- Author: Pamela Kan-Rice
- Author: Jim Downing
2016 is the final year for the soil fumigant to be used in California crop fields.
For many years, California growers relied on methyl bromide to kill a wide range of soil-borne pests, from fungi to insects to weeds, before planting crops. 2016 marks the last year in which the highly effective soil fumigant will be available.
The University of California's peer-reviewed journal California Agriculture examines the impact of the methyl bromide phaseout on strawberries, California's third most valuable crop, behind only almonds and grapes, with annual farmgate sales of $2.5 billion.
First identified as an ozone-depleting compound in 1991, methyl bromide was scheduled for phaseout in the United States by 2005 under the Montreal Protocol, an international agreement to protect the stratospheric ozone layer.
While methyl bromide was used for many crops, California strawberry growers found it irreplaceable, which helped the industry win exemptions that have allowed a significant, though declining, quantity of the chemical to be used through 2016. Despite years of research into alternatives, no equally effective replacement has emerged.
Berry industry grows dramatically
In the first research article, UC Cooperative Extension advisors Laura Tourte and Mark Bolda and Karen Klonsky, emeritus UC Cooperative Extension economics specialist, review economic data on the berry sector — blackberries and raspberries as well as strawberries — in Santa Cruz and Monterey counties. They look ahead to factors, including water, consumer demands, labor, invasive pests, and the full phaseout of methyl bromide, that are likely to shape future growth.
Methyl iodide controversy
In a paper chronicling events leading up to the 2012 withdrawal of methyl iodide, once promoted as a viable methyl bromide substitute, Julie Guthman, UC Santa Cruz professor in the Department of Social Sciences, reports survey findings that point to a variety of reasons why strawberry growers did not move quickly to adopt the chemical after it was approved by state regulators. Concerns about public opposition topped the list, followed by a variety of other factors, including concern about methyl iodide's toxicity, and a lack of strong incentive to switch to the new chemical because of the availability of other fumigants, including methyl bromide.
Managing soilborne pests
Three articles look at new approaches to managing soilborne pests without methyl bromide.
“It now seems likely that no single measure will suffice to meet the challenge of soilborne pathogens,” write Margaret Lloyd, UC Cooperative Extension advisor, and Tom Gordon, UC Davis professor in the Department of Plant Pathology, in this issue's Outlook. “Rather, a multi-faceted approach will be required, one that integrates advances in disease resistance through breeding with closer attention to the factors that influence the survival, activity and spread of pathogen populations in soil.” They make the case for using a suite of strategies to manage soilborne pathogens — including collective action among growers to help limit the spread of pathogens between fields.
A news item on research at the UC ANR Hansen Agricultural Research and Extension Center covers ongoing research on anaerobic soil disinfestation, a chemical-free technique that is being used in a growing number of commercial fields. Project scientist Amanda Hodson and UC Davis professor Edwin Lewis, both in the Department of Entomology and Nematology, review a variety of approaches to managing for soil health — in strawberries and other crops — as a pest suppression strategy.
Other soil fumigants
Fumigants other than methyl bromide, such as chloropicrin, remain widely used in California strawberry production. Rachael Goodhue, UC Davis professor in the Department of Agricultural and Resource Economics at UC Davis, examines how increasingly stringent buffer zone requirements for chloropicrin application have an uneven impact on growers, depending on their proximity to developed land. In another article, a group of UC Cooperative Extension and U.S. Department of Agriculture scientists report on the effectiveness of several fumigants at dosages lower than the maximum label rate.
Food safety and nutrient management on the farm
The issue also includes two research papers focused on general production practices for crops. One report discusses on-farm food safety practices based on a survey of produce growers. The researchers found that practices such as exclusion fencing and vegetation clearing, which may negatively impact wildlife, remain widespread despite a lack of clear evidence that they enhance food safety. Finally, Daniel Geisseler, UC Cooperative Extension specialist in the Department of Land, Air and Water Resources at UC Davis, and Gene Miyao, UC Cooperative Extension advisor, review the use of soil testing to guide the management of soil phosphorus and potassium in California cropping systems.
To read California Agriculture, a peer-reviewed journal of research in agricultural, human and natural resources published by UC Agriculture and Natural Resources, visit http://calag.ucanr.edu. For a free subscription, sign up on the website or write to calag@ucanr.edu.
