1966 test, blacklight insect traps effectively trapped moths of cabbage looper and bollworm in a Fresno County cotton field. Increased collections of moths in the traps were followed by a rise in egg and larval populations in the field. Light trap information used together with established field-checking procedures can aid in determining the need for control measures of these pests. More detailed information is available in Leaflet 197, “Light Traps and Moth Identification,” available at local Farm Advisor offices.
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Dual-use return-water irrigation system
by F. K. Aljibury , J. W. Brown , C. E. Houston
pp14-15, doi#10.3733/ca.v021n07p14
Abstract
This study indicates that where tail water is a necessity to provide an appreciable increase in production of a relatively high-value crop, a large investment in the irrigation return-water system can still be economically feasible.
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General Information

Research previews
Editors
pp11, doi#10.3733/ca.v021n07p11
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