California Agriculture
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California Agriculture, Vol. 56, No.3

A warmer California: Assessing the impacts of climate change
Cover:  A new sensor orbiting the Earth aboard NASA's Terra satellite is collecting the most detailed measurements ever made of the sea's surface temperature. The Moderate-resolution Imaging Spectro-radiometer (MODIS) is measuring sea surface temperature at twice the accuracy of previous satellites. Taken Jan. 1-8, 2001, this image shows cold water upwelling near the coast of Peru, and joining the South Equatorial Current, which flows westward across the Pacific Ocean. Thermal expnasion of seawater and widespread loss of land ice due to global warming have very lilely contributed to the documented rise on sea level (1 to 2 millimeters annually) during the 20th century. Image by Jesse Allen, based on data provided by the MODIS OCEAN Team and the university of Miami Rosenstiel School of Marine and Atmospheric Science Remote Sensing Group.
May-June 2002
Volume 56, Number 3

Peer-reviewed research and review articles

Global climate change will affect: air, water in California
by Bryan C. Weare
| Full text HTML  | PDF  
The scientific consensus is clear that global warming is under way, but the extent of coming change is still holty debated.
As we enter the 21st century, it is possible to reach beyond the headlines to describe what is now known about climate change. The Intergovernmental Panel on Climate Change evaluated the scientific aspects of global climate change; the current consensus is described in a recent series of reports. Since the 19th century, concentrations of atmospheric carbon dioxide, methane, nitrous oxide and sulfate aerosol dust have increased significantly. While there is scientific agreement that warming is occurring, the controversy now concerns the extent of subsequent impacts in the future. In California, the impacts of global warming are likely to include reduced water availability and quality, poorer air quality, associated economic consequences, biodiversity shifts and health effects. The changes are expected to continue at an increasing pace well into the next century, perhaps outstripping our scientific, economic and social ability to cope with them.
Contract use widespread in wine grape industry
by Rachael E. Goodhue, Dale M. Heien, Hyunok Lee, Daniel A. Sumner
| Full text HTML  | PDF  
Growers with more experience, larger vineyards, more expensive wine grapes and lonager relationships with buyers were more likely to have contracts.
The use of agricultural contracts between farmers and processors or other buyers has increased substantially in recent years. Roughly half of all U.S. fruit and vegetable production is under contract. Contract usage varies widely across agricultural products. For example, 95% of poultry is raised under contract while only 13% of corn is. The wine grape industry utilizes contracts, yet little is known about the extent of contract use, or the use of specific terms and objectives. We used a survey to analyze contract use among wine grape producers, determine which users are utilizing contracts, and identify how they differ from nonusers. Ninety percent of the growers who responded to the survey have contracts, the majority of which were multiyear, averaging 3.7 years. Growers with more experience, larger vineyards, more expensive grapes and longer relationships with the buyer were more likely to enter into contracts.
Avocado thrips: New challenge for growers
by Mark S. Hoddle, Joseph G. Morse, Phil A. Phillips, Ben A. Faber, Karen M. Jetier
| Full text HTML  | PDF  
Following the 1996 arrival of avocado thrips, natural enemies and selective pesticides were identified, and other potential thrips pests and new IPM strategies were developed.
Avocado thrips arrived in California in 1996. Since then, we have made substantial progress in our understanding of this pest. We now know the area of origin of the avocado thrips and have compiled an inventory of other potential pest thrips species on avocados in Mexico and Central America. Trials have helped us to identify several selective insecticides for use in treating avocado thrips in orchards. We have also determined the relationship between thrips densities on leaves and fruit scarring, and are studying cultural and biological control practices for use in an evolving integrated pest management (IPM) program.
Graft-transmissible agent causes bark necrosis and stem pitting in plum trees
by Diana B. Marini, Adib Rowhani, Jerry K. Uyemoto
| Full text HTML  | PDF  
After two Central Valley plum orchards failed, studies were conducted to characterize the virla disease agent; numerous Prunus species were susceptible.
In two Central Valley plum orchards, nearly all the trees started exhibiting copious amounts of dark gumballs on scaffold branches and main trunks. Exposed bark showed extensive tissue necrosis and necrotic stem-pitting on the surface of the woody cylinders. Eventually, both orchards had to be removed and replanted. The symptoms were highly suggestive of a viral or viruslike disease agent. We began studies to characterize the pathogen associated with the failure of these orchards and were successful in associating the disease with a new virus that proved to have an extensive host range in many cultivated Prunus. Characterization of this virus is under way.
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California Agriculture, Vol. 56, No.3

