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California Agriculture, Vol. 46, No.5

Most seasonal farm work still goes to new arrivals
Cover:  Despite the intent of the 1986 Immigration Reform and Control Act (IRCA), California farmers continue to rely on new immigrants for most field labor needs. Photo by Jack Kelly Clark
September-October 1992
Volume 46, Number 5

Peer-reviewed research and review articles

Effects of immigration reform not as expected: California farmers still rely on new immigrants for field labor
by J. Edward Taylor, Dawn Thilmany
| Full text HTML  | PDF  
The stable, legal agricultural workforce envisioned by the authors of the 1986 Immigration Reform and Control Act has not materialized; in fact, farmworker turnover is higher now than it was before the law was enacted.
Employer sanctions under the 1986 Immigration Reform and Control Act (IRCA) were intended to encourage US. employers to adjust to a smaller, more legal workforce. This study focuses on changing patterns of farmworker turnover and the use of farm labor contractors to test IRCA's effectiveness. The authors' findings do not support the hypothesis that IRCA would succeed in reducing California agriculture's reliance on new immigrants to meet its labor needs.
Whitefly invasion in Imperial Valley costs growers, workers millions in losses
by Refugio A. Gonzalez, George E. Goldman, Eric T. Natwick, Howard R. Rosenberg, James I. Grieshop, Stephen R. Sutter, Tad Funakoshi, Socorro Davila-Garcia
| Full text HTML  | PDF  
Farmworker unemployment is running high in Imperial County, a by-product of costly infestations of the sweetpotato whitefly in melon and cole crops.
Two years of sweetpotato whitefly infestations in Imperial County have resulted in huge losses to growers of melons and Cole crops and in high unemployment among farmworkers. The economic impact on the county is analyzed here.
Cracks in irrigated clay soil may allow some drainage
by Mark E. Grismer
| Full text HTML  | PDF  
An understanding of the nature of soil cracks appearing in clay soils after irrigation can help engineers improve irrigation and drainage systems.
Cracking clay soil poses unique water management problems. Typically, clay soil is presumed to have negligible drainable pore space. Field measurements, however, suggest that there may be as much as 10% drainable pore space available, due in part to soil cracking. Such pore space may be useful in designing irrigation-drainage systems for these soils.
Pay method affects vineyard pruner performance
by Gregory E. Billikopf, Maxwell V. Norton
| Full text HTML  | PDF  
Workers paid at a piece rate tend to prune more quickly, but the perceived quality of pruning may be slightly higher when workers are paid by the hour.
A new study indicates that vineyard pruners paid on a piece-rate basis tend to work more quickly than those paid by the hour. Pay method had little effect on pruning quality as perceived by growers, although crews paid by the hour did seem to do a slightly better job. Total pruning costs were also influenced by vine vigor and vineyard location.
Income risk varies with what you grow, where you grow it
by Steven C. Blank
| Full text HTML  | PDF  
Profits vary widely across agricultural markets, and today's bankers want to know all about these risks. A new study may help producers choose what to grow and how to apply for credit.
Farmers seeking credit today are up against a lending “crunch” that is forcing them to re-assess what they grow and where they grow it. To assist those looking for new market opportunities, a new study offers ways of calculating the kinds of financial risks that concern the lenders who read today's credit applications.
“Residue-free” tomatoes? Bush tomatoes show very low levels of pesticide residues
by Frank V. Sances, Nick C. Toscano, Lyle K. Gaston
| Full text HTML  | PDF  
Current postharvest practices eliminate nearly all pesticide residues - which are few to begin with - on market tomatoes, research shows.
Do pesticide residues persist on bush tomatoes? Apparently not — or at least not much, according to a new study. When fruit was treated directly, then washed and brushed during normal postharvest handling, most — if not all — chemical residues were reduced by 50 to 95%. Extensive sampling at commercial packing facilities showed no detectable residues.
Before-and-after tests on emitters show organic fertilizers can be injected through low-volume irrigation systems
by Lawrence J. Schwankl, Glenn McGourty
| Full text HTML  | PDF  
Growers often hesitate to inject organic fertilizers into drip systems for fear of causing clogs, but here are two organics that work well with a variety of emitters.
The practice of injecting organic fertilizers into low-volume irrigation systems is not widespread, partly because of concerns that the materials will clog emitters. This study looks at two spray-dried organic fertilizers (fish protein and poultry protein) that were injected through various low-volume irrigation systems, and finds only minimal clogging and even distribution of fertilizer throughout the irrigated area.
Cost comparison: engines vs. electric motors for irrigation pumping
by Robert G. Curley, Gerald D. Knutson
| Full text HTML  | PDF  
Energy costs for irrigation pumping have increased in recent years, pushing up total farm costs. Growers can now use a computer program from UC to compare the potential costs of different power units.
Farmers may save money in the long run by switching from electric to diesel, natural gas, or propane-powered irrigation pumps, but fuel cost trends are hard to predict. A new computer program can help growers compare potential costs of all four irrigation power sources.
Gophers love oak — to death
by Theodore E. Adams, William H. Weitkamp
| Full text HTML  | PDF  
In the absence of poison baits, physical barriers can effectively prevent gopher predation on young oak trees, thus improving the chances of oak regeneration.
Weed competition, insects, and small mammals all account for oak seedling loss. High populations of pocket gophers, as at Lopez Lake County Park in San Luis Obispo County, can destroy 90% of 2 to 3-month-old transplanted valley oak seedlings in the first year. Without effective protection from pocket gophers, any control of or protection from other small mammals and control of competition may be of little value
Environmental factors contribute to acorn quality: Elevation, on- or off-tree collection influence the viability of blue oak acorns
by Ralph L. Phillips
| Full text HTML  | PDF  
Local conditions affect the size and moisture content of blue oak and valley oak acorns, making some more susceptible to fungal or insect damage that can interfere with germination and growth.
Concern about the regeneration of California's native oaks has inspired several investigations that indicate acorn quality is one of many factors affecting regeneration. A survey conducted in Kern County in 7990 indicates that elevation influences blue oak and valley oak acorn quality; location with regard to water drainage is another factor for blue oak acorns.

