California Agriculture April-June 2007 News Release

FOR IMMEDIATE RELEASE: 2007
CONTACT: Janet Byron, 510-987-0668 or janet.byron@ucop.edu

Native perennial grasses were thriving for a decade or more after planting along Sacramento Valley roadsides and required little maintenance, scientists report in a peer-reviewed study published in the April-June 2007 issue of the University of California’s California Agriculture journal.

“Native grasses are somewhat labor-intensive to establish on roadsides, but after a few years they offer a low-maintenance alternative to the nonnative, invasive plants that dominate many California roadways, which must be treated with frequent mowing and herbicide sprays,” says Ryan O’Dell, restoration ecologist at UC Davis and the study’s lead author.

O’Dell and colleagues Steve Young and Vic Claassen, all with the UC Davis Department of Land, Air, and Water, studied nine native-grass plots established by the Yolo County Resource Conservation District in 1993.

After they became established, the native grasses successfully out-competed invasive, nonnative species such as Italian ryegrass and yellow starthistle. In general, many native perennial grasses can remain green well into California’s dry season, reduce fire hazards, and provide high-quality forage and habitat for native animals, O’Dell says. “The cost of installing native grassland can vary from about $500 to $1,400 per acre, and maintenance costs range from about $50 to $150 per acre for the next several years. But long-term, native perennial grasses are cost-effective and often require little maintenance.”

The authors found that certain native perennial grasses prefer particular microhabitats in the roadside environment. For example, purple needlegrass and blue wildrye are more drought-tolerant and established themselves on shoulders and backslopes, while meadow barley and creeping wildrye were more suitable for wetter swales.

“If a roadside site’s local conditions are not known or are highly variable across the site, planting a mix of all four species in all topographic zones has the potential to allow each species to establish itself in its optimal microhabitat,” O’Dell says. —Back to top

Pharmaceutical crops — those genetically engineered to produce medicines, vaccines and other pharmaceutical proteins — have been cultivated on a limited scale in California amid increasing U.S. Department of Agriculture regulations to reduce risk of gene flow and contamination of human food and livestock feed, according to a review article published in the April-June 2007 issue of the University of California’s peer-reviewed California Agriculture journal. See the entire current issue of California Agriculture at http://californiaagriculture.ucop.edu.
Eighteen federal permits were issued between 1996 and March 2007 for field trials in California involving pharmaceutical or industrial proteins, according to article author Michelle Marvier, associate professor of biology at Santa Clara University. Of these, 12 were classified as Confidential Business Information, meaning that the public did not have access to information about the gene source or the specific pharmaceutical or industrial protein engineered into the crops, which included maize (corn), leaf mustard, rapeseed, rice and tobacco.

In an eight-page article, Michelle Marvier, associate professor of biology and environmental studies at Santa Clara University,Marvier explores the complex scientific, environmental and public policy issues surrounding pharmaceutical crops, and sets forth three frameworks for assessing their risks and benefits.

“Like many new technologies, the genetic engineering of crops to produce pharmaceutical products has great promise. Bananas that could cheaply and easily deliver vaccines throughout the tropics could be a wonderful invention,” Marvier wrote. “But there are downsides; it will be difficult to avoid food contamination and potential harmful effects to wildlife if pharmaceuticals are widely produced in food crops grown out of doors.”

Eighteen federal permits were issued between 1996 and March 2007 for field trials in California involving pharmaceutical or industrial proteins. Some of these approved permits were for field trials of Ventria Bioscience’s rice, engineered to express human genes with medicinal properties. These field trials were opposed by rice growers concerned about the possible contamination of rice destined for export, andVentria has since moved its production of pharmaceutical rice out of California.

Also in the current issue, University of California researchers report on the emergence of glyphosate (Roundup)–resistant horseweed in noncrop areas of California. While the authors did not determine the source of horseweed resistance in these areas, there have been numerous reports of Roundup-resistant weeds occurring near row crops such as corn and soybeans that have been genetically engineered to be resistant to the herbicide glyphosate.

