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California Agriculture, Vol. 45, No.2

Can farmers use water more effectively? Irrigation systems compared
Cover:  Canal Near Davis ca. 1967, University of California, Davis. California Museum of Photography Sweeney and Rubin Ansel Adams Fiat Lux collection, University of Caalifornia, Riverside. The photograph is one of the Fiat Lux collection depicting diverse facets of University of California life. UC's agricultural research has been a mainstay of its scientific enterprise for more tham a century.
March-April 1991
Volume 45, Number 2

Peer-reviewed research and review articles

Can farmers use water more effectively?: Two on-farm demonstrations compare irrigation methods
by Editors
| Full text HTML  | PDF  
Two reports describe on-farm demonstrations designed to reduce drainwater while maximizing net return. Undertaken at two locations, they yielded different results. An interpretative analysis follows the reports.
High water tables and associated high salinity now hamper farm production across 400,000 acres of farmland in Fresno, Kings, Tulare and Kern Counties in the San Joaquin Valley. The two following reports describe farm demonstration projects undertaken to reduce drainwater volume while maintaining profitability. Performed at different sites under differing conditions, the projects yielded different results. An analysis of the combined results appears on page 11. (Ed.)
Reducing drainwater: Furrow vs. subsurface drip irrigation
by Allan E. Fulton, J. D. Oster, Blaine R. Hanson, Claude J. Phene, David A. Goldhamer
| Full text HTML  | PDF  
Shortening furrow length by one-half and set time by more than one-half proved the most economical method of reducina drainaae.
Cotton was produced using conventional furrow irrigation, an upgraded continuous-flow furrow design, surge irrigation, and subsurface drlp lrrlgatlon in 1987 and 1988. We found that the most economical method of reducing potential drainage at this site was to reduce the furrow length by half and decrease the set time by more than one-half during preirrigation. A subsurface drip system reduced potential drainage most effectively and increased production, but caused an overall profit loss. Subsurface drip systems may be profitable if properly designed and managed; however, a substantial yield increase or reduction in drainage disposal costs must be achieved. Otherwise, profitability of subsurface drip would be less than that for furrow irrigation systems.
Subsurface drip produced highest net return in Westlands area study
by Richard B. Smith, J. D. Oster, Claude Phene
| Full text HTML  | PDF  
Net profits from drip-irrigated cotton fields exceeded those from furrow-irrigated acres.
Cotton was produced using subsurface drip, low-energy precision application (LEPA), scheduled furrow, and conventional furrow irrigation systems in 1989. Subsurface drip irrigation produced the highest net return to the grower through increased cotton yields. Significant water conservation was achieved with both pressurized irrigation systems (subsurface drip and LEPA). However, computer aided scheduling of furrow irrigation did not result in significant water savings. Pressurized irrigation systems may offer the flexibility and control necessary to significantly limit unnecessary water additions to the shallow groundwater table.
Analysis: Demonstration projects compared
by Richard B. Smith, J. D. Oster
| Full text HTML  | PDF  
Conditions such as the depth of saline water tables may account for different results in the irrigation studies.
In this discussion of the two projects and their different results, the Five Points project is denoted as DWR, for the sponsoring California Department of Water Resources, and the Stratford project is denoted as UC, for the sponsoring UC Salinity and Drainage Task Force. (Ed.)
South Sierra oak regeneration wak in sapling stage
by Richard Standiford, Neil McDougald, Ralph Phillips, Aaron Nelson
| Full text HTML  | PDF  
Oak seedlings at lower elevations have more difficulty reaching maturity and replacing older trees as they die or are harvested.
A recent survey of oak regeneration in four southern Sierra counties found sufficient regeneration of seedlings, but a general shortage of pole-size trees. Managers will need to find ways to encourage oak seedling recruitment into the pole-size class to ensure sustainable oak woodland stands.
How quality relates to price in California fresh peaches