Editorial, News, Letters and Science Briefs

Food safety: a matter of fact
by John E. Kinsella
Full text HTML  | PDF  
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California Agriculture, Vol. 46, No.5

Most seasonal farm work still goes to new arrivals
Cover:  Despite the intent of the 1986 Immigration Reform and Control Act (IRCA), California farmers continue to rely on new immigrants for most field labor needs. Photo by Jack Kelly Clark
September-October 1992
Volume 46, Number 5

Peer-reviewed research and review articles

Effects of immigration reform not as expected: California farmers still rely on new immigrants for field labor
by J. Edward Taylor, Dawn Thilmany
| Full text HTML  | PDF  
The stable, legal agricultural workforce envisioned by the authors of the 1986 Immigration Reform and Control Act has not materialized; in fact, farmworker turnover is higher now than it was before the law was enacted.
Employer sanctions under the 1986 Immigration Reform and Control Act (IRCA) were intended to encourage US. employers to adjust to a smaller, more legal workforce. This study focuses on changing patterns of farmworker turnover and the use of farm labor contractors to test IRCA's effectiveness. The authors' findings do not support the hypothesis that IRCA would succeed in reducing California agriculture's reliance on new immigrants to meet its labor needs.
Whitefly invasion in Imperial Valley costs growers, workers millions in losses
by Refugio A. Gonzalez, George E. Goldman, Eric T. Natwick, Howard R. Rosenberg, James I. Grieshop, Stephen R. Sutter, Tad Funakoshi, Socorro Davila-Garcia
| Full text HTML  | PDF  
Farmworker unemployment is running high in Imperial County, a by-product of costly infestations of the sweetpotato whitefly in melon and cole crops.
Two years of sweetpotato whitefly infestations in Imperial County have resulted in huge losses to growers of melons and Cole crops and in high unemployment among farmworkers. The economic impact on the county is analyzed here.
Cracks in irrigated clay soil may allow some drainage
by Mark E. Grismer
| Full text HTML  | PDF  
An understanding of the nature of soil cracks appearing in clay soils after irrigation can help engineers improve irrigation and drainage systems.
Cracking clay soil poses unique water management problems. Typically, clay soil is presumed to have negligible drainable pore space. Field measurements, however, suggest that there may be as much as 10% drainable pore space available, due in part to soil cracking. Such pore space may be useful in designing irrigation-drainage systems for these soils.
Pay method affects vineyard pruner performance
by Gregory E. Billikopf, Maxwell V. Norton
| Full text HTML  | PDF  
Workers paid at a piece rate tend to prune more quickly, but the perceived quality of pruning may be slightly higher when workers are paid by the hour.
A new study indicates that vineyard pruners paid on a piece-rate basis tend to work more quickly than those paid by the hour. Pay method had little effect on pruning quality as perceived by growers, although crews paid by the hour did seem to do a slightly better job. Total pruning costs were also influenced by vine vigor and vineyard location.
Income risk varies with what you grow, where you grow it
by Steven C. Blank
| Full text HTML  | PDF  
Profits vary widely across agricultural markets, and today's bankers want to know all about these risks. A new study may help producers choose what to grow and how to apply for credit.
Farmers seeking credit today are up against a lending “crunch” that is forcing them to re-assess what they grow and where they grow it. To assist those looking for new market opportunities, a new study offers ways of calculating the kinds of financial risks that concern the lenders who read today's credit applications.
