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California Agriculture, Vol. 49, No.3

How will disaster aid reform affect California farms?
Cover:  Toppled almond trees were a common sight in the Central Valley after March storms wreaked their havoc. Almonds were just one of many commodities damaged by the wind, rain and cold. Almond trees had more leaves out in March than other trees. The leaf canopy acted like a sail, catching the 40 to 60 mile an hour winds and rocking the trees in saturated soils until their shallow roots pulled loose. Photo by Jack Kelly Clark
May-June 1995
Volume 49, Number 3

Peer-reviewed research and review articles

How new crop disaster policy could affect California
by Hyunok Lee, Joy Harwood, Agapi Somwaru
| Full text HTML  | PDF  
A recent study shows that with crop insurance reform, disaster aid to California's non-insurable crop producers is likely to be reduced.
With recent crop insurance reform, the federal government's responses to weather-related crop losses will change significantly. Among many changes, a newly created Non-insured Assistance Program (NAP) has important implications for California agriculture. NAP is a standing disasteraid program for non-insurable crops, including most vegetables, fruits and some tree crops. Our analysis shows that under one possible specification of NAP, crop disaster aid is likely to be sharply reduced.
Can retailers depress lettuce prices at farm level?
by Richard J. Sexton, Mingxia Zhang
| Full text HTML  | PDF  
Retailers can depress farm prices for iceberg lettuce, especially when available supplies are high and growers' bargaining power is consequently low.
In recent years, lettuce growers have expressed increasing concern that the price consumers pay for lettuce in the grocery store does not reflect the price growers receive for their crop. They contend that the bargaining power of major grocery store chains has led to retail prices that remain persistently high even when farm prices are low. This analysis examined factors that determine the difference between retail and wholesale prices for iceberg lettuce and the price farmers received in four major US. cities: Atlanta, Chicago, Los Angeles and New York. The results suggest that retailer power can indeed depress farm prices, especially when available supplies are high and growers' bargaining power is consequently low.
New equations estimate evapotranspiration in Delta
by M. N. Orang, Mark E. Grismer, Hossein Ashktorab
| Full text HTML  | PDF  
Using long-term weather data, researchers have developed equations for estimating monthly evapotranspiration. This information can be helpful in water resources planning and development.
The San Joaquin-Sacramento river delta plays a critical role in California water issues, but little information about potential evapotranspiration (ET) in the region is available for water resources planning and development. Simple equations, based on long-term weather data from Stockton and Lodi, have been developed for estimating monthly ET in the Delta. These equations can provide ET data until reliable weather stations are installed.
Stylet oil provides limited control of aphid-transmitted viruses in melons
by Kodira C. Umesh, Jesus Valencia, Chase Hurley, W. Douglas Gubler, Bryce W. Falk
| Full text HTML  | PDF  
Stylet oil reduced the incidence and spread of aphid-transmitted viruses when inoculum pressure was low.