View this story in Spanish:
¿Qué hará la industria de la fresa sin el bromuro de metilo? http://ucanr.edu/sites/Spanish/noticias/?uid=6887&ds=199. Video on UCANR Spanish YouTube: California Agriculture: el bromuro de metilo en cultivos de fresa https://www.youtube.com/watch?v=5D4FwLqjaLk.
The latest issue of California Agriculture is devoted entirely to forestry, starting with the editorial on 100 years of forestry at UC Berkeley by College of Natural Resources Dean Keith Gilless. Other articles are listed below.
Research news:
Fewer trees, more water, safer forests: The Sierra Nevada Watershed Ecosystem Enhancement Project is investigating how tree thinning — which is needed urgently in much of the Sierra Nevada due to long-term fire suppression — may increase the water yield from forested watersheds by as much as 10 percent. Monetizing this increased water yield, as well as other benefits from healthier forest ecosystems, could help fund forest management.
Forest thinning may increase water yield from the Sierra Nevada
Protecting oak woodlands: On California's North Coast, grassy oak woodlands are being invaded by stands of Douglas fir at an alarming rate. A UC ANR–led research team is working to understand the reasons why and guide efforts to reverse the trend.
Conifer encroachment study will inform efforts to preserve and restore North Coast oak woodlands
Peer-reviewed Research
Remote sensing: The powerful mapping capabilities of Lidar soon may be widely available to California forest managers as costs fall and the technology improves.
Mapping forests with Lidar provides flexible, accurate data with many uses
Maggi Kelly and Stefania Di Tommaso
Forest carbon: Private forests that are harvested and regenerated yield approximately 30 percent more carbon sequestration benefits than if they are left to grow.
Carbon calculator tracks the climate benefits of managed private forests
William C. Stewart and Benktesh D. Sharma
Forest management: A long-term study in the Sierra Nevada confirms the negative consequences of preferentially removing large trees.
Large-tree removal in a mixed-conifer forest halves productivity and increases white fir
Robert A. York
Post-fire ecology: Nearly 30 years after a burn at two sites in northeastern California, sagebrush had recovered fully and invasive grasses had diminished.
Post-fire vegetation dynamics of a sagebrush steppe community change significantly over time
Sara K. Hanna and Kenneth O. Fulgham
Community engagement: All sides of the Sierra Nevada forest management debate have learned from SNAMP. Can stakeholders help ensure research results are part of future management?
UC plays a crucial facilitating role in the Sierra Nevada Adaptive Management Project
Adriana Sulak, Lynn Huntsinger and Susan D. Kocher
Ecosystem Restoration: A cooperative meadow restoration plan that successfully engaged a diverse group of stakeholders is a model for future projects.
Cooperative, cross-boundary management facilitates large-scale ecosystem restoration efforts
Erin Kelly and Jonathan Kusel
Community Fire Safety: The collaborative partnership has improved fire safety at the urban-wildland interface in fire-prone communities of Plumas, Butte and Yuba counties and stopped major wildfires.
UC Cooperative Extension works with fire safe councils to reduce wildfires
Glenn A. Nader and Michael De Lasaux
The entire California Agriculture issue can be downloaded at http://californiaagriculture.ucanr.edu.
California Agriculture is a peer-reviewed journal of research in agricultural, human and natural resources published by the University of California Division of Agriculture and Natural Resources. For a free subscription, visit http://californiaagriculture.ucanr.edu, or write to calag@ucanr.edu.
An article in the current issue of California Agriculture, the peer-reviewed journal from the University of California Agriculture and Natural Resources, examines the spread of herbicide-resistant weeds in California and shows how UC researchers and Cooperative Extension specialists are helping growers to understand and manage the factors that drive it.
Five more articles in this special issue of California Agriculture highlight the work of UC Agriculture and Natural Resources on pests and diseases that threaten the state's people, agriculture and natural resources. The commitments to research and outreach profiled in the issue include the Endemic and Invasive Pests Strategic Initiative, the UC Statewide IPM Program and several successful collaborations with regulatory agencies and the agricultural community.
Diagnostics in animal health: How UC helps exclude and minimize impact of livestock pathogens
Whether it's pinkeye, bluetongue or poisonous plants, UC maintains a strong network of laboratories and field experts to protect livestock health in California.