A warmer California: Assessing the impacts of climate change
Cover:  A new sensor orbiting the Earth aboard NASA's Terra satellite is collecting the most detailed measurements ever made of the sea's surface temperature. The Moderate-resolution Imaging Spectro-radiometer (MODIS) is measuring sea surface temperature at twice the accuracy of previous satellites. Taken Jan. 1-8, 2001, this image shows cold water upwelling near the coast of Peru, and joining the South Equatorial Current, which flows westward across the Pacific Ocean. Thermal expnasion of seawater and widespread loss of land ice due to global warming have very lilely contributed to the documented rise on sea level (1 to 2 millimeters annually) during the 20th century. Image by Jesse Allen, based on data provided by the MODIS OCEAN Team and the university of Miami Rosenstiel School of Marine and Atmospheric Science Remote Sensing Group.
May-June 2002
Volume 56, Number 3

Peer-reviewed research and review articles

Global climate change will affect: air, water in California
by Bryan C. Weare
| Full text HTML  | PDF  
The scientific consensus is clear that global warming is under way, but the extent of coming change is still holty debated.
As we enter the 21st century, it is possible to reach beyond the headlines to describe what is now known about climate change. The Intergovernmental Panel on Climate Change evaluated the scientific aspects of global climate change; the current consensus is described in a recent series of reports. Since the 19th century, concentrations of atmospheric carbon dioxide, methane, nitrous oxide and sulfate aerosol dust have increased significantly. While there is scientific agreement that warming is occurring, the controversy now concerns the extent of subsequent impacts in the future. In California, the impacts of global warming are likely to include reduced water availability and quality, poorer air quality, associated economic consequences, biodiversity shifts and health effects. The changes are expected to continue at an increasing pace well into the next century, perhaps outstripping our scientific, economic and social ability to cope with them.
Contract use widespread in wine grape industry
by Rachael E. Goodhue, Dale M. Heien, Hyunok Lee, Daniel A. Sumner
| Full text HTML  | PDF  
Growers with more experience, larger vineyards, more expensive wine grapes and lonager relationships with buyers were more likely to have contracts.
The use of agricultural contracts between farmers and processors or other buyers has increased substantially in recent years. Roughly half of all U.S. fruit and vegetable production is under contract. Contract usage varies widely across agricultural products. For example, 95% of poultry is raised under contract while only 13% of corn is. The wine grape industry utilizes contracts, yet little is known about the extent of contract use, or the use of specific terms and objectives. We used a survey to analyze contract use among wine grape producers, determine which users are utilizing contracts, and identify how they differ from nonusers. Ninety percent of the growers who responded to the survey have contracts, the majority of which were multiyear, averaging 3.7 years. Growers with more experience, larger vineyards, more expensive grapes and longer relationships with the buyer were more likely to enter into contracts.
Avocado thrips: New challenge for growers
by Mark S. Hoddle, Joseph G. Morse, Phil A. Phillips, Ben A. Faber, Karen M. Jetier
| Full text HTML  | PDF  
Following the 1996 arrival of avocado thrips, natural enemies and selective pesticides were identified, and other potential thrips pests and new IPM strategies were developed.
Avocado thrips arrived in California in 1996. Since then, we have made substantial progress in our understanding of this pest. We now know the area of origin of the avocado thrips and have compiled an inventory of other potential pest thrips species on avocados in Mexico and Central America. Trials have helped us to identify several selective insecticides for use in treating avocado thrips in orchards. We have also determined the relationship between thrips densities on leaves and fruit scarring, and are studying cultural and biological control practices for use in an evolving integrated pest management (IPM) program.
Graft-transmissible agent causes bark necrosis and stem pitting in plum trees
by Diana B. Marini, Adib Rowhani, Jerry K. Uyemoto
| Full text HTML  | PDF  
After two Central Valley plum orchards failed, studies were conducted to characterize the virla disease agent; numerous Prunus species were susceptible.
In two Central Valley plum orchards, nearly all the trees started exhibiting copious amounts of dark gumballs on scaffold branches and main trunks. Exposed bark showed extensive tissue necrosis and necrotic stem-pitting on the surface of the woody cylinders. Eventually, both orchards had to be removed and replanted. The symptoms were highly suggestive of a viral or viruslike disease agent. We began studies to characterize the pathogen associated with the failure of these orchards and were successful in associating the disease with a new virus that proved to have an extensive host range in many cultivated Prunus. Characterization of this virus is under way.

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