Aphid-borne viruses pose a significant threat to California melon growers. Insecticides can kill aphids, but do not prevent the rapid virus transmission. In seven field trials conducted in Davis and the Central Valley, we studied the efficacy of JMS Stylet Oil in reducing the spread and incidence of aphid-transmitted viruses. Stylet oil reduced the incidence and spread of aphid-transmitted viruses when inoculum pressure was low. However, when inoculum pressure was high, the oil did not reduce virus spread to tolerable levels, but delayed initial infection to some degree.
Efforts to reduce stratospheric ozone loss affect agriculture
by Bryan C. Weare
| Full text HTML  | PDF  
The Montreal Protocol, an international agreement to phase out production of stratospheric ozone-depleting chemicals, Will have a Profound impact on agriculture.
Research has shown that the increased ultraviolet radiation reaching the Earth's surface resulting from stratospheric ozone loss poses a danger to everyone. Concern about ozone loss prompted many nations to ratify the Montreal Protocol, the most comprehensive international environmental agreement ever enacted. Several provisions of this protocol will have substantial, long-term effects on the agricultural industry. Agriculture contributes substantially to ozone depletion, primarily through its use of chlorofluorocarbons (CFCs) for refrigeration in processing, storage and transport of meats and produce. This paper is meant to serve as an overview of the scientific basis for ozone depletion concerns, a description of the current international policy agreement, and the possible consequences of that policy for agriculture.
Leafhopper prefers vines with greater amounts of irrigation
by Kent M. Daane, Larry E. Williams, Glenn Y. Yokota, Shawn A. Steffan
| Full text HTML  | PDF  
Field studies showed that increases in the amount of water applied correlated to increases in leafhopper nymph density and size.
To determine how irrigation influences variegated grape leaf-hopper biology and pest status, field studies were conducted in an experimental vineyard at the Kearney Agricultural Center. Results showed that increases in the amount of applied water were correlated to increases in leafhopper nymph density and size. Similarly, adult leafhoppers dispersed in greater numbers and had a higher reproductive potential on vigorously growing vines.
Postemergence herbicide controls johnsongrass, other weeds in field corn
by Jack P. Orr, Larry Mitich, Ernie Roncoroni
| Full text HTML  | PDF  
Early applications of nicosulfuron controlled johnsongrass and resulted in higher corn yields.
The new postemergence herbicide nicosulfuron (Accent) makes integrated management of johnsongrass, Sorghum halepense (L.), in field corn economically feasible and environmentally sound. In a study of its effect on johnsongrass and field corn in Yolo and Sacramento counties, nicosulfuron provided control of johnsongrass at all growth stages. However, early treatments resulted in the highest corn yields.
Improved mite sampling may reduce acaricide use in roses
by John F. Karlik, Peter B. Goodell, Gary W. Osteen
| Full text HTML  | PDF  
High-quality rose plants were produced with fewer acaricide treatments by using a rapid sampling method and treatment thresholds for spider mites.
Spider mites are considered to be the most important invertebrate pests of commercial field-grown rose plants, but sampling methods and treatment thresholds have been subjective. This study shows that roses exhibit a higher tolerance for spider mites than previously thought. Quality rose plants were produced with fewer acaricide treatmentsby using a rapid presence/absence field sampling method and treatment thresholds for spider mites.
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California Agriculture, Vol. 49, No.3

