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California Agriculture, Vol. 45, No.6

Loma Vista Farm: learn-by-doing lab for kids
Cover:  On a visit to Loma Vista Farm, Vallejo School district students conduct tests of soil acidity – part of a lesson on sustainable agriculture. Cover photo by Jack Kelly Clark
November-December 1991
Volume 45, Number 6

Peer-reviewed research and review articles

Toxics, food safety, water quality “most important”: How California educators and CE directors view “agricultural literacy” programs
by Marc T. Braverman, Ellen L. Rilla
| Full text HTML  | PDF  
While California'seducational administrators view agricultural literacy as important, new programs must compete for limited classroom resources.
Agricultural literacy programs —now underway in a few California schools — are designed to provide students with a fundamental understanding of how our agricultural system works, including its relationship to natural resources and the environment. In statewide surveys, public school administrators and CE county directors agreed such programs should be incorporated into science or social studies classes during late elementary and middle grades. District administrators identified the most important topics to be toxics in the environment, toxics in the food supply, and water quality and policy. Groups surveyed expressed differing opinions, however, about the plant Of teaching the topic in schools.
Sidebar: Snapshots of current agricultural literacy programs
by Ellen L. Rilla, Daniel J. Desmond, Marc T. Braverman, Richard Ponzio, Faye Lee, Elizabeth Sandlin, Carol Kaney
| Full text HTML  | PDF  
Summary Not Available – First paragraph follows: Site visits to selected schools provided snapshots of agricultural literacy programs across the state. Schools were chosen to represent a wide variety of situations.
Abstract Not Available – First paragraph follows: Site visits to selected schools provided snapshots of agricultural literacy programs across the state. Schools were chosen to represent a wide variety of situations.
New strain of sweetpotato whitefly invades California vegetables
by Thomas M. Perring, Arthur Cooper, Dave J. Kazmer, Clyde Shields, Jon Shields
| Full text HTML  | PDF  
Since 1990, a new strain of sweetpotato whitefly has inflicted heavy damage on vegetable crops statewide.
In 1990, a new strain of sweetpotato whitefly invaded Southern California agricultural regions, inflicting heavy damage on cruciferous crops, Problems related to this new strain have impacted vegetable growers throughout California and other growing regions. In the Imperial Valley, 95% of the 1991 fall melons were disced and total losses to summer and fall crops have been estimated at over $120 million.
Farmworker injury and illness: statistical guides to prevention
by Stephen R. Sutter
| Full text HTML  | PDF  
Farm accident and illness statistics can be used to develop mandated Injury and Illness Prevention Programs.
Requirements mandated by the historic statute Senate Bill 198 include identifying occupational safety and health hazards and training current supervisory and other employees in coping with general agricultural hazards. This review of accident and illness statistics for agriculture may be useful in developing a written Injury and Illness Prevention Program.
Strategies needed for oak protection: Despite landowner favor, oak groves likely to diminish in size and number
by R. H. Schmidt
| Full text HTML  | PDF  
Although landowners report numerous advantages to owning oak groves, strategies are needed to save or replant them.
A survey of landowners in unincorporated parts of Yolo County indicates that they perceive many advantages and few drawbacks to oak-grove ownership. Valley oak acreage is used for farming, wildlife habitat, livestock grazing, houses and outbuildings, and firewood production. However, without new strategies to protect and replace them, existing groves will most likely decrease in size and distribution as properties turn over and new owners and management concerns take over.
Stress-adapted landscapes save water, escape injury in drought
by Roy M. Sachs
| Full text HTML  | PDF  
If adapted to reduced irrigation over a 2-year period, established shrubs and ground covers show no drought-related injury.
