California Department Of Food And Agriculture Research Articles

Peel Fluorescence as a Means to Identify Freeze-damaged Navel Oranges

The use of ultraviolet fluorescence to identify freeze-damaged navel oranges (Citrus sinensis) was evaluated using fruit harvested following a natural freeze that occurred in California in Jan. 2007. Navel oranges were harvested after the freeze from 14 sites that were previously determined to have a slight to moderate amount of freeze damage. The fruit were evaluated for the presence of small yellow spots characteristic of freeze damage that fluoresce when viewed under a ultraviolet-A (365 nm) source and were then cut and rated using a method currently used by the California Department of Food and Agriculture (CDFA) to determine the presence of internal freeze damage. The percentage of freeze-damaged fruit in each lot as determined by the CDFA method ranged from 0% to 89%. The accuracy of classifying fruit as freeze damaged in each lot by peel fluorescence averaged 44%, with the fruit lots containing the greatest amount of freeze damage having the highest classification percentages. False-positives occurred at a lower rate than false-negatives among the lots. Although some fading was evident, the fluorescence persisted and was readily visible for at least 9 weeks after the freeze event. Removal of fruit with ultraviolet peel fluorescence was ineffective in reducing the percentage of damaged fruit within the examined lots. In the second part of the test, eighteen lots of potentially freeze-damaged fruit were obtained from a packing house, immediately evaluated for freeze damage using ultraviolet light, and then after 4 weeks of storage, were evaluated again using the CDFA method. Fruit that had a slight to moderate degree of freeze damage were tasted and evaluated for sensory characteristics. Both methods of freeze damage detection were poorly related to the sensory characteristics.

Peel Fluorescence as a Means to Identify Freeze-damaged Navel Oranges

The use of ultraviolet fluorescence to identify freeze-damaged navel oranges (Citrus sinensis) was evaluated using fruit harvested following a natural freeze that occurred in California in Jan. 2007. Navel oranges were harvested after the freeze from 14 sites that were previously determined to have a slight to moderate amount of freeze damage. The fruit were evaluated for the presence of small yellow spots characteristic of freeze damage that fluoresce when viewed under a ultraviolet-A (365 nm) source and were then cut and rated using a method currently used by the California Department of Food and Agriculture (CDFA) to determine the presence of internal freeze damage. The percentage of freeze-damaged fruit in each lot as determined by the CDFA method ranged from 0% to 89%. The accuracy of classifying fruit as freeze damaged in each lot by peel fluorescence averaged 44%, with the fruit lots containing the greatest amount of freeze damage having the highest classification percentages. False-positives occurred at a lower rate than false-negatives among the lots. Although some fading was evident, the fluorescence persisted and was readily visible for at least 9 weeks after the freeze event. Removal of fruit with ultraviolet peel fluorescence was ineffective in reducing the percentage of damaged fruit within the examined lots. In the second part of the test, eighteen lots of potentially freeze-damaged fruit were obtained from a packing house, immediately evaluated for freeze damage using ultraviolet light, and then after 4 weeks of storage, were evaluated again using the CDFA method. Fruit that had a slight to moderate degree of freeze damage were tasted and evaluated for sensory characteristics. Both methods of freeze damage detection were poorly related to the sensory characteristics.

Measurement of transferable chemical residue from nylon carpet using the California roller and a new mega-California roller

Human chemical exposures resulting from transfer of surface deposition on indoor nylon carpets may be estimated by measuring transferable residues (μ g chemical/cm2 carpet). A weighted roller developed at California Department of Food and Agriculture (CDFA) has been extensively used to sample transferable residue for estimates of human exposure in risk characterization. A modified roller has been developed to evaluate the influence of pressure on transferable chemical residue since weight and force (or pressure, kg/m2) may vary person-to-person and activity-to-activity. A 30.5 cm diameter roller was used to apply 60 to 2100 kg/m2 to bracket pressures exerted by humans on a flat nylon-carpeted surface. Measurements of transferable cyfluthrin residues were made after 1, 7, and 21 days. Total Soxhlet extractable cyfluthrin residues were relatively constant during the test period. Residue transferability decreased during the study period. Modest increases in the transferability of surface residues were observed over the broad range of pressures applied by the modified roller.