by Douglas D. Parker, David Zilberman, Kirby Moulton
| Full text HTML  | PDF  
Consumers will pay more for sweeter, more mature peaches, and producers could gain by developing an appropriate price structure.
During a single season, researchers compared California fresh peaches for quality and price at the producer and retail levels. While prices at both levels declined during the season, they responded differently to changes in quality characteristics. The results suggest a potential for increased revenues from marketing sweeter, more mature fruit.
Trace elements limit potential for blending San Joaquin drainwater with canal water
by Blaine R. Hanson, Wilbur Bowers, Stephen R. Grattan, Donald W. Grimes, Kenneth K. Tanji
| Full text HTML  | PDF  
Boron and molybdenum in westside drainwater limit its usefulness as a blending agent to increase infiltration rates of eastside canal Water.
Poor soil-water infiltration in the eastside of the San Joaquin Valley is frequently attributed to low-salinity irrigation water. This report assesses the feasibility of improving infiltration rates by blending the more saline westside drainwater with the less saline FriantKern Canal water, a strategy which would also provide a disposal method for westside drain water. However, the study found that boron and molybdenum concentrations in the drainwaters require large blending ratios to prevent crop yield reductions of tree crops grown along the eastside. These large blending ratios mean that the blended irrigation water may have little effect on improving filtration.
Low-input technology proves viable for limited-resource farmers in Salinas Valley
by Miguel A. Altieri, Javier A. Trujillo, Marta A. Astier, Paul L. Gersper, Wilhelmus A. Bakx
| Full text HTML  | PDF  
Small farmers team with UC researchers to develop cost-effective techniques.
Low-input farming techniques offered energy-saving, cost-effective alternatives for resource-poor farmers of Mexican origin in the Salinas Valley. Most of these farmers currently manage small acreages using intensive vegetable cropping systems and high-input technologies.
Treatment of destructive elm leaf beetle should be timed by temperature
by Steve H. Dreistadt, Donald L. Dahlsten, David L. Rowney, Susan M. Tait, Glen Y. Yokota, William A. Copper
| Full text HTML  | PDF  
Control of the destructive beetle can be effectively timed by monitoring daily temperatures.
Elm leaf beetle control efforts in northern California can be effectively timed using temperature monitoring. Two available control methods are a new biological insecticide, and an insecticide applied as a bark band. Both methods help preserve the beetle's natural enemies.
To control mealybugs, stop honeydew-seeking ants
by Phil A. Phillips, Cindy J. Sherk
| Full text HTML  | PDF  
Effective ant control can reduce infestations of obscure mealybug in coastal vineyards.
Recent increases in obscure mealybug infestations in central-coast vineyards have been associated with Argentine ant activity. Mealybug infestations were reduced by controlling these honeydew-seeking ants in the spring, using chemical treatments directed at the base of the vines. This control strategy avoids full coverage treatments disruptive to bene ficials.
If registered, fungicide could reduce cavity spot of carrots
by R. Michael Davis, Joe J. Nuñez, John P. Guerard, Elisabetta Vivoda
| Full text HTML  | PDF  
The authors have found a fungicide that, if registered, can significantly reduce crop losses to this disease.
No control measures are now available for reducing losses to cavity spot, the most damaging carrot disease in California. Researchers have found a fungicide that provides excellent control of the disease, though it is not yet registered for use on carrots.
Phylloxera on rise…: Deadly insect pest poses increased risk to north coast vineyards
by Jeffrey Granett, John A. De Benedictis, James A. Wolpert, Edward Weber, Austin C. Goheen
| Full text HTML  | PDF  
The widely-planted grape rootstock AxR#l is no longer suitable for California.
Resistant rootstocks protect grape vines from phylloxera; however, a new form of this insect, Biotype B, threatens the survival of 70% of Napa and Sonoma County vineyards, those which are planted on the rootstock AxR#1. Research demonstrates that different accessions of AxR#l are equally susceptible to damage by this insect, a form of plant lice. The insect has spread from two sites in 1983 to more than 70 sites in those two counties; spread to other grapegrowing counties is likely.