Regional alliances of federal, state and university plant diagnostic labs work together to identify and control disease spread.
Managing newly established pests
Growers, scientists and regulators collaborate on European grapevine moth program
A regulatory program coordinated by government agencies, scientists and growers successfully contained an infestation that threatened California vineyards.
The 1999 arrival in California of a new Pierce's disease vector, the glassy-winged sharpshooter, posed a major new threat to California vineyards and orchards. A 15-year collaborative effort has successfully contained the sharpshooter and led to major improvements in our understanding of the biology of Pierce's disease, including promising advances in the development of disease-resistant grapevine lines.
Maintaining long-term management
Herbicide-resistant weeds challenge some signature cropping systems
Little or no crop rotation and limited herbicide options have contributed to the rise of herbicide-resistant weeds in orchards, vineyards and rice fields.
Over 35 years, integrated pest management has reduced pest risks and pesticide use
The UC Integrated Pest Management Program helps provide management solutions for invasive pests that destabilize IPM programs in agricultural and urban landscapes.
E-edition research article
The cost of the glassy-winged sharpshooter to California grape, citrus and nursery producers
The spread of the invasive insect in the late 1990s led to increased costs and changes in agricultural practices for grape, citrus and nursery producers.
These articles and the entire October-December 2014 issue are available at http://californiaagriculture.ucanr.edu.
California Agriculture is the University of California's peer-reviewed journal of research in agricultural, human and natural resources. For a free subscription, go to http://californiaagriculture.ucanr.edu or write to calag@ucanr.edu.
University of California Agriculture and Natural Resources is the bridge between local issues and the power of UC research. UC ANR's advisors, specialists and faculty bring practical, science-based answers to Californians. Visit ucanr.edu to learn more.
- Author: Debbie Thompson
New UC research shows recycled water is suitable for Napa vineyards, but adds chloride to Salinas Valley soil.
"This drought is unprecedented — we've never had such a lack of rainfall since we started keeping track," says Doug Parker, who directs UC ANR's California Institute for Water Resources and also leads UC ANR's Strategic Initiative on Water Quality, Quantity and Security. "Farmers are looking for ways they can stretch their water budget."
One way is irrigating vineyards with recycled wastewater from municipal waste treatment plants. California recycles only 7 percent of the 9 million acre-feet of urban wastewater produced per year, and the state wants to nearly quadruple that by 2030. Besides providing a source of irrigation water during drought, recycling water is cost-effective and reduces wastewater discharge to rivers.
To see if recycled water is suitable for use in Napa vineyards, UC Cooperative Extension researchers evaluated the quality of water treated by the Napa Sanitation District (NSD) as well as its impact on soil. They found that the quality of the recycled water was similar to that of other local sources of irrigation water. Additionally, in a vineyard that was irrigated with recycled water for 8 years, the soil did not accumulate salts or toxic ions, such as boron.
"Our work suggests that treated wastewater from the NSD is suitable for irrigation of vineyards over the long term," the researchers say.
One caveat is that the recycled water was relatively high in nitrogen. The higher soil nitrogen levels will be fine for many vineyards but, when needed, growers can easily reduce nitrogen by planting cover crops such as cereals and other grasses during the winter.
Also in this issue:
Recycled water increases chloride in Salinas Valley soil
Most growers in the northern Salinas Valley have irrigated their crops with recycled wastewater since 1998, raising concerns about salt accumulation in the soil. New research shows that since the year 2000, only a small amount of sodium has accumulated in the 12-inch deep rooting zone. In half of the fields studied, chloride has accumulated to levels that could affect yields of strawberry plants and leafy greens such as spinach. This chloride buildup may be due to the recent lack of winter rainfall, which normally washes salts out of the root zone, and could be mitigated by improving drainage and avoiding soil amendments that contain chloride.
Reducing runoff from alfalfa fields
Accounting for nearly 20 percent of total agricultural water use statewide, alfalfa is California's thirstiest crop — large amounts of irrigation water can be wasted as runoff. New UC research shows that alfalfa growers can reduce this runoff to a comparative trickle by using a mathematical model that predicts the advance of irrigation water across a field in combination with wireless sensors that track the water's advance. This new approach also frees growers from checking the irrigation status of fields in person, saving time and labor.