How will disaster aid reform affect California farms?
Cover:  Toppled almond trees were a common sight in the Central Valley after March storms wreaked their havoc. Almonds were just one of many commodities damaged by the wind, rain and cold. Almond trees had more leaves out in March than other trees. The leaf canopy acted like a sail, catching the 40 to 60 mile an hour winds and rocking the trees in saturated soils until their shallow roots pulled loose. Photo by Jack Kelly Clark
May-June 1995
Volume 49, Number 3

Peer-reviewed research and review articles

How new crop disaster policy could affect California
by Hyunok Lee, Joy Harwood, Agapi Somwaru
| Full text HTML  | PDF  
A recent study shows that with crop insurance reform, disaster aid to California's non-insurable crop producers is likely to be reduced.
With recent crop insurance reform, the federal government's responses to weather-related crop losses will change significantly. Among many changes, a newly created Non-insured Assistance Program (NAP) has important implications for California agriculture. NAP is a standing disasteraid program for non-insurable crops, including most vegetables, fruits and some tree crops. Our analysis shows that under one possible specification of NAP, crop disaster aid is likely to be sharply reduced.
Can retailers depress lettuce prices at farm level?
by Richard J. Sexton, Mingxia Zhang
| Full text HTML  | PDF  
Retailers can depress farm prices for iceberg lettuce, especially when available supplies are high and growers' bargaining power is consequently low.
In recent years, lettuce growers have expressed increasing concern that the price consumers pay for lettuce in the grocery store does not reflect the price growers receive for their crop. They contend that the bargaining power of major grocery store chains has led to retail prices that remain persistently high even when farm prices are low. This analysis examined factors that determine the difference between retail and wholesale prices for iceberg lettuce and the price farmers received in four major US. cities: Atlanta, Chicago, Los Angeles and New York. The results suggest that retailer power can indeed depress farm prices, especially when available supplies are high and growers' bargaining power is consequently low.
New equations estimate evapotranspiration in Delta
by M. N. Orang, Mark E. Grismer, Hossein Ashktorab
| Full text HTML  | PDF  
Using long-term weather data, researchers have developed equations for estimating monthly evapotranspiration. This information can be helpful in water resources planning and development.
The San Joaquin-Sacramento river delta plays a critical role in California water issues, but little information about potential evapotranspiration (ET) in the region is available for water resources planning and development. Simple equations, based on long-term weather data from Stockton and Lodi, have been developed for estimating monthly ET in the Delta. These equations can provide ET data until reliable weather stations are installed.
Stylet oil provides limited control of aphid-transmitted viruses in melons
by Kodira C. Umesh, Jesus Valencia, Chase Hurley, W. Douglas Gubler, Bryce W. Falk
| Full text HTML  | PDF  
Stylet oil reduced the incidence and spread of aphid-transmitted viruses when inoculum pressure was low.
Aphid-borne viruses pose a significant threat to California melon growers. Insecticides can kill aphids, but do not prevent the rapid virus transmission. In seven field trials conducted in Davis and the Central Valley, we studied the efficacy of JMS Stylet Oil in reducing the spread and incidence of aphid-transmitted viruses. Stylet oil reduced the incidence and spread of aphid-transmitted viruses when inoculum pressure was low. However, when inoculum pressure was high, the oil did not reduce virus spread to tolerable levels, but delayed initial infection to some degree.
Efforts to reduce stratospheric ozone loss affect agriculture
by Bryan C. Weare
| Full text HTML  | PDF  
The Montreal Protocol, an international agreement to phase out production of stratospheric ozone-depleting chemicals, Will have a Profound impact on agriculture.
Research has shown that the increased ultraviolet radiation reaching the Earth's surface resulting from stratospheric ozone loss poses a danger to everyone. Concern about ozone loss prompted many nations to ratify the Montreal Protocol, the most comprehensive international environmental agreement ever enacted. Several provisions of this protocol will have substantial, long-term effects on the agricultural industry. Agriculture contributes substantially to ozone depletion, primarily through its use of chlorofluorocarbons (CFCs) for refrigeration in processing, storage and transport of meats and produce. This paper is meant to serve as an overview of the scientific basis for ozone depletion concerns, a description of the current international policy agreement, and the possible consequences of that policy for agriculture.
Leafhopper prefers vines with greater amounts of irrigation
by Kent M. Daane, Larry E. Williams, Glenn Y. Yokota, Shawn A. Steffan
| Full text HTML  | PDF  
Field studies showed that increases in the amount of water applied correlated to increases in leafhopper nymph density and size.
To determine how irrigation influences variegated grape leaf-hopper biology and pest status, field studies were conducted in an experimental vineyard at the Kearney Agricultural Center. Results showed that increases in the amount of applied water were correlated to increases in leafhopper nymph density and size. Similarly, adult leafhoppers dispersed in greater numbers and had a higher reproductive potential on vigorously growing vines.
Postemergence herbicide controls johnsongrass, other weeds in field corn
by Jack P. Orr, Larry Mitich, Ernie Roncoroni
| Full text HTML  | PDF  
Early applications of nicosulfuron controlled johnsongrass and resulted in higher corn yields.
The new postemergence herbicide nicosulfuron (Accent) makes integrated management of johnsongrass, Sorghum halepense (L.), in field corn economically feasible and environmentally sound. In a study of its effect on johnsongrass and field corn in Yolo and Sacramento counties, nicosulfuron provided control of johnsongrass at all growth stages. However, early treatments resulted in the highest corn yields.
Improved mite sampling may reduce acaricide use in roses
by John F. Karlik, Peter B. Goodell, Gary W. Osteen
| Full text HTML  | PDF  
High-quality rose plants were produced with fewer acaricide treatments by using a rapid sampling method and treatment thresholds for spider mites.
Spider mites are considered to be the most important invertebrate pests of commercial field-grown rose plants, but sampling methods and treatment thresholds have been subjective. This study shows that roses exhibit a higher tolerance for spider mites than previously thought. Quality rose plants were produced with fewer acaricide treatmentsby using a rapid presence/absence field sampling method and treatment thresholds for spider mites.

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