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Open Access Publications from the University of California


California Agriculture is a quarterly peer-reviewed journal reporting research, reviews and news on California’s agricultural, natural and human resources.

Volume 61, Issue 2, 2007

Issue cover


Pharmaceutical crops have a mixed outlook in California

Crops are being genetically engineered to produce a wide variety of drugs, vaccines and other pharmaceutical proteins. Although these crops may open the door to less expensive and more-readily available drugs, there is concern regarding the potential for contamination of human food and livestock feed, as well as environmental harm. The outlook for the production of pharmaceutical crops in California currently appears mixed. To date, 18 federal permits for field trials involving pharmaceutical or industrial proteins have been approved in California. However, the state’s farming community and general public have thus far rejected pharmaceutical crop production, and a handful of local governments have recently banned the cultivation of genetically modified crops, including pharmaceutical crops. In light of the many pros and cons, three major approaches — the precautionary approach, risk analysis and cost-benefit analysis — could be used to move the debate about pharmaceutical crops forward.

Growth stage influences level of resistance in glyphosate-resistant horseweed

While glyphosate-resistant horseweed has not previously been reported in California, we suspected that it might exist, especially in noncrop areas. We collected horseweed seeds from two locations in the San Joaquin Valley and treated greenhouse-grown plants at different stages with different amounts of glyphosate. This study showed that a glyphosate-resistant biotype of horseweed exists in the noncrop areas of Dinuba, in Tulare County, and that the level of resistance may be influenced by the plant’s growth stage at the time of glyphosate application.

IPM program successful in California greenhouse cut roses

We developed and tested an integrated pest management (IPM) program for the key pests of cut roses, which was based on fixed precision sampling plans, thresholds, biological control, directed sprays of reduced-risk pesticides, and cultural control. This program represented the largest effort to date to implement an IPM program in U.S. floriculture. The biological control of mites was successful at all locations, and pesticide use was generally lower in the IPM greenhouses. Future work will concentrate on reducing scouting time, improving natural-enemy release methods, and developing IPM techniques for secondary pests and powdery mildew.

Native roadside perennial grasses persist a decade after planting in the Sacramento Valley

Restoring native grassland along roadsides can provide a relatively low-maintenance, drought-tolerant and stable perennial vegetative cover with reduced weed growth, as opposed to the high-maintenance invasive annual cover (requiring intensive mowing and herbicide treatments) that dominates most Sacramento Valley roadsides. A survey of long-established roadside native-grass plantings in Yolo County showed that once established and protected from disturbance, such plantings can persist with minimal maintenance for more than a decade, retaining a high proportion of native species. The survey also showed that each species of native perennial grass displays a microhabitat preference for particular roadside topographic positions, and that native perennial grass cover is negatively affected by disturbance.

Low-income women in California may be at risk of inadequate folate intake

Folate plays a major role in preventing neural tube defects in the developing fetus, as well as in reducing the risks of cardiovascular disease, certain types of cancer and some mental health problems. We assessed the folate intakes of socioeconomically disadvantaged women of childbearing age participating in California’s Food Stamp Nutrition Education program. Of 195 women studied, 59% failed to meet the Institute of Medicine’s folate intake recommendations for women capable of becoming pregnant. We found significant differences among the ethnic groups studied: 45% of Hispanic, 65% of white and 77% of black women did not meet the recommendation for synthetic folic acid intake. This study supports the need for developing targeted nutrition-education lessons focusing on the importance of adequate folate consumption.

Mineral balances, including in drinking water, estimated for Merced County dairy herds

Dairy producers must increasingly comply with environmental regulations at the federal, state and local levels. A key to many of the regulations is the development of manure management plans to protect air, water and soil quality. Information on complete nutrient balances and excretion is necessary to control or minimize the loss of nutrients to the environment. Data from 51 randomly selected dairy farms in Merced County, in California’s Central Valley, was used to evaluate the impact of minerals in drinking water on nutrient balances and to characterize the mineral composition of manure from lactating dairy cows. We found that a lactating dairy cow producing approximately 66 pounds of milk daily might excrete 750 ± 117 grams of minerals daily, while the proportion of these minerals attributed to water ranged from 0.3% to 20%. On some dairies, controlling these minerals could reduce manure production and subsequent land applications.