California Agriculture, March-April 1990
Volume 44, Number 2
peer-reviewed research articles
Sierra Foothill Range Field StationThirty years of research: an overview
by Charles A. Raguse, Gary A. Beall, John L. Hull, Douglas McCreary, Charles B. Wilson
The Sierra station, near Browns Valley in northern California, will be 30 years old this June:As can be seen from the air, the station's terrain is typical of much of California's foothill rangelands. Wooded, partially wooded, and cleared hills surround the headquarters and slope down to the Timbuctoo Bend of the Yuba River. The following eight reports indicate the variety of subjects covered by the research program at this center. (Cover photo by Charles Raguse)
Update on short-duration grazing study on irrigated pasture
by Kenneth L. Taggard, Charles A. Raguse, Melvin R. George, John L. Hull, Cynthia Daley, J. M. Connor
Two-year results showed similar responses to two levels of pasture accumulation-grazing utilization management. Orchardgrass height and capacitance probe readings were both useful in monitoring forage availability, but stocking rate predictions using grass height were less variable and change in grass height during grazing was more closely related to seasonal liveweight gain.
Managing bovine pinkeye in beef calves
by Lisle W. George
Two field studies showed that a widespread pinkeye epidemic in a herd can be effectively treated with injections of long-acting oxytetracycline, followed by feeding the antibiotic in the ration. When the disease is less prevalent, injecting affected animals with penicillin or oxytetracycline is effective.
Supplements evaluated for wintering range calves
by John R. Dunbar, Cindy A. Daley, J. M. Connor, Charles B. Wilson, Charles A. Raguse, Thomas R. Famula, Melvin R. George
In two range feeding trials to evaluate supplemental nitrogen and/or bypass protein source and stocking densities, calves at a low density gained more weight than high-density groups. Dollar return during the supplementation phase, however, was highest from high-density groups fed a combination of urea and corn gluten meal.
Blue oaks withstand drought
by Douglas D. McCreary
Many blue oaks in California lost their leaves early in 1987 and 1988 after prolonged periods of low rainfall. A study found that summer defoliation had little short-term effect on growth or survival, suggesting that blue oaks are well adapted to withstand periodic droughts.
Selective oak removal does not harm water quality
by Michael J. Singer, Xiaohong Huang, Charlette Epifanio
Measurements before and after removal of oaks from 14% of a 250-acre watershed indicated small but not statistically significant increases in the runoff/rainfall ratio and no change in nutrient or sediment removal. Careful, selective oak removal appeared to have no harmful effect on water quality.
Wildlife diversity of the central Sierra foothills
by William M. Block, Michael L. Morrison
A 3-year study of wildlife-habitat relationships in the oak woodlands of California's Sierra foothills found a wide range of species. This was directly related to the diversity of habitats provided by oak woodlands.
Seasonal activity of two human-biting ticks
by Robert S. Lane
In northern California, the western black-legged tick is considered the primary vector of the spirochete that causes Lyme disease. That tick and the Pacific Coast tick also can be carriers of several other diseases. In one study to learn when humans and other animals are at greatest risk of exposure, adults of both tick species were found to be most abundant during the cooler seasons.
Eucalyptus shows unexpected cold tolerance
by Janine K. Hasey, J. M. Connor
Although some species of eucalyptus trees in an experimental plantation were damaged in a 1989 cold snap, several species and clones survived temperatures lower than previously thought to be tolerated. The trees are in a low-elevation Sierra foothill test planting used for studies assessing fuelwood growth rates.
Use of long-range weather forecasts in crop predictions
by Bryan G. Weare
Uncertainties in weather forecasts still present the greatest problem in making useful crop predictions. Weather variables needed for crop growth models are minimum and maximum temperatures, precipitation, and solar radiation. Each of the three potential sources of long-range forecasts of such variables has deficiencies, but improvements offer some encouragement.
Grafting California native oaks
by William D. Tietje, John H. Foott, Elizabeth L. Labor
Preliminary results of grafting blue oak and valley oak scions to blue oak rootstock are encouraging. It appears that grafting of California native oaks has potential research and management applications.
Control of two avocado mite pests
by J. Blair Bailey, Kirk N. Olsen
Several materials were tested for possible use when avocado brown mite and sixspotted mite populations build up, threatening to cause extensive leaf drop. Sulfur was effective against avocado brown mite. Others, at present unregistered for this use, were effective against both mites.
editorial, news, letters & science briefs
Research and extension centers: vital link in the flow of knowledge
by Kenneth R. Farrell