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California Agriculture, August 1977

Volume 31, Number 8

research articles

CUF 101, a new variety of alfalfa is resistant to the blue alfalfa aphid
by William F. Lehman, Mervin W. Nielson, Vern L. Marble, Ernest H. Stanford
pp4-5, doi#10.3733/ca.v031n08p4
Abstract
A new, resistant variety of alfalfa was quickly developed once the blue alfalfa aphid was recognized as a pest
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Program Review: Research seeks new ways to combat mosquitoes
by Edmond C. Loomis, Russell E. Fontaine, Robert M. Boardman
pp6-7, doi#10.3733/ca.v031n08p6
Abstract
Abstract Not Available – First paragraph follows: Working with 63 mosquito control agencies throughout the state, University of California researchers have completed three major mosquito control projects:
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Russet crack disease of sweet potatoes
by Robert N. Campbell, Robert W. Scheuerman, Dennis H. Hall
pp8-10, doi#10.3733/ca.v031n08p8
Abstract
Abstract Not Available – First paragraph follows: Russet crack disease of sweet potatoes (Ipomoea batatas) was first reported in New Jersey in 1961 and it was suggested a virus might be the cause. Soon after, the disease was in California; probably it had been imported with propagative roots from the east coast. The present paper reports studies done at the University of California at Davis and in Merced County, California, to clarify the cause of russet crack and its method of transmission.
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Wheat and barley response to nitrogen
by Y. Paul Puri, Kenneth G. Baghott, John D. Prato
pp10-11, doi#10.3733/ca.v031n08p10
Abstract
Abstract Not Available – First paragraph follows: Wheat and barley are important crops to the Tulelake Basin and other intermountain valleys of northern California. Both bread wheats and durum wheats are grown. Barley is used for malting and as a feed grain. The yields of barley and wheat vary widely from field to field and from year to year, ranging from 2000 to 7000 pounds per acre. These fluctuations are attributed to climatic and soil factors, and to the cultural practices followed.
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Research Review: Antibiotic injections control pear decline disease
by James A. Beutel, William J. Moller, Forrest D. Cress
pp12-13, doi#10.3733/ca.v031n08p12
Abstract
Abstract Not Available – First paragraph follows: After more than a decade of devastating orchard losses to pear decline, the disease is now under effective control.
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Sunlight and temperature effects on corn growth and yield
by William G. Duncan, Donald L. Shaver, William A. Williams
pp13-14, doi#10.3733/ca.v031n08p13
Abstract
Abstract Not Available – First paragraph follows: Grain yields of corn in the United States differ considerably between one area and another even when soil fertility and moisture supply are considered near-optimal. Reason for such variation are difficult to evaluate because direct comparisons are confused by difference in sunlight amount, temprature, photoperiod, and variety.
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Four new shipping freestone peaches for California
by Claron O. Hesse
pp15, doi#10.3733/ca.v031n08p15
Abstract
Abstract Not Available – First paragraph follows: Firered, Redcal, Kearney, and Calred are four new freestone shipping peaches introduced by the University of California in 1977. All are highly colored clones, ripening in the above named sequence from about August 1 to August 25, as shown in the table. Their pedigrees are given in figure 1.
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Flue dusts as zinc fertilizers
by A. Lloyd Brown, Richard G. Burau, David R. Giger
pp16-17, doi#10.3733/ca.v031n08p16
Abstract
Abstract Not Available – First paragraph follows: As pollution control becomes more and more important, many industrial plants must collect particulate matter from their stacks which would otherwise be distributed over the nearby landscape. Some of these materials, with or without further treatment, are being sold or potentially could be sold as micronutrient fertilizers, especially zinc fertilizer. The efficacy of these materials in comparison to zinc sulfate (ZnSO4), which is the most common zinc (Zn) fertilizer at the present time, was investigated.
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Ethephon has mixed effects on table grapes
by Fred Jensen, Harry Andris
pp18, doi#10.3733/ca.v031n08p18
Abstract
Abstract Not Available – First paragraph follows: The growth regulator ethephon (Ethrel) has been shown to improve coloring of the table grape varieties, Red Malaga, Queen, Tokay, and Emperor if applied after some of the berries have begun to show color. Preliminary trials with Cardinals showed slight color benefits, of dubious commercial significance. Trials with Ribier have never shown benefit. More detailed trials were established at the Kearney Horticultural Field Station near Parlier in Fresno County during the 1976 season.
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Corn tops sorghum in comparison trials
by Thomas E. Kearney, Karl H. Ingebretsen, John D. Prato
pp19, doi#10.3733/ca.v031n08p19
Abstract
Abstract Not Available – First paragraph follows: Grain sorghum has been grown as the second crop in double crop systems in California agriculture for years. Its use has been marginally profitable, especially in occasional years with early, wet falls. Growers interested in greater profits began investigating the possibility of substituting early maturing corn varieties for grain production in place of sorghum. When grown as a full season crop, corn usually shows a yield advantage over grain sorghum. These comparisons by growers indicated that corn did have a potential yield advantage over sorghum as a double crop and also showed the ability to overwinter when early autumn rains made fall harvests impossible.
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Editorial, News, Letters and Science briefs

