California Agriculture

In some California locations, the natural regeneration of blue oak is limited by the ability of small seedlings to survive long enough to become larger saplings. This study evaluated the growth and survival of different age classes of seedlings. We found that over a 7-year period, older blue oak seedlings had a much higher survival rate than younger seedlings. Under this study’s conditions, however, the height of younger seedlings increased while that of older seedlings decreased. These results suggest that once a seedling survives approximately a decade and becomes established, it is much more likely to remain alive compared to newly germinated seedlings. Nonetheless, its height growth rate may be extremely slow.

Blue oak, a tree native only to California, is notoriously slow-growing, and its low regeneration rate has prompted concern about the species’ future survival in some areas of the state. We studied the use of fencing (exclosures) to protect seedlings from herbivores and promote faster growth. Placing exclosures 2 and 4 feet in diameter around blue oak seedlings increased their height and canopy area when compared to a control without exclosures. The 4-foot exclosures increased growth (height and canopy area) compared to the 2-foot exclosures. It appeared that exclosures reduced damage from both wild and domestic herbivores, resulting in accelerated growth rates.

We field-tested the Coyote Lure Operative Device (CLOD), a bait delivery system for coyotes originally conceived by UC Davis researchers in the 1980s. Our objectives were to determine whether free-ranging coyotes would activate CLODs repeatedly when exposed to them over a 12-month period, and whether CLOD activations varied by season. We placed CLODs in pastures with a history of chronic sheep depredation at the UC Hopland Research and Extension Center in Mendocino County. Free-ranging coyotes activated the CLODs repeatedly, but more CLODs were activated during the winter months than at other times of the year. Our study suggests that the CLOD has the potential to become an important tool for managing coyote predation on livestock when used to deliver contraceptive or predacide baits.

In 2000, the UC Statewide Integrated Pest Management Program (UC IPM) conducted a comprehensive survey of pest management decision-making and pest control practices of cotton growers in the 11 major cotton-?producing counties of California. The results indicate progress in growers’ knowledge and implementation of IPM principles and techniques, although the use of certain aspects, such as treatment thresholds for insects, often fell short of researchers’ recommendations. The survey also confirmed the central role of pest control advisers (PCAs) in IPM decision-making. Although independent PCAs communicate more with growers than do PCAs who are affiliated with product suppliers, PCA affiliation did not affect most on-the-ground pest treatment actions measured by this survey. The results indicate a need to expand IPM adoption surveys to include PCAs and to develop more effective ways of measuring IPM decision-making beyond counting the techniques used or not used.

The growth and productivity of peach fruit can be limited by many factors, including weather. Previous research indicated that early-spring temperatures for 30 days after bloom have a strong effect on early peach fruit growth, and both the time and potential fruit size at harvest. We analyzed fruit-size trends of three major cultivars in the California fresh-market peach industry (Flavorcrest, Elegant Lady and O’Henry) over a 20-year period to determine if there is a clear relationship between early-spring temperatures and packed fruit sizes industrywide. This research confirmed two significant trends: the size of packed fruit has increased over the 20-year period between 1985 and 2004, and high early-spring temperatures tended to decrease the size of packed fruit at harvest for any given year.

Subjective quality-evaluation errors in agriculture, such as discarding good-quality product and packing poor-quality product, can be costly to growers and workers. This study of workers and supervisors in a strawberry-plant packingshed revealed the danger in assuming that those responsible for quality control truly understand what is required. We found that the ability of workers to correctly count plants, and to retain or reject them (and explain why), varied considerably. The results highlight the need for employers to carefully define quality parameters, and then test employees and applicants. When top management does not agree on exactly what constitutes acceptable quality, it is difficult to expect quality-control inspectors and workers to understand. Testing, as a tool, can help growers and producers make better employee selection and placement decisions and can also be used for periodic training.

Our research group reviewed, updated and field-tested “Nutrition Competencies for California’s Children, Pre-Kindergarten through Grade 12,” a document that provides comprehensive and sequential nutrition goals for students. The review process included: (1) comparative analysis with state and national nutrition and health documents; (2) professional input by UC nutrition and education faculty and California Department of Education nutrition staff; (3) review by national, state and local experts in nutrition, education and food service; and (4) field review by and a survey of California public school teachers. The teachers that we surveyed overwhelmingly agreed that the final Nutrition Competencies document was age- and academically appropriate for students in their grade levels. More than 81% found the Nutrition Competencies document well-structured and user-friendly. The teachers supported its inclusion in the school curriculum, and requested additional support materials such as lesson plans in order to incorporate nutrition lessons into the core subject areas.