“Residue-free” tomatoes? Bush tomatoes show very low levels of pesticide residues
by Frank V. Sances, Nick C. Toscano, Lyle K. Gaston
| Full text HTML  | PDF  
Current postharvest practices eliminate nearly all pesticide residues - which are few to begin with - on market tomatoes, research shows.
Do pesticide residues persist on bush tomatoes? Apparently not — or at least not much, according to a new study. When fruit was treated directly, then washed and brushed during normal postharvest handling, most — if not all — chemical residues were reduced by 50 to 95%. Extensive sampling at commercial packing facilities showed no detectable residues.
Before-and-after tests on emitters show organic fertilizers can be injected through low-volume irrigation systems
by Lawrence J. Schwankl, Glenn McGourty
| Full text HTML  | PDF  
Growers often hesitate to inject organic fertilizers into drip systems for fear of causing clogs, but here are two organics that work well with a variety of emitters.
The practice of injecting organic fertilizers into low-volume irrigation systems is not widespread, partly because of concerns that the materials will clog emitters. This study looks at two spray-dried organic fertilizers (fish protein and poultry protein) that were injected through various low-volume irrigation systems, and finds only minimal clogging and even distribution of fertilizer throughout the irrigated area.
Cost comparison: engines vs. electric motors for irrigation pumping
by Robert G. Curley, Gerald D. Knutson
| Full text HTML  | PDF  
Energy costs for irrigation pumping have increased in recent years, pushing up total farm costs. Growers can now use a computer program from UC to compare the potential costs of different power units.
Farmers may save money in the long run by switching from electric to diesel, natural gas, or propane-powered irrigation pumps, but fuel cost trends are hard to predict. A new computer program can help growers compare potential costs of all four irrigation power sources.
Gophers love oak — to death
by Theodore E. Adams, William H. Weitkamp
| Full text HTML  | PDF  
In the absence of poison baits, physical barriers can effectively prevent gopher predation on young oak trees, thus improving the chances of oak regeneration.
Weed competition, insects, and small mammals all account for oak seedling loss. High populations of pocket gophers, as at Lopez Lake County Park in San Luis Obispo County, can destroy 90% of 2 to 3-month-old transplanted valley oak seedlings in the first year. Without effective protection from pocket gophers, any control of or protection from other small mammals and control of competition may be of little value
Environmental factors contribute to acorn quality: Elevation, on- or off-tree collection influence the viability of blue oak acorns
by Ralph L. Phillips
| Full text HTML  | PDF  
Local conditions affect the size and moisture content of blue oak and valley oak acorns, making some more susceptible to fungal or insect damage that can interfere with germination and growth.
Concern about the regeneration of California's native oaks has inspired several investigations that indicate acorn quality is one of many factors affecting regeneration. A survey conducted in Kern County in 7990 indicates that elevation influences blue oak and valley oak acorn quality; location with regard to water drainage is another factor for blue oak acorns.

Editorial, News, Letters and Science Briefs

Food safety: a matter of fact
by John E. Kinsella
Full text HTML  | PDF  

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