Predicting which plants will invade California
Most ornamental plants are happy to stay in gardens, but some jump the fence, invading wildlands and crowding out native plants. California has a wealth of native plants, about 3,400 species, but is also plagued by more than 1,500 species of invasive plants, many of which were introduced by the horticultural trade. New UC research identifies 186 ornamentals that have invaded Mediterranean areas in other parts of the world, and so are at high risk of becoming invasive here too. This work could help focus further risk assessments of imported ornamentals, as well as help land managers identify which species to watch for in wildlands.
The entire July-September 2014 issue can be downloaded at http://californiaagriculture.ucanr.edu.
California Agriculture is the University of California's peer-reviewed journal of research in agricultural, human and natural resources. For a free subscription, go to http://californiaagriculture.ucanr.edu or write to calag@ucanr.edu.
- Author: Pamela Kan-Rice
“A significant number of regions in California won't have groundwater available in another generation or two if we continue business as usual.” -- UC scientists Thomas Harter and Helen Dahlke
In the special edition of California Agriculture released today (July 16), UC Cooperative Extension specialist and UC Davis professor Thomas Harter and UC Davis professor Helen Dahlke call attention to the stress being placed on California's aquifers as well as the catastrophic consequences of not having this hidden resource available in future droughts.
In the University of California's premiere journal for agricultural research, the groundwater experts make the following key recommendations:
- Groundwater is most effectively managed at the local or regional basin level, with support from the state.
- Local groundwater management entities must be given better tools, such as clear mandates to assess, measure, monitor and allocate their groundwater and control its extraction.
- The definition of groundwater sustainability can be set at the state level and translated into specific actionable thresholds that must be enforced locally, with a credible threat of state enforcement should the local efforts be unsuccessful.
- Much better data collection, analysis, reporting and data integration are needed to provide transparency, to support local management efforts and to properly inform the public. This requires much stronger planning and support within the DWR and SWB.
“Fundamentally, even more needs to be done," Harter and Dahlke write. "Local land-use decisions on urban and agricultural development, which have critical impacts on groundwater resources, must be consistent with groundwater management objectives. This will require significant communication between land-use and groundwater managers. Effective integration with water quality management and surface water management efforts, which are governed separately, is also required. And none of these efforts can occur without sustained funding through a mix of local and state sources.”
In their outlook article, Harter and Dahlke also explore one of the most promising ideas to protect our aquifers: groundwater banking.
The idea is that during storms or flood control releases, excess surface water could be directed from streams via existing water conveyance systems onto dormant or fallow agricultural fields, which would then serve as infiltration basins. Solutions need to be developed to add significant recharge to California's aquifers, often during relatively short periods when excess surface water is available.
A 3-year project, funded by UC Division of Agriculture and Natural Resources, aims to look at the feasibility of such groundwater recharge activities by setting up pilot groundwater recharge field experiments, which would provide valuable data to address concerns about the costs and risks to crops, the influence these projects may have on groundwater levels and flows, and the possibility of recharging contaminated water or degrading groundwater quality by leaching contaminants such as nitrate from the vadose zone. Data collected could serve as a foundation for developing economic incentives at the local, state or federal level to acknowledge the landowner's service to the local community and California's water supply reliability.
To read their entire article, "Out of sight but not out of mind: California refocuses on groundwater,” and the special "Water efficiency" edition of California Agriculture, visit http://californiaagriculture.ucanr.edu and http://ucanr.edu/repositoryfiles/cav6803p54-136027.pdf.
Further reading:
UC Cooperative Extension Groundwater Program http://groundwater.ucdavis.edu
Helen Dahlke's groundwater banking project http://dahlke.ucdavis.edu/research/groundwater-banking
California Water Action Plan: Improving Groundwater Management (links to state policy and emerging legislation) http://groundwater.ca.gov
California Department of Water Resources report to the Governor's Drought Task Force http://www.water.ca.gov/waterconditions/docs/Drought_Response-Groundwater_Basins_April30_Final_BC.pdf
California Water Plan Update 2013 http://www.waterplan.water.ca.gov/cwpu2013
Association of California Water Agencies Recommendations for Achieving Groundwater Sustainability http://www.acwa.com/sites/default/files/post/groundwater/2014/04/final_acwa-groundwater-sustainability-recommendations.pdf