These two articles continue a California Agriculture series on the risks and benefits of agricultural biotechnology, which began with peer-reviewed articles on gene flow, and transgenic animals and fish in the July-September 2006 issue: http://californiaagriculture.ucop.edu/0603JAS/toc.html. —Back to top

Folate levels low in many low-income California women

Nearly 60 percent of low-income California women of childbearing age are not consuming enough folate to meet recommended levels for preventing birth defects, according to a peer-reviewed study published in the April-June 2007 issue of the University of California’s California Agriculture journal.

Folate is a B vitamin found in foods such as liver, lentils and orange juice. In adults, folate deficiencies are associated with chronic conditions such as anemia, cardiovascular disease and certain cancers, and women deficient in folate are more likely to have babies with neural tube defects such as spina bifida or anencephaly. Since 1998, the United States has required the mandatory fortification of enriched grains — including breads and breakfast cereals — with synthetic folic acid (SFA), which is more readily available to the body than dietary folate.

Researchers with the UC Davis Department of Nutrition studied 195 low-income women (18 to 45 years old) participating in California’s Food Stamp Nutrition Education program, using a validated dietary folate screener. They found that 59 percent of the study participants were not meeting the Institute of Medicine’s recommendation of 400 micrograms SFA per day for women of childbearing age.

“Despite the national fortification program, low-income women in California may be at risk of suboptimal folate status,” says Emily Cena, the study’s lead author.

Interestingly, the researchers also found that, on average, the Hispanic women studied consumed significantly more SFA and total dietary folate than the black and white women studied. Although the data does not explain the reasons for this finding, Cena says: “The traditional Mexican diet is more likely to include folate-rich foods such as beans, fortified tortillas and fortified rice. We also found that Hispanic women were more likely to take vitamin supplements than white and black women.” Nonetheless, 45% of the Hispanic women studied had SFA intakes below the Institute of Medicine’s recommendation. —Back to top

A new integrated pest management (IPM) program for cut roses has dramatically reduced the volume of pesticides sprayed in California greenhouses and launched a successful biological control of spider mites, scientists report in a peer-reviewed study published in the April-June 2007 issue of the University of California’s California Agriculture journal.

“This program represents the first and largest effort to demonstrate and implement an IPM strategy on floriculture crops in the United States,” the authors wrote. “We have shown that high-quality roses can be produced with substantially fewer pesticides and with the incorporation of biological controls into mainstream floriculture.”

In the mid-1990s, California rose growers reached a crisis point when pesticide resistance, costs and limited pesticide availability threatened growers’ ability to effectively manage twospotted spider mites, one of the most important pest of cut roses grown in greenhouses. The study — conducted with eight commercial growers in San Diego, Santa Barbara and Santa Cruz counties — showed that a predatory mite called Phytoseiulus persimilus could effectively and economically control twospotted spider mites. The growers applied vials of P. persimilus (containing 2,000 predators each) when between 10 percent and 25 percent of randomly sampled rose leaves were infested.

To control western flower thrips, another important pest of cut roses, growers switched to commercially available, reduced-risk pesticides and targeted lower-volume sprays to just the upper canopy of the hedge (at 70 gallons per acre) — where thrips are most prevalent — rather than the full-volume wet sprays (at 275 gallons per acre) typical in conventional cut-rose greenhouses. The growers also implemented cultural controls such as removing fully open flowers, where thrips lay their eggs.

The program for cut roses was the result of a state-sponsored partnership among cut-flower growers, scientists and pesticide regulators. Since the 1970s, the University of California has been a global leader in promoting IPM, which bases agricultural pest-management decisions on economic thresholds and encourages the strategic use of biological, cultural and chemical controls in order to limit environmental impacts. —Back to top

California Agriculture is the University of California’s peer-reviewed journal
of research in agricultural, human and natural resources.
For a free subscription, click here, call (510) 987-0044 or write to calag@ucop.edu
For a printed copy of California Agriculture, media should e-mail janet.byron@ucop.edu
or call (510) 987-0668.