Results of investigations at UC experiment stations reveal that irrigation equal to 14% or less of reference evapotranspiration (ETO) can be applied to established shrubs and ground covers with no apparent drought-related injury. Adaptation to stress by reduced irrigation during the 2 years preceding full reduction of irrigation eliminated most injury symptoms (such as wilting and leaf necrosis). Application of these findings to established landscapes should significantly reduce water use and the cost of removing excess vegetation.
Subsurface drip irrigation of tomatoes: Drip system design, management promote seed emergence
by Larry Schwankl, Stephen R. Grattan, Gene M. Miyao
| Full text HTML  | PDF  
Investigators showed that design and management of a drip irrigationsystem could ensure adequate soil moisture for tomatoes.
Subsurface drip irrigation has a number of potential advantages over conventional surface irrigation; it curtails weed growth and reduces water loss due to high irrigation uniformity. Depending on a system's design and management, however, it may not always provide adequate soil moisture to germinate the crop seed. This study demonstrates that acceptable levels of seed emergence can be obtained in processing tomatoes using subsurface drip irrigation in clay-loam soil.
San Joaquin River salinity: 1991 projections compared to 1977
by Charles R. Kratzer, Leslie F. Grober
| Full text HTML  | PDF  
At periods of low flow, water quantity and quality at Vernalis depends on how much salt-laden San Joaquin River water is diverted upstream of the Tuolumne.
In the spring of 1991, a water quality model was used to predict flows and salinity in the San Joaquin River for the following summer. It was predicted that the flows and salinities should be more favorable than in 1977, primarily due to improved water quality in the Tuolumne River and increased flows in the Stanislaus River. Actual levels would be largely determined by the amount of diversions from the river.*
Leaf removal in wine grapes: a case study in extending research to the field
by Robert A. Pence, James I. Grieshop
| Full text HTML  | PDF  
Farm advisors helped promote the. wine grape industry's adoption of leaf removal, a practice reducing pesticide use.
Leaf removal reduces pesticide use in California wine grapes. This preliminary study estimates the extent of that reduction and examines some reasons why leaf removal made the successful transition from applied research to production-scale field use.
Imported parasite of greenhouse thrips established on California avocado
by James A. McMurtry, Horace G. Johnson, Sheldon J. Newberger
| Full text HTML  | PDF  
After four growing seasons, a parasite of greenhouse thrips is established and spreading in avocado orchards.
The parasitic wasp, Thripobius semiluteus, introduced for biological control of greenhouse thrips, has been established and spreading for up to four growing seasons at some sites in Southern California avocado orchards. Studies show that declines in thrips numbers coincide with increasing parasitization by this wasp, which could become an important mortality factor of greenhouse thrips if its widespread establishment is achieved.
Owning harvest equipment versus custom hiring: the case of walnuts
by Steven C. Blank, Karen Klonsky, Kim Norris
| Full text HTML  | PDF  
Purchase costs are compared with custom harvest rates to estimate break-even acreage; the latter is weighed against risk.
Is a walnut producer better off owning harvesting equipment or custom hiring someone else to perform the job? This paper compares purchase costs with custom harvest rates, leading to an estimated break-even acreage which can be used as a decision criterion. However, two risk factors must be included in the decision process: the date of harvest and the efficiency of the harvest operation. The effect of these factors may significantly alter the “real” costs of owning versus custom hiring harvest equipment and, therefore, may change the decision reached by an individual grower.
European mistletoe continues to spread in Sonoma County
by Frank G. Hawksworth, Robert F. Scharpf, Melissa Marosy
| Full text HTML  | PDF  
Although European mistletoe has spread in the last 20 years, it is still confined to within 8 miles of its point of introduction.
European mistletoe (Viscum album) was established in Sonoma County about 90 years ago and has spread a maximum of 7.5 miles and an average of 5 miles from its point of introduction in Sebastopol. The mistletoe now occurs in the nearby communities of Graton, Santa Rosa, Fulton, Cotati, Forestville and Occidental. It has been found on 23 different deciduous trees, but is most common on silver maple, apple, black locust, red alder and Fremont cottonwood.

