California Agriculture
California Agriculture
California Agriculture
University of California
California Agriculture

Archive

January-February 1990
Volume 44, Number 1

Peer-reviewed research and review articles

Biological control sought for ash whitefly
by Tom S. Bellows, Timothy D. Paine, Ken Y. Arakawa, Carol Meisenbacher, Paula Leddy, John Kabashima
| Full text HTML  | PDF  
Dense populations of winged adults (about 1.5 mm in length or the thickness of a penny) and nymphal stages of ash whitefly cover foliage, producing large amounts of honeydew (the clear droplet in cover photo). The whiteflies feed on ash and other ornamental trees and a wide range of fruit trees. Large infestations have been troublesome since first reported in southern California in 1988, and ash whitefly has spread both north and south since. (Cover photo by Jack Kelly Clark)
Ash whitefly has spread over a large portion of California since the initial infestation was discovered in Los Angeles County in 1988. Populations have grown to high densities on a wide range of host plants, including ash, pear, apple, citrus, and other landscape and fruit trees. The best hope for control appears to be natural enemies: a parasitic wasp and a predatory beetle have been introduced and are being evaluated.
Harvesting eucalyptus for fuel chips
by Bruce R. Hartsough, Gary Nakamura
| Full text HTML  | PDF  
Size of trees, acreage cut, and distance from the power plant using the chips have a big effect on costs.
Six-year-old eucalyptus trees were harvested, chipped, and delivered to an electric power plant. Costs exceeded the value of the chips. Expenses could be reduced if bigger trees were harvested, more acres were cut, and the stand were closer to the power plant.
Distribution of peach twig borer damage in peaches
by Craig V. Weakley, Philipp Kirsch, Frank G. Zalorn
| Full text HTML  | PDF  
Fruit damage was greatest on the last sampling date and was concentrated in the tops of trees in orchard edge rows.
Damage to fruit by the peach twig borer was greatest late in the season and in the tops of trees at the orchard edges. Monitoring for damage should begin at least 4 weeks before harvest.
Walnut dehydrators vary in performance
by Joseph A. Grant, James F. Thompson
| Full text HTML  | PDF  
Samples from the tops and bottoms of bins of 11 dehydrators showed that many tended to overdry walnuts.
Samples from 11 walnut dehydrators in San Joaquin County showed substantial over drying. Using grain moisture meters helps, but more accurate, faster methods are needed to test moisture of nuts throughout the bin.
Sweet sorghum cuItivars for alcohol production
by F.J. Hills, R. T. Lewellen, I.O. Skoyen
| Full text HTML  | PDF  
Many cultivars would do well in much of California, with a potential production of up to 575 gallons of ethanol per acre.
Sweet sorghum does well in much of California. Cultivars were tested that showed a potential for producing from 475 to 575 gallons of ethanol per acre.
Clogging of buried drip irrigation systems
by Larry J. Schwankl, Terry L. Prichard
| Full text HTML  | PDF  
ESI-50,a phosphonate, was as effective as acid in controlling chemical precipitate clogging in two field tests.
Lime precipitate clogging of buried drip irrigation systems is difficult to detect and can cause problems where water quality is poor. Injecting a phosphonate was as effective as acid against clogging in two field trials, and may cost less.
Treatment timing defined for Egyptian alfalfa weevil in the high desert
by Vernon M. Stern, Steve B. Orloff
| Full text HTML  | PDF  
Treatment soon after winter regrowth began, rather than later, produced higher yields in Mojave Desert alfalfa.
Profits were highest in Mojave Desert alfalfa when treatment for Egyptian alfalfa weevil was applied soon after winter plant regrowth began and leaf damage was present on new stems.
Parasitoid helps control fruit worm in Sacramento Valley processing tomatoes
by Michael P. Hoffmann, Lloyd T. Wilson, Frank G. Zalom, Richard J. Hilton, Craig V. Weakley
| Full text HTML  | PDF  
The parasitic wasp Trichogramma provides important natural control of the to- mato fruitworm in the valley.
Naturally occurring populations of the parasitic wasp Trichogramma help control the tomato fruit worm in processing tomatoes grown in the Sacramento Valley. Incorporating this factor into the pest management decision-making process should reduce insecticide applications needed to control the pest.
Immigration reform and California agriculture a year later
by Philip L. Martin, J. Edward Taylor
| Full text HTML  | PDF  
A February 1989 survey of California farm employers suggests they are not yet adjusting to the Immigration Reform and Control Act of 1986. Instead of revising their personnel policies to retain newly legalized farm workers, farmers expect to hire more workers through labor contractors if the seasonal work force shrinks.
A February 1989 survey indicated the 1986 law had not yet affected crop production, wages, or employment.
Stable fly and house fly breeding sites on dairies
by Jeffery A. Meyer, Thomas A. Shultz
| Full text HTML  | PDF  
Differing management practices in central and southern California affect breeding sites, but sanitation is a key.
Variations in management practices on dairies in central and southern California have resulted in some differences in fly breeding sites. Sanitation will have to be a focus of fly control efforts in the future on all dairies.
Cultural management of bluetongue virus vectors
by Bradley A. Mullens, John L. Rodriguez
| Full text HTML  | PDF  
Dairy wastewater pond design and management affect numbers of blood-feeding gnats that spread bluetongue virus.
Surveys and experiments in dairy wastewater ponds showed that pond design and management affect populations of blood-feeding gnats that spread bluetongue virus. A voiding shallow evaporation beds, changing water levels weekly, and keeping manure pollution below 300 to 400 milligrams COD per liter will help control gnats.
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January-February 1990
Volume 44, Number 1