Health Hazard Assessment for Native Americans Exposed to the Herbicide Fluridone via the Ingestion of Tules at Clear Lake, California, USA

ABSTRACT This study addresses concerns expressed by Native Americans regarding exposure via the consumption of aquatic vegetation to the herbicide fluridone (active ingredient) used by the California Department of Food and Agriculture (CDFA) Hydrilla Eradication Program in Clear Lake, California. In 2005, the Department monitored lakeshore vegetation, water, and sediment at four locations, before and after seasonal applications of fluridone. Subchronic and chronic exposures were evaluated, and hazard quotients calculated for a worst-case exposure (WCE) scenario. Ingestion rates and other exposure factors were developed in public meetings with tribal members. Environmental sampling found fluridone present at extremely low levels in tule vegetation, water, and sediment. Exposures were four times greater in subchronic timeframes than chronic timeframes; however, hazards were less due to the 25-fold larger reference dose (RfD) used for subchronic calculations: RfD(subchronic) = 2.0 mg/kg-day, RfD(chronic) = 0.08 mg/kg-day. Conservative, child, total daily ingestion (TDI) doses were calculated to be 8.3 × 10−5 mg/kg-day (subchronic) and 2.1 × 10−5 mg/kg-day (chronic). Hazard quotients (HQ) for subchronic and chronic exposures were on the order of 10−5 and 10−4, respectively, indicating that at current application regimes, there is little to no hazard of adverse effects from fluridone exposure via ingesting Clear Lake tules.

Characterizing the solid–solution partitioning coefficient and plant uptake factor of As, Cd, and Pb in California croplands

In risk assessment models, solid–solution partition coefficient, K d, and plant uptake factor, PUF, are often employed to depict the fate and transport of trace elements in soils. The trustworthiness of risk assessments depends on the reliability of the parameters used. In this study, we examined K d and PUF for As, Cd and Pb based on soils and plant tissues obtained from 70 crop production fields in California. We also examined the California portion of a nationwide survey of trace elements in cropland soils conducted by the Soil Survey, Natural Resources Conservation Service, USDA. Results showed that the K d and PUF for cropland soils are probabilistic in nature and follow log-normal distributions. The trace element concentration of the soil solution did not appear to be a more appropriate estimator of PUF than the total soil element content. The K d used in the CDFA (California Department of Food and Agriculture) study had a much wider range than that could occur in California croplands while the PUF used in the CDFA risk assessment was comparable to patterns observed in the field measurements.

High Temperature Solarization for Production of Weed-free Container Soils and Potting Mixes

A double-tent solarization technique, which accumulates higher soil temperatures than solarization of open fields, was recently approved by the California Department of Food and Agriculture (CDFA) as a nematicidal treatment for container nurseries. Due to the need for broad-spectrum pest control in container nursery settings, this technique was tested to determine its usefulness as an herbicidal treatment. Laboratory-derived thermal death dosages (temperatur × time) for several weed species important in California, including common purslane (Portulaca oleracea), tumble pigweed (Amaranthus albus), and black nightshade (Solanum nigrum), were previously determined and the data were used as guidelines for devising treatment duration in this study. In two field experiments conducted in 1999 and 2000 to validate the laboratory data, moist soil was placed in black polyethylene planting bags [3.8 L (1 gal) volume], artificially infested with seeds of the three test species, and subjected to 0 to 24 hours of double-tent solarization after reaching a threshold temperature of 60 °C (140 °F) (about 1.5 to 2.0 h after initiation of the experiment). In 1999, samples were removed at 2, 4, 20, and 24 hours after reaching the 60 °C threshold, then incubated to ameliorate possible secondary dormancy effects. Seeds failed to germinate in any of the solarized treatments. In 2000, samples were removed at 0, 1, 2, and 6 h after reaching 60 °C. Again, apart from the nonsolarized control treatment, all weed seeds failed to germinate at any of the sampling periods, in accordance with prior laboratory thermal death results. Reference tests to estimate effects of container size on soil heating showed that soil in smaller container sizes (soil volume) reached higher temperatures, and were maintained at high temperature [above 60 °C (140 °F)] for a longer period of time, than larger container sizes. The double-tent solarization technique can be used by commercial growers and household gardeners to effectively and inexpensively produce weed-free soil and potting mixes in warmer climatic areas.