Editorial, News, Letters and Science Briefs

Publicly funded agricultural research: An impending crisis?
by Kenneth R. Farrell
Full text HTML  | PDF  
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California Agriculture, Vol. 45, No.2

Can farmers use water more effectively? Irrigation systems compared
Cover:  Canal Near Davis ca. 1967, University of California, Davis. California Museum of Photography Sweeney and Rubin Ansel Adams Fiat Lux collection, University of Caalifornia, Riverside. The photograph is one of the Fiat Lux collection depicting diverse facets of University of California life. UC's agricultural research has been a mainstay of its scientific enterprise for more tham a century.
March-April 1991
Volume 45, Number 2

Peer-reviewed research and review articles

Can farmers use water more effectively?: Two on-farm demonstrations compare irrigation methods
by Editors
| Full text HTML  | PDF  
Two reports describe on-farm demonstrations designed to reduce drainwater while maximizing net return. Undertaken at two locations, they yielded different results. An interpretative analysis follows the reports.
High water tables and associated high salinity now hamper farm production across 400,000 acres of farmland in Fresno, Kings, Tulare and Kern Counties in the San Joaquin Valley. The two following reports describe farm demonstration projects undertaken to reduce drainwater volume while maintaining profitability. Performed at different sites under differing conditions, the projects yielded different results. An analysis of the combined results appears on page 11. (Ed.)
Reducing drainwater: Furrow vs. subsurface drip irrigation
by Allan E. Fulton, J. D. Oster, Blaine R. Hanson, Claude J. Phene, David A. Goldhamer
| Full text HTML  | PDF  
Shortening furrow length by one-half and set time by more than one-half proved the most economical method of reducina drainaae.
Cotton was produced using conventional furrow irrigation, an upgraded continuous-flow furrow design, surge irrigation, and subsurface drlp lrrlgatlon in 1987 and 1988. We found that the most economical method of reducing potential drainage at this site was to reduce the furrow length by half and decrease the set time by more than one-half during preirrigation. A subsurface drip system reduced potential drainage most effectively and increased production, but caused an overall profit loss. Subsurface drip systems may be profitable if properly designed and managed; however, a substantial yield increase or reduction in drainage disposal costs must be achieved. Otherwise, profitability of subsurface drip would be less than that for furrow irrigation systems.
Subsurface drip produced highest net return in Westlands area study
by Richard B. Smith, J. D. Oster, Claude Phene
| Full text HTML  | PDF  
Net profits from drip-irrigated cotton fields exceeded those from furrow-irrigated acres.
Cotton was produced using subsurface drip, low-energy precision application (LEPA), scheduled furrow, and conventional furrow irrigation systems in 1989. Subsurface drip irrigation produced the highest net return to the grower through increased cotton yields. Significant water conservation was achieved with both pressurized irrigation systems (subsurface drip and LEPA). However, computer aided scheduling of furrow irrigation did not result in significant water savings. Pressurized irrigation systems may offer the flexibility and control necessary to significantly limit unnecessary water additions to the shallow groundwater table.
Analysis: Demonstration projects compared
by Richard B. Smith, J. D. Oster
| Full text HTML  | PDF  
Conditions such as the depth of saline water tables may account for different results in the irrigation studies.
In this discussion of the two projects and their different results, the Five Points project is denoted as DWR, for the sponsoring California Department of Water Resources, and the Stratford project is denoted as UC, for the sponsoring UC Salinity and Drainage Task Force. (Ed.)
South Sierra oak regeneration wak in sapling stage
by Richard Standiford, Neil McDougald, Ralph Phillips, Aaron Nelson
| Full text HTML  | PDF  
Oak seedlings at lower elevations have more difficulty reaching maturity and replacing older trees as they die or are harvested.
A recent survey of oak regeneration in four southern Sierra counties found sufficient regeneration of seedlings, but a general shortage of pole-size trees. Managers will need to find ways to encourage oak seedling recruitment into the pole-size class to ensure sustainable oak woodland stands.
How quality relates to price in California fresh peaches
by Douglas D. Parker, David Zilberman, Kirby Moulton
