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California Agriculture, Vol. 42, No.4

Download Cover PDF
Cover:  Unless disrupted by sprays for other walnut pests, a parasitic wasp usually keeps walnut aphids under control in orchards. Aphid mummy, seen with walnut aphids on a leaf in the cover photo, shows evidence of parasitization by the wasp, Trioxys pallidus, which lays an egg inside each aphid host. The developing parasite kills the aphid, transforms it into a mummy, and eventually emerges as an adult. Researchers have developed a resistant strain of the wasp, which they hope will be able to survive Guthion sprays applied to control coddling moth and navel orangeworm in walnut orchards. Cover photo by Jack Kelly Clark
July-August 1988
Volume 42, Number 4
PDF of Issue | View Abstracts

Peer-reviewed research and review articles

Guthion-resistant strain of walnut aphid parasite
by Marjorie A. Hoy, Frances E. Cave
| Full text HTML  | PDF  
Unless disrupted by sprays for other walnut pests, a parasitic wasp usually keeps walnut aphids under control in orchards. Aphid mummy, seen with walnut aphids on a leaf in the cover photo, shows evidence of parasitization by the wasp. Trioxys pallidus, which lays an egg inside each aphid host. The developing parasite kills the aphid, transforms it into a mummy, and eventually emerges as an adult. Researchers have developed a resistant strain of the wasp, which they hope will be able to survive Guthion sprays applied to control coddling moth and navel orangeworm in walnut orchards. Cover photo by Jack Kelly Clark
A laboratory-selected strain of the parasitic wasp Trioxys pallidus is ready for field trials
Acid fog injures California crops
by Robert C. Musselman, Patrick M. McCool, Jerry L. Sterrett
| Full text HTML  | PDF  
Acid fog can reduce marketability and sometimes yield of some crops, but most plants are quite tolerant
The effect of acid rain on agricultural crops has been studied extensively in the past decade by plant scientists in the United States. Research has shown that agricultural crops can be injured as acidity in rain approaches pH 3. Since this level of acidity is rarely reached in normal rainfall in California, acid rain had been thought to be of little or no consequence to agriculture in this state.
Persimmons for California
by Kay Ryugo, Charles A. Schroeder, Akira Sugiura, Keizo Yonemori
| Full text HTML  | PDF  
Persimmon cultivars of varied types have been grown in California since very early importations from Asia.
Although the name ‘persimmon’ is American, of Algonquian origin, the major cultivars grown commercially in California belong to a species first brought to the United States from Japan in the 1800s. Most of these cultivars have distinct differences in fruit size, shape, and color.
Effect of permethrin on house fly resistance
by Jeffery A. Meyer, George P. Georghiou
| Full text HTML  | PDF  
Lab tests confirm house fly resistance to permethrin on southern California dairies that regularly apply sprays.
Resistance has developed on several southern California dairies that have had to rely on regular permethrin treatments
California wheat as a feed ingredient for turkeys
by Kirk C. Klasing, Susan A. Klasing, David M. Barnes
| Full text HTML  | PDF  
Wheat can be substituted for corn in least cost turkey rations, if accurate nutritional information is used.
Although wheat is normally considered a grain primarily for human food, it has been used successfully in poultry diets for many years. The amount of wheat included in a least-cost ration formulation depends largely on the price of wheat relative to that of corn or other energy-providing feedstuffs and, to a lesser extent, the price of fat and protein sources. In recent years, considerable amounts of wheat have been included in least-cost formulations for poultry because of a variety of agronomic, economic, and political circumstances.
Controlling powdery mildew and rust in roses
by Albert O. Paulus, Jerry Nelson
| Full text HTML  | PDF  
Registered fungicides gave intermediate or good control of the diseases. Some new materials look promising
Powdery mildew is undoubtedly the most widespread disease of roses. The causal fungus, Sphaerotheca pannosa var. rosae, appears as a white or gray powdery or mealy coating on the leaves, tender stems, and flower buds. It distorts and discolors those areas, causes defoliation, and reduces plant vigor.
Computer use in Tulare County agriculture
by Daniel S. Putler, David Zilberman
| Full text HTML  | PDF  
About 25 percent of farmers surveyed used computers.; they tended to be well-educated, large-farm operators.
About a fourth of the farmers surveyed used computers, more often for general ledger and similar applications than as crop management and production-decision aids
Chemical growth regulator for peaches
by Frank T. Yoshikawa, George C. Martin, James H. LaRue
| Full text HTML  | PDF  
Paclobutrazole reduced vegetative growth and increased yield in early-maturing, close-planted peaches.
Excessive vegetative growth in peach orchards shades the lower portions of trees and decreases fruit bud development, makes expensive summer pruning necessary, and causes crowding between trees in close plantings. The problem is greatest in early-maturing peach cultivars. In trees harvested in May to July, top growth continues until the end of summer; the competitive effect of fruit, which decreases the summer vegetative growth of later maturing cultivars, is reduced after harvest.
Benefits and costs of improving pumping efficiency
by Blaine R. Hanson
| Full text HTML  | PDF  
Energy savings from pump repair or replacement depend on management of the irrigation system.
Pump repair or replacement can substantially improve performance, but energy savings will depend on management of the irrigation system
Oak stand growth on California's hardwood rangelands
by Richard B. Standiford, Richard E. Howitt
| Full text HTML  | PDF  
Methods of assessing stand productivity have been devised as a first step in forming management strategies.
Estimating a stand's productivity is a preliminary step in devising management strategies for multiple uses of a site
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California Agriculture > Volume 42 > Number 4 > 