Biomonitoring and whole body cotton dosimetry to estimate potential human dermal exposure to semivolatile chemicals

Current methods of estimating absorbed dosage (AD) of chemicals were evaluated to determine residue transfer from a carpet treated with chlorpyrifos (CP) to humans who performed a structured exercise routine. To determine the dislodgeability of residue, a California Department of Food and Agriculture (CDFA) roller was applied to a flat cotton cloth upon a treated carpet. Levels ranged from 0.06 to 0.99 microg CP/cm2. Cotton whole body dosimeters (WBD) were also used to assess residue transfer. The dosimeters retained 1.5 to 38 mg CP/person. Urine biomonitoring (3 days) for 3,5,6-trichloro-2-pyridinol (TCP) of persons who wore only swimsuits revealed a mean AD of 176 microg CP equivalents/person. The results show that the AD depends on the extent of contact transfer and dermal absorption of the residue. Default exposure assessments based upon environmental levels of chemicals and hypothetical transport pathways predict excessive exposure. The cotton WBD retains chemical residues and may be effectively used to predict dermal dose under experimental conditions.

U.S. EPA reregistration eligibility decision (RED) for the rodenticide cluster: overview of the regulatory process, response of registrants and stakeholders, and implications for agricultural and urban rodent control

Author(s): Silberhorn, Eric M.; Hobson, James F.; Miller, Gerald H.; Condos, Nicholas J. | Abstract: After several years of reviewing study data and conducting risk assessments, in September of 1998 the U.S. Environmental Protection Agency (U.S. EPA) issued for comment a Reregistration Eligibility Decision (RED) document for pesticide products in the Rodenticide Cluster. The RED document covered 243 rodenticide products containing the following active ingredients: brodifacoum, bromadiolone, bromethalin, chlorophacinone, diphacinone and its sodium salt, and pival and its sodium salt. The U.S. EPA’s human health risk assessment in the RED document concluded that it was concerned about the risk to children due to accidental exposures to these chemicals through use in and around residences. With regard to ecological effects, the Agency concluded that there is a high risk of secondary poisoning, especially to mammals, from the use of these rodenticides outdoors in rural and suburban areas. In order to address the potential risks to children, the U.S. EPA initially required several mitigation measures designed to minimize exposure (e.g., addition of dye and bittering agent to formulations, labeling changes). The Agency also initiated implementation of a Rodenticide Stakeholder Process through which these and other risk mitigation measures would be discussed and required as needed. To help mitigate potential risks to non-target wildlife, the Agency initially determined that all uses of field-bait rodenticides containing more than 0.005% of chlorophacinone or diphacinone were ineligible for reregistration. The U.S. EPA also decided that all rodenticide products labeled for field use (except those limited to manual underground baiting) should be reclassified as Restricted Use pesticides. This paper reviews the regulatory process for the Rodenticide Cluster RED and discusses the response of the California Department of Food and Agriculture (CDFA) and other registrants to the requirements proposed in the RED document including formation of the Rodenticide Registrants Task Force (RRTF). It also outlines how an on-going dialogue with the Agency, both through the Rodenticide Stakeholder Process and in separate discussions, has diminished the RED requirements from those originally proposed. In addition, the paper discusses the implications and potential impacts of the current RED reregistration requirements for those applicators involved in agricultural and urban rodent control.

Chlorophacinone and diphacinone: standard Mus musculus and Peromyscus maniculatus anticoagulant laboratory tests

Author(s): McCann, Geraldine R. | Abstract: The Vertebrate Pest Control Research Advisory Committee, through a cooperative agreement with the California Department of Food and Agriculture (CDFA), funded laboratory studies at the National Wildlife Research Center (NWRC). The objective of the studies was to obtain efficacy data for controlling house mice (Mus musculus) and deer mice (Peromyscus maniculatus) that would provide partial fulfillment of the requirements established by the Environmental Protection Agency (EPA) for the re-registration of the CDFA’s 0.01% chlorophacinone and 0.01% diphacinone grain bait labels. Swiss-Webster mice and deer mice from an on site breeding colony were placed on 15- day, two-choice feeding and efficacy trials. The control treatment groups received two dishes each containing the Office of Pesticide Programs (OPP) designated standard rat and mouse challenge diet. The treated groups received one dish of the standard OPP rat and mouse challenge diet and a second dish of the treated grain baits: 0.01% chlorophacinone (two groups of 20 animals, Groups II and III ), or 0.01% diphacinone (two groups of 20 animals, Groups II and III ) grain bait. Results from the treated groups of the four tests are reported. House mice on 0.01% chlorophacinone: female mortality was 100% in Group II and 90% in Group III. Total dietary consumption of treated bait was 23.0% of the total bait consumption. House mice on 0.01% diphacinone: female mortality was 90% in Group II and 100% in Group III. Total dietary consumption of treated bait was 18.2% of the total bait consumption. Deer mice on 0.01% chlorophacinone: female mortality in Groups II and III was 100%. Total dietary consumption of treated bait was 63.1% of the total bait consumption. Deer mice on 0.01% diphacinone: female mortality in Groups II and III was 100%. Total dietary consumption of treated bait was 66.3% of the total bait consumption. In conclusion, the female house mice ate less than the male house mice with the same mortality rate (between 90% and 100%); while the female Peromyscus ate more than the male Peromyscus, they had the same mortality rate (100%). The anticoagulant grain bait test mortality results for both house mice and deer mice met the suggested performance standard for the EPA Pesticide Assessment Guidelines.