Editorial, News, Letters and Science Briefs

Public literacy about agriculture: What is it? What is it for?
by Nicelma King
Full text HTML  | PDF  
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California Agriculture, Vol. 45, No.6

Loma Vista Farm: learn-by-doing lab for kids
Cover:  On a visit to Loma Vista Farm, Vallejo School district students conduct tests of soil acidity – part of a lesson on sustainable agriculture. Cover photo by Jack Kelly Clark
November-December 1991
Volume 45, Number 6

Peer-reviewed research and review articles

Toxics, food safety, water quality “most important”: How California educators and CE directors view “agricultural literacy” programs
by Marc T. Braverman, Ellen L. Rilla
| Full text HTML  | PDF  
While California'seducational administrators view agricultural literacy as important, new programs must compete for limited classroom resources.
Agricultural literacy programs —now underway in a few California schools — are designed to provide students with a fundamental understanding of how our agricultural system works, including its relationship to natural resources and the environment. In statewide surveys, public school administrators and CE county directors agreed such programs should be incorporated into science or social studies classes during late elementary and middle grades. District administrators identified the most important topics to be toxics in the environment, toxics in the food supply, and water quality and policy. Groups surveyed expressed differing opinions, however, about the plant Of teaching the topic in schools.
Sidebar: Snapshots of current agricultural literacy programs
by Ellen L. Rilla, Daniel J. Desmond, Marc T. Braverman, Richard Ponzio, Faye Lee, Elizabeth Sandlin, Carol Kaney
| Full text HTML  | PDF  
Summary Not Available – First paragraph follows: Site visits to selected schools provided snapshots of agricultural literacy programs across the state. Schools were chosen to represent a wide variety of situations.
Abstract Not Available – First paragraph follows: Site visits to selected schools provided snapshots of agricultural literacy programs across the state. Schools were chosen to represent a wide variety of situations.
New strain of sweetpotato whitefly invades California vegetables
by Thomas M. Perring, Arthur Cooper, Dave J. Kazmer, Clyde Shields, Jon Shields
| Full text HTML  | PDF  
Since 1990, a new strain of sweetpotato whitefly has inflicted heavy damage on vegetable crops statewide.
In 1990, a new strain of sweetpotato whitefly invaded Southern California agricultural regions, inflicting heavy damage on cruciferous crops, Problems related to this new strain have impacted vegetable growers throughout California and other growing regions. In the Imperial Valley, 95% of the 1991 fall melons were disced and total losses to summer and fall crops have been estimated at over $120 million.
Farmworker injury and illness: statistical guides to prevention
by Stephen R. Sutter
| Full text HTML  | PDF  
Farm accident and illness statistics can be used to develop mandated Injury and Illness Prevention Programs.
Requirements mandated by the historic statute Senate Bill 198 include identifying occupational safety and health hazards and training current supervisory and other employees in coping with general agricultural hazards. This review of accident and illness statistics for agriculture may be useful in developing a written Injury and Illness Prevention Program.
Strategies needed for oak protection: Despite landowner favor, oak groves likely to diminish in size and number
by R. H. Schmidt
| Full text HTML  | PDF  
Although landowners report numerous advantages to owning oak groves, strategies are needed to save or replant them.
A survey of landowners in unincorporated parts of Yolo County indicates that they perceive many advantages and few drawbacks to oak-grove ownership. Valley oak acreage is used for farming, wildlife habitat, livestock grazing, houses and outbuildings, and firewood production. However, without new strategies to protect and replace them, existing groves will most likely decrease in size and distribution as properties turn over and new owners and management concerns take over.
Stress-adapted landscapes save water, escape injury in drought
by Roy M. Sachs
| Full text HTML  | PDF  
If adapted to reduced irrigation over a 2-year period, established shrubs and ground covers show no drought-related injury.