< Previous issue |   Next issue >

>< Previous issue |   Next issue >

California Agriculture, Vol. 42, No.4

Download Cover PDF
Cover:  Unless disrupted by sprays for other walnut pests, a parasitic wasp usually keeps walnut aphids under control in orchards. Aphid mummy, seen with walnut aphids on a leaf in the cover photo, shows evidence of parasitization by the wasp, Trioxys pallidus, which lays an egg inside each aphid host. The developing parasite kills the aphid, transforms it into a mummy, and eventually emerges as an adult. Researchers have developed a resistant strain of the wasp, which they hope will be able to survive Guthion sprays applied to control coddling moth and navel orangeworm in walnut orchards. Cover photo by Jack Kelly Clark
July-August 1988
Volume 42, Number 4
PDF of Issue | View Abstracts

Peer-reviewed research and review articles

Guthion-resistant strain of walnut aphid parasite
by Marjorie A. Hoy, Frances E. Cave
| Full text HTML  | PDF  
Unless disrupted by sprays for other walnut pests, a parasitic wasp usually keeps walnut aphids under control in orchards. Aphid mummy, seen with walnut aphids on a leaf in the cover photo, shows evidence of parasitization by the wasp. Trioxys pallidus, which lays an egg inside each aphid host. The developing parasite kills the aphid, transforms it into a mummy, and eventually emerges as an adult. Researchers have developed a resistant strain of the wasp, which they hope will be able to survive Guthion sprays applied to control coddling moth and navel orangeworm in walnut orchards. Cover photo by Jack Kelly Clark
A laboratory-selected strain of the parasitic wasp Trioxys pallidus is ready for field trials
Acid fog injures California crops
by Robert C. Musselman, Patrick M. McCool, Jerry L. Sterrett
| Full text HTML  | PDF  
Acid fog can reduce marketability and sometimes yield of some crops, but most plants are quite tolerant
The effect of acid rain on agricultural crops has been studied extensively in the past decade by plant scientists in the United States. Research has shown that agricultural crops can be injured as acidity in rain approaches pH 3. Since this level of acidity is rarely reached in normal rainfall in California, acid rain had been thought to be of little or no consequence to agriculture in this state.
Persimmons for California
by Kay Ryugo, Charles A. Schroeder, Akira Sugiura, Keizo Yonemori
| Full text HTML  | PDF  
Persimmon cultivars of varied types have been grown in California since very early importations from Asia.
Although the name ‘persimmon’ is American, of Algonquian origin, the major cultivars grown commercially in California belong to a species first brought to the United States from Japan in the 1800s. Most of these cultivars have distinct differences in fruit size, shape, and color.
Effect of permethrin on house fly resistance
by Jeffery A. Meyer, George P. Georghiou
| Full text HTML  | PDF  
Lab tests confirm house fly resistance to permethrin on southern California dairies that regularly apply sprays.
Resistance has developed on several southern California dairies that have had to rely on regular permethrin treatments
California wheat as a feed ingredient for turkeys
by Kirk C. Klasing, Susan A. Klasing, David M. Barnes
| Full text HTML  | PDF  
Wheat can be substituted for corn in least cost turkey rations, if accurate nutritional information is used.
Although wheat is normally considered a grain primarily for human food, it has been used successfully in poultry diets for many years. The amount of wheat included in a least-cost ration formulation depends largely on the price of wheat relative to that of corn or other energy-providing feedstuffs and, to a lesser extent, the price of fat and protein sources. In recent years, considerable amounts of wheat have been included in least-cost formulations for poultry because of a variety of agronomic, economic, and political circumstances.
Controlling powdery mildew and rust in roses
by Albert O. Paulus, Jerry Nelson
| Full text HTML  | PDF  
Registered fungicides gave intermediate or good control of the diseases. Some new materials look promising
Powdery mildew is undoubtedly the most widespread disease of roses. The causal fungus, Sphaerotheca pannosa var. rosae, appears as a white or gray powdery or mealy coating on the leaves, tender stems, and flower buds. It distorts and discolors those areas, causes defoliation, and reduces plant vigor.
Computer use in Tulare County agriculture
by Daniel S. Putler, David Zilberman
| Full text HTML  | PDF  
About 25 percent of farmers surveyed used computers.; they tended to be well-educated, large-farm operators.
About a fourth of the farmers surveyed used computers, more often for general ledger and similar applications than as crop management and production-decision aids
Chemical growth regulator for peaches
by Frank T. Yoshikawa, George C. Martin, James H. LaRue
| Full text HTML  | PDF  
Paclobutrazole reduced vegetative growth and increased yield in early-maturing, close-planted peaches.
Excessive vegetative growth in peach orchards shades the lower portions of trees and decreases fruit bud development, makes expensive summer pruning necessary, and causes crowding between trees in close plantings. The problem is greatest in early-maturing peach cultivars. In trees harvested in May to July, top growth continues until the end of summer; the competitive effect of fruit, which decreases the summer vegetative growth of later maturing cultivars, is reduced after harvest.
Benefits and costs of improving pumping efficiency
by Blaine R. Hanson
| Full text HTML  | PDF  
Energy savings from pump repair or replacement depend on management of the irrigation system.
Pump repair or replacement can substantially improve performance, but energy savings will depend on management of the irrigation system
Oak stand growth on California's hardwood rangelands
by Richard B. Standiford, Richard E. Howitt
| Full text HTML  | PDF  
Methods of assessing stand productivity have been devised as a first step in forming management strategies.
Estimating a stand's productivity is a preliminary step in devising management strategies for multiple uses of a site

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