Risk factors for systemic illnesses following agricultural exposures to restricted organophosphates in California, 1984-1988.

Organophosphate (OP)-related systemic illnesses reported to the Worker Health and Safety (WH&S) Branch, and restricted OP-related agricultural use data reported to the Information Services Branch at the California Department of Food and Agriculture (CDFA) (now CAL-EPA) during 1984-1988 were used to assess factors associated with OP-related systemic illnesses. Counts of OP-related systemic illnesses (numerator), relative to OP-related use data (denominator), such as pounds applied, number of applications, and acres treated (pounds applied/acres treated), were analyzed by crop treated, season of application, method of application, geographic region, and by specific OP applied. A Relative Illness/Use Ratio (RIUR) was calculated by Poisson regression. The highest risk of systemic illness was associated with OP applications to fleshy fruit (mainly fruit trees) compared to all other crops combined (RIUR = 2.9, 95%CI = 2.2-3.9) using pounds applied in the denominator, followed by vegetables and melons (RIUR = 1.9, 95%CI = 1.4-2.4). Air applications resulted in higher RIURs for systemic illness than did ground applications (RIUR = 2.1, 95%CI = 1.7-2.5). Specific OPs that showed significantly elevated RIURs for systemic illness when compared to other OPs were Mevinphos (RIUR = 5.8, 95%CI = 5.0-6.8), Demeton (RIUR = 4.3, 95%CI = 2.6-7.1), Oxydemeton-Methyl (RIUR = 3.8, 95%CI = 3.0-4.9), Methamidophos (RIUR = 1.6, 95%CI = 1.2-2.0) and Azinphos-Methyl (RIUR = 1.3, 95% CI = 1.1-1.6).

Preventing Nitrate Groundwater Contamination in California: A Nonregulatory Approach

Nitrate contamination of groundwater is a widespread problem in California, potentially causing human health problems and contributing to high costs of well remediation. The Fertilizer Research and Education Program (FREP) of the California Department of Food and Agriculture (CDFA) was created in 1990 to advance the environmentally safe and agronomically sound use of fertilizing materials. Since 1991, 51 research and education projects have been funded. Priority cropping systems include fruit and nut orchards on the east side of the San Joaquin Valley and cool season vegetables in the coastal regions of central California. Promising results from these projects are (i) the development of quick diagnostic tools that allow growers to closely monitor crop nutritional status, and (ii) provision of soil and crop fertility knowledge to growers and consultants through a wide variety of educational programs. California's multitude of crops and climates pose a big challenge. With over 200 crops grown in California, it is impossible to develop adaptive research and outreach projects to effectively address every situation. Therefore, FREP's approach has been to concentrate on those farming systems that pose the highest potential threat and where payoffs appear most promising.

Irrigation practices, herbicide use and ground-water contamination in citrus production: a case study in California

The citrus industry in Tulare County, CA is a major user of herbicides. The California Department of Food and Agriculture (CDFA) conducted a mailing survey of citrus growers in Tulare County in 1988 to identify and characterize irrigation and herbicide practices that might be associated with reported well-water contamination by three herbicides commonly used in citrus production. These herbicides, in decreasing frequency of presence in well water, were simazine, diuron and bromacil. The response rate to the questionnaire was 41%. Simazine was rated as the most important herbicide used in citrus production. However, the response to the survey suggests a broad range of chemical weed-control practices. Results indicate that production of citrus plays a role in herbicide well water contamination.