| Full text HTML  | PDF  
Consumers will pay more for sweeter, more mature peaches, and producers could gain by developing an appropriate price structure.
During a single season, researchers compared California fresh peaches for quality and price at the producer and retail levels. While prices at both levels declined during the season, they responded differently to changes in quality characteristics. The results suggest a potential for increased revenues from marketing sweeter, more mature fruit.
Trace elements limit potential for blending San Joaquin drainwater with canal water
by Blaine R. Hanson, Wilbur Bowers, Stephen R. Grattan, Donald W. Grimes, Kenneth K. Tanji
| Full text HTML  | PDF  
Boron and molybdenum in westside drainwater limit its usefulness as a blending agent to increase infiltration rates of eastside canal Water.
Poor soil-water infiltration in the eastside of the San Joaquin Valley is frequently attributed to low-salinity irrigation water. This report assesses the feasibility of improving infiltration rates by blending the more saline westside drainwater with the less saline FriantKern Canal water, a strategy which would also provide a disposal method for westside drain water. However, the study found that boron and molybdenum concentrations in the drainwaters require large blending ratios to prevent crop yield reductions of tree crops grown along the eastside. These large blending ratios mean that the blended irrigation water may have little effect on improving filtration.
Low-input technology proves viable for limited-resource farmers in Salinas Valley
by Miguel A. Altieri, Javier A. Trujillo, Marta A. Astier, Paul L. Gersper, Wilhelmus A. Bakx
| Full text HTML  | PDF  
Small farmers team with UC researchers to develop cost-effective techniques.
Low-input farming techniques offered energy-saving, cost-effective alternatives for resource-poor farmers of Mexican origin in the Salinas Valley. Most of these farmers currently manage small acreages using intensive vegetable cropping systems and high-input technologies.
Treatment of destructive elm leaf beetle should be timed by temperature
by Steve H. Dreistadt, Donald L. Dahlsten, David L. Rowney, Susan M. Tait, Glen Y. Yokota, William A. Copper
| Full text HTML  | PDF  
Control of the destructive beetle can be effectively timed by monitoring daily temperatures.
Elm leaf beetle control efforts in northern California can be effectively timed using temperature monitoring. Two available control methods are a new biological insecticide, and an insecticide applied as a bark band. Both methods help preserve the beetle's natural enemies.
To control mealybugs, stop honeydew-seeking ants
by Phil A. Phillips, Cindy J. Sherk
| Full text HTML  | PDF  
Effective ant control can reduce infestations of obscure mealybug in coastal vineyards.
Recent increases in obscure mealybug infestations in central-coast vineyards have been associated with Argentine ant activity. Mealybug infestations were reduced by controlling these honeydew-seeking ants in the spring, using chemical treatments directed at the base of the vines. This control strategy avoids full coverage treatments disruptive to bene ficials.
If registered, fungicide could reduce cavity spot of carrots
by R. Michael Davis, Joe J. Nuñez, John P. Guerard, Elisabetta Vivoda
| Full text HTML  | PDF  
The authors have found a fungicide that, if registered, can significantly reduce crop losses to this disease.
No control measures are now available for reducing losses to cavity spot, the most damaging carrot disease in California. Researchers have found a fungicide that provides excellent control of the disease, though it is not yet registered for use on carrots.
Phylloxera on rise…: Deadly insect pest poses increased risk to north coast vineyards
by Jeffrey Granett, John A. De Benedictis, James A. Wolpert, Edward Weber, Austin C. Goheen
| Full text HTML  | PDF  
The widely-planted grape rootstock AxR#l is no longer suitable for California.
Resistant rootstocks protect grape vines from phylloxera; however, a new form of this insect, Biotype B, threatens the survival of 70% of Napa and Sonoma County vineyards, those which are planted on the rootstock AxR#1. Research demonstrates that different accessions of AxR#l are equally susceptible to damage by this insect, a form of plant lice. The insect has spread from two sites in 1983 to more than 70 sites in those two counties; spread to other grapegrowing counties is likely.

Editorial, News, Letters and Science Briefs

Publicly funded agricultural research: An impending crisis?
by Kenneth R. Farrell
Full text HTML  | PDF  

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