Peer-reviewed research and review articles

Biological control sought for ash whitefly
by Tom S. Bellows, Timothy D. Paine, Ken Y. Arakawa, Carol Meisenbacher, Paula Leddy, John Kabashima
| Full text HTML  | PDF  
Dense populations of winged adults (about 1.5 mm in length or the thickness of a penny) and nymphal stages of ash whitefly cover foliage, producing large amounts of honeydew (the clear droplet in cover photo). The whiteflies feed on ash and other ornamental trees and a wide range of fruit trees. Large infestations have been troublesome since first reported in southern California in 1988, and ash whitefly has spread both north and south since. (Cover photo by Jack Kelly Clark)
Ash whitefly has spread over a large portion of California since the initial infestation was discovered in Los Angeles County in 1988. Populations have grown to high densities on a wide range of host plants, including ash, pear, apple, citrus, and other landscape and fruit trees. The best hope for control appears to be natural enemies: a parasitic wasp and a predatory beetle have been introduced and are being evaluated.
Harvesting eucalyptus for fuel chips
by Bruce R. Hartsough, Gary Nakamura
| Full text HTML  | PDF  
Size of trees, acreage cut, and distance from the power plant using the chips have a big effect on costs.
Six-year-old eucalyptus trees were harvested, chipped, and delivered to an electric power plant. Costs exceeded the value of the chips. Expenses could be reduced if bigger trees were harvested, more acres were cut, and the stand were closer to the power plant.
Distribution of peach twig borer damage in peaches
by Craig V. Weakley, Philipp Kirsch, Frank G. Zalorn
| Full text HTML  | PDF  
Fruit damage was greatest on the last sampling date and was concentrated in the tops of trees in orchard edge rows.
Damage to fruit by the peach twig borer was greatest late in the season and in the tops of trees at the orchard edges. Monitoring for damage should begin at least 4 weeks before harvest.
Walnut dehydrators vary in performance
by Joseph A. Grant, James F. Thompson
| Full text HTML  | PDF  
Samples from the tops and bottoms of bins of 11 dehydrators showed that many tended to overdry walnuts.
Samples from 11 walnut dehydrators in San Joaquin County showed substantial over drying. Using grain moisture meters helps, but more accurate, faster methods are needed to test moisture of nuts throughout the bin.
Sweet sorghum cuItivars for alcohol production
by F.J. Hills, R. T. Lewellen, I.O. Skoyen
| Full text HTML  | PDF  
Many cultivars would do well in much of California, with a potential production of up to 575 gallons of ethanol per acre.
Sweet sorghum does well in much of California. Cultivars were tested that showed a potential for producing from 475 to 575 gallons of ethanol per acre.
Clogging of buried drip irrigation systems
by Larry J. Schwankl, Terry L. Prichard
| Full text HTML  | PDF  
ESI-50,a phosphonate, was as effective as acid in controlling chemical precipitate clogging in two field tests.
Lime precipitate clogging of buried drip irrigation systems is difficult to detect and can cause problems where water quality is poor. Injecting a phosphonate was as effective as acid against clogging in two field trials, and may cost less.
Treatment timing defined for Egyptian alfalfa weevil in the high desert
by Vernon M. Stern, Steve B. Orloff
| Full text HTML  | PDF  
Treatment soon after winter regrowth began, rather than later, produced higher yields in Mojave Desert alfalfa.
Profits were highest in Mojave Desert alfalfa when treatment for Egyptian alfalfa weevil was applied soon after winter plant regrowth began and leaf damage was present on new stems.
Parasitoid helps control fruit worm in Sacramento Valley processing tomatoes
by Michael P. Hoffmann, Lloyd T. Wilson, Frank G. Zalom, Richard J. Hilton, Craig V. Weakley
| Full text HTML  | PDF  
The parasitic wasp Trichogramma provides important natural control of the to- mato fruitworm in the valley.
Naturally occurring populations of the parasitic wasp Trichogramma help control the tomato fruit worm in processing tomatoes grown in the Sacramento Valley. Incorporating this factor into the pest management decision-making process should reduce insecticide applications needed to control the pest.
Immigration reform and California agriculture a year later
by Philip L. Martin, J. Edward Taylor
| Full text HTML  | PDF  
A February 1989 survey of California farm employers suggests they are not yet adjusting to the Immigration Reform and Control Act of 1986. Instead of revising their personnel policies to retain newly legalized farm workers, farmers expect to hire more workers through labor contractors if the seasonal work force shrinks.
A February 1989 survey indicated the 1986 law had not yet affected crop production, wages, or employment.
Stable fly and house fly breeding sites on dairies
by Jeffery A. Meyer, Thomas A. Shultz
| Full text HTML  | PDF  
Differing management practices in central and southern California affect breeding sites, but sanitation is a key.
Variations in management practices on dairies in central and southern California have resulted in some differences in fly breeding sites. Sanitation will have to be a focus of fly control efforts in the future on all dairies.
Cultural management of bluetongue virus vectors
by Bradley A. Mullens, John L. Rodriguez
| Full text HTML  | PDF  
Dairy wastewater pond design and management affect numbers of blood-feeding gnats that spread bluetongue virus.
Surveys and experiments in dairy wastewater ponds showed that pond design and management affect populations of blood-feeding gnats that spread bluetongue virus. A voiding shallow evaporation beds, changing water levels weekly, and keeping manure pollution below 300 to 400 milligrams COD per liter will help control gnats.

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