California Agriculture, July-August 1995
Volume 49, Number 4
If medfly were here to stay...Costs of a trade ban
peer-reviewed research articles
If medfly infestation triggered a trade ban: Embargo on California produce would cause revenue, job loss
by Jerome B. Siebert, Todd Cooper
The establishment of the medfly in California would have significant impacts, particulary on the citrus industry. This study investigates the economic impacts that might arise if Asian countries imposed an embargo on California produce. Increased costs of controlling an established medfly, whether or not an embargo were imposed, would range from $493 million to $875 million. The imposition of an embargo would result in additional revenue losses of $564 million. The state economy could lose $1.2 billion in gross state product and more than 14,000 jobs.
Excess nitrogen raises nectarine susceptibility to disease and insects
by Kent M. Daane, R. Scott Johnson, Themis J. Michailides, Carlos H. Crisosto, Jeff W. Dlott, Hugo T. Ramirez, Glenn Y. Yokota, Dave P. Morgan
This multidisciplinary study examined the effects of nitrogen fertilization on nectarine yield, fruit quality, brown rot and moth pests. Results indicate that excess nitrogen fertilization did not increase fruit yield or improve fruit quality; however, fruit on overfertilized trees were more susceptible to attack from brown rot, peach twig borer and oriental fruit moth.
Drip irrigation controls soil salinity under row crops
by Blaine R. Hanson, Warren E. Bendixen
Keeping soil salinity low in the root zone is crucial to growers of salt-sensitive crops. This study investigated patterns of soil salinity under surface and subsurface drip irrigation. High soil salinity occurred midway between drip laterals for both irrigation methods and above the drip tape for subsurface drip irrigation. Rainfall leached the salts from the zones of high salinity for both irrigation methods.
Hedgerows use more water, but increase efficiency, profit in young walnuts
by David A. Goldhamer, Robert H. Beede, G. Steven Sibbett, Roger K. Kjelgren, Rebecca C. Phene, David E. Ramos
Total water use was 18.8% greater for hedgerow plantings of walnut trees than for conventionally spaced trees during years 2 through 7 of this study. Cumulative yield-and revenue-water use efficiencies were much greater with the hedgerows through year 5, but differences narrowed there-after. The hedgerows had greater total yield, but lower crop value due to smaller nuts. Although individual nut weight was strongly correlated with nut load, the relationship between nut weight and nut density was independent of tree spacing. Total gross and net hedgerow revenues were greater.
Nutrition videotapes reach low-income WIC audiences
by Amy Block Joy, Mary Lavender Fujii
Although some research exists on the effectiveness of using videotapes to deliver nutrition education to middle-income clients in clinical settings, little has been reported on the effectiveness of this approach in public health environments. This preliminary study evaluated the success of “For Goodness Sake!”, a video series teaching nutrition education to low-income participants in the Women, Infants and Children's (WIC) program. Participants reported significant increases in their consumption of broccoli and rice 3 to 4 weeks after viewing the videos.
Electrostatic sprayers improve pesticide efficacy in greenhouses
by John Kabashima, D. Ken Giles, Michael P. Parrella
Electrostatic sprayers represent a new development in greenhouse pesticide application technology. In a 3-year study, we evaluated one of the newer candidate sprayers for efficacy in controlling green peach and melon aphids while enhancing worker safety. Electrostatic application provided aphid control that was equal or superior to conventional fullvolume spray while using 40 times less water in an equivalent area. In addition, although electrostatic application provided 3.7 times more foliar deposition than the use of conventional full-volume sprays, electrostatically deposited residues were more difficult to remove mechanically. Therefore, residues from electrostatic application are less hazardous to worker health and safety than conventional full-volume wet sprays.
Parasitoid shows potential for biocontrol of eugenia psyllid
by Donald L. Dahlsten, Donald M. Kent, David L. Rowney, William A. Copper, Terri E. Young, Richard L. Tassan
The eugenia psyllid has become a major pest of eugenia, a commonly used ornamental plant in the coastal counties of California. Attempts to control this insect with insecticides have been only partially successful. A biological control program was initiated at Disneyland in Southern California in 1991. A monitoring procedure has been developed and a eulophid parasitoid, Tamarixia n. sp., was introduced from Australia in July 1992. Initial results indicate that the parasitoid has become established and has spread widely in a short period of time. Sampling shows a correlation between numbers of psyllids and parasitoids and a post-release decrease in the number of psyllids.
editorial, news, letters & science briefs
by Kenneth R. Farrell
Medfly problem simmers