Results of investigations at UC experiment stations reveal that irrigation equal to 14% or less of reference evapotranspiration (ETO) can be applied to established shrubs and ground covers with no apparent drought-related injury. Adaptation to stress by reduced irrigation during the 2 years preceding full reduction of irrigation eliminated most injury symptoms (such as wilting and leaf necrosis). Application of these findings to established landscapes should significantly reduce water use and the cost of removing excess vegetation.
Subsurface drip irrigation of tomatoes: Drip system design, management promote seed emergence
by Larry Schwankl, Stephen R. Grattan, Gene M. Miyao
| Full text HTML  | PDF  
Investigators showed that design and management of a drip irrigationsystem could ensure adequate soil moisture for tomatoes.
Subsurface drip irrigation has a number of potential advantages over conventional surface irrigation; it curtails weed growth and reduces water loss due to high irrigation uniformity. Depending on a system's design and management, however, it may not always provide adequate soil moisture to germinate the crop seed. This study demonstrates that acceptable levels of seed emergence can be obtained in processing tomatoes using subsurface drip irrigation in clay-loam soil.
San Joaquin River salinity: 1991 projections compared to 1977
by Charles R. Kratzer, Leslie F. Grober
| Full text HTML  | PDF  
At periods of low flow, water quantity and quality at Vernalis depends on how much salt-laden San Joaquin River water is diverted upstream of the Tuolumne.
In the spring of 1991, a water quality model was used to predict flows and salinity in the San Joaquin River for the following summer. It was predicted that the flows and salinities should be more favorable than in 1977, primarily due to improved water quality in the Tuolumne River and increased flows in the Stanislaus River. Actual levels would be largely determined by the amount of diversions from the river.*
Leaf removal in wine grapes: a case study in extending research to the field
by Robert A. Pence, James I. Grieshop
| Full text HTML  | PDF  
Farm advisors helped promote the. wine grape industry's adoption of leaf removal, a practice reducing pesticide use.
Leaf removal reduces pesticide use in California wine grapes. This preliminary study estimates the extent of that reduction and examines some reasons why leaf removal made the successful transition from applied research to production-scale field use.
Imported parasite of greenhouse thrips established on California avocado
by James A. McMurtry, Horace G. Johnson, Sheldon J. Newberger
| Full text HTML  | PDF  
After four growing seasons, a parasite of greenhouse thrips is established and spreading in avocado orchards.
The parasitic wasp, Thripobius semiluteus, introduced for biological control of greenhouse thrips, has been established and spreading for up to four growing seasons at some sites in Southern California avocado orchards. Studies show that declines in thrips numbers coincide with increasing parasitization by this wasp, which could become an important mortality factor of greenhouse thrips if its widespread establishment is achieved.
Owning harvest equipment versus custom hiring: the case of walnuts
by Steven C. Blank, Karen Klonsky, Kim Norris
| Full text HTML  | PDF  
Purchase costs are compared with custom harvest rates to estimate break-even acreage; the latter is weighed against risk.
Is a walnut producer better off owning harvesting equipment or custom hiring someone else to perform the job? This paper compares purchase costs with custom harvest rates, leading to an estimated break-even acreage which can be used as a decision criterion. However, two risk factors must be included in the decision process: the date of harvest and the efficiency of the harvest operation. The effect of these factors may significantly alter the “real” costs of owning versus custom hiring harvest equipment and, therefore, may change the decision reached by an individual grower.
European mistletoe continues to spread in Sonoma County
by Frank G. Hawksworth, Robert F. Scharpf, Melissa Marosy
| Full text HTML  | PDF  
Although European mistletoe has spread in the last 20 years, it is still confined to within 8 miles of its point of introduction.
European mistletoe (Viscum album) was established in Sonoma County about 90 years ago and has spread a maximum of 7.5 miles and an average of 5 miles from its point of introduction in Sebastopol. The mistletoe now occurs in the nearby communities of Graton, Santa Rosa, Fulton, Cotati, Forestville and Occidental. It has been found on 23 different deciduous trees, but is most common on silver maple, apple, black locust, red alder and Fremont cottonwood.

Editorial, News, Letters and Science Briefs

Public literacy about agriculture: What is it? What is it for?
by Nicelma King
Full text HTML  | PDF  

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