California Agriculture, May-June 1995
Volume 49, Number 3
How will disaster aid reform affect California farms?
peer-reviewed research articles
How new crop disaster policy could affect California
by Hyunok Lee, Joy Harwood, Agapi Somwaru
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
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
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
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
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
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
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
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.
editorial, news, letters & science briefs
Charting DANR's future
by Henry J. Vaux
Minimizing the hazards of dormant sprays to wildlife
Gomes named new DANR VP
March was the cruelest month