EDITORIAL: A new era—but a continuing challenge
by J. B. Kendrick
pp2, doi#10.3733/ca.v031n08p2
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Effect of insect numbers on aphid transmission of potato leafroll virus

by Onkar Singh Bindra, Edward S. Sylvester
pp279-325, doi#10.3733/hilg.v31n08p279
Abstract
Abstract does not appear. First page follows.Introduction It is generally agreed that inoculations by individuals of a group of vectors are separate and independent events, and that virus transmission efficiency by groups of insects will follow that predicted by probabilities generated by expansion of the binomial theorem (Watson, 1936; Storey, 1938; Watson and Roberts, 1939; Posnette and Robertson, 1950; Storey and Ryland, 1955; Sylvester, 1955, 1956). 5 However, Kirkpatrick and Ross (1952) reported that in the transmission of potato leafroll virus by Myzus persicae (Sulz.) to Physalis angulata the rate of successful inoculation by groups was lower than expected on the basis of this hypothesis, and that the efficiency of individuals in a group decreased as the size of the group was increased. They considered that this could be due to one or more of the following: (1) the presence of immune or highly resistant plants in the test plant population which would not become systemically infected in spite of the presence of relatively large numbers of vectors per plant and relatively long inoculation access periods; (2) interference of aphids with one another which could prevent feeding by any one of them for a period long enough for transmission of this virus; and (3) aphids feeding for relatively long periods tended to cause the test plants to become more resistant to systemic infection by this virus. A fourth hypothesis (4) might be added, viz., that such observations are due to chance variation. In the following work, tests were designed in an attempt to specifically test each of these four hypotheses. Williams and Ross (1957) stated that their data suggested that the susceptibility of Physalis angulata was decreased by aphid feeding, but that this effect was not great enough to explain entirely the relative inefficiency of individuals in a colony. However, in both this and the original work (Kirkpatrick
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Effect of insect numbers on aphid transmission of potato leafroll virus

by Onkar Singh Bindra, Edward S. Sylvester
pp279-325, doi#10.3733/hilg.v31n08p279
Abstract
Abstract does not appear. First page follows.Introduction It is generally agreed that inoculations by individuals of a group of vectors are separate and independent events, and that virus transmission efficiency by groups of insects will follow that predicted by probabilities generated by expansion of the binomial theorem (Watson, 1936; Storey, 1938; Watson and Roberts, 1939; Posnette and Robertson, 1950; Storey and Ryland, 1955; Sylvester, 1955, 1956). 5 However, Kirkpatrick and Ross (1952) reported that in the transmission of potato leafroll virus by Myzus persicae (Sulz.) to Physalis angulata the rate of successful inoculation by groups was lower than expected on the basis of this hypothesis, and that the efficiency of individuals in a group decreased as the size of the group was increased. They considered that this could be due to one or more of the following: (1) the presence of immune or highly resistant plants in the test plant population which would not become systemically infected in spite of the presence of relatively large numbers of vectors per plant and relatively long inoculation access periods; (2) interference of aphids with one another which could prevent feeding by any one of them for a period long enough for transmission of this virus; and (3) aphids feeding for relatively long periods tended to cause the test plants to become more resistant to systemic infection by this virus. A fourth hypothesis (4) might be added, viz., that such observations are due to chance variation. In the following work, tests were designed in an attempt to specifically test each of these four hypotheses. Williams and Ross (1957) stated that their data suggested that the susceptibility of Physalis angulata was decreased by aphid feeding, but that this effect was not great enough to explain entirely the relative inefficiency of individuals in a colony. However, in both this and the original work (Kirkpatrick
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