Posts Tagged: soil fumigant issues
One of my research focus areas over the past few years has been related to soil fumigation issues, specifically focused on methyl bromide alternatives for the tree and vine nursery industry. I described some of this nursery work in a post late last year. Today I wanted to share a brief description and links containing a more overarching view of methyl bromide alternatives related research in California, Oregon, and Washington.
With the support of USDA-ARS, a five-year program was initiated in 2006 to support research, demonstration, and extension projects in western cropping systems heavily reliant on preplant soil fumigation with methyl bromide. These included several nursery systems (decideous tree and vine, sweet potato slips, cut flowers and bulbs, forest seedlings) production systems (orchard and vineyard replanting, strawberry, etc) as well as controlling atmospheric emissions of fumigants.
As these projects reach the end of the five-year horizan, we started building a website to serve as a bit of a clearinghouse for information on the issues and research results. Last week in Orlando, FL at the Annual Research Conference on Integrated Methyl Bromide Alternatives and Emission Reductions (who names these things anyway?), I coauthored a paper and poster with one of my USDA-ARS collegeues on our extension website and related outreach efforts. A pdf copy of the poster is attached at the bottom of this post or can be found here.
Better yet, you can visit the USDA-ARS Pacific Area-Wide Methyl Bromide Alternatives Program website (ok, I take the blame for the website name). There are about 100 pages of information and links to a lot of more in-depth information by several multidisciplinary research teams. Some of these pages are still being developed or finalized but I think this site is good start to explaining the methyl bromide issues, research successes, and continuting challenges in California and other western states.
soil fumigation extension Hanson UCD
I'm sure more information will be available over the next few day from news outlets and online sources but for now, here's one reposted from the LA Times below or at this link.
By Steve Chawkins and Diana Marcum, Los Angeles Times
March 21, 2012, 5:35 p.m.
Methyl iodide, meant to replace an ozone-depleting fumigant being phased out by an international treaty, was believed to have little effect on air quality. But some scientists say it can cause cancer, brain damage and miscarriages among workers who handle it and can be a threat to ground water.
In California, which produces 90% of the nation's strawberries, environmental advocates reacted enthusiastically Wednesday to the announcement by Tokyo-based Arysta LifeScience Inc.
"This way is more powerful than a court victory. It's a concession. It's them walking," said Greg Loarie, lead attorney in a lawsuit attacking the process California used to approve the chemical in 2010.
"Today I'm really happy," said 19-year-old Gabriela Rincon, who joined marches against the chemical and told her parents, both pickers in the Salinas area, about the risk. "It feels like someone finally listened to us about something really important."
An Arysta spokeswoman said the decision late Tuesday to abandon U.S. production and marketing of the company's trademarked Midas fumigant was financial. Arysta will continue to market the chemical outside the U.S.
In 2011, the first full year it was available as a replacement for methyl bromide, only one strawberry grower used it, on a small plot outside Santa Maria, according to the California Strawberry Commission.
Several pepper farmers in the Central Valley also reportedly applied the chemical. Its chilly reception among growers contrasted sharply with the urgency expressed by state officials in 2010, when then-Gov. Arnold Schwarzenegger deemed its approval an "emergency."
For some growers, the legal risk of using a compound that had generated intense notoriety proved too great.
"Growers want to grow, not spend time on litigation," said John Krist, chief executive of the Farm Bureau of Ventura County.
Krist said that in Ventura County, where strawberries bring in more revenue than any other crop, growers believed that "the first one of us to use it publicly is going to get dragged into court."
"Despite extremely thorough evaluation and research, and stringent restrictions on its use, you still had a lot of people who were convinced this was a material that couldn't be used safely," he said. "It has tremendous potential value and utility — but nobody was willing to be a pioneer."
Methyl iodide kills fungal pathogens and other organisms in the soil that are harmful to strawberry plants. It is more expensive than other fumigants, and the state requires a bigger buffer zone between farms that use it and the nearest residential areas.
Its approval on both federal and state levels came despite a letter from more than 50 scientists, including five Nobel laureates, calling the compound "one of the most toxic chemicals used in manufacturing."
Before California approved methyl iodide, an independent scientific review said the chemical could alter DNA and taint groundwater. Still, the state approved it, saying it was safe if used correctly and was urgently needed by strawberry growers.
On Wednesday, some in the industry said the decision would put the U.S., particularly California, at a competitive disadvantage because methyl iodide is licensed for use in eight other countries, including Mexico.
Growers are treating their fields with a variety of chemicals, including limited amounts of methyl bromide. No deadline has been set for an end to methyl bromide application, but federal regulators must approve its use on a year-to-year basis. More strawberries are being grown organically, but they yield 25% to 30% less than conventional berries.
Meanwhile, the state strawberry commission is researching ways to grow berries without soil, using rice hulls and coconut fragments. Aided by a recent $500,000 grant from the state Department of Pest Regulation, scientists are also looking into killing pests with steam, concentrated sunlight and mustard seed.
One of my major areas of research the past few years has been related to alternatives to methyl bromide fumigation in perennial crop nurseries. A list of recent posts on soil fumigation research and issues is available. Some specific research areas have included reducing atmospheric emissions of methyl bromide alternatives and on alternative fumigants such as methyl iodide.
Today, I thought I'd share some basic information on the nursery cropping system as well as two recent research reports on our work. The perennial crop nursery system is a fairly unique cropping system where many of our orchard trees, backyard trees, grapevines, and garden roses are grown in the ground for a year or two and then dug up and sold as "bare root" plants. Most of these trees and vines are grown as scions budded onto a rootstock so that the resulting plants have good market characteristics of the harvested commodity as well as a root system that is vigorous and well adapted to the soil and environment in the production orchard or vineyard.
Nursery stock is sometimes referred to as "plants for planting" in the regulatory world. Because of very high requirements (and expectations) for planting stock free of plant parasitic nematodes and disease pathoges, most perennial crop nurseries in the state are fumigated with a preplant soil fumigant such as methyl bromide or 1,3-dichloropropene before each planting cycle (usually about once every 4 years in the crop rotation). One of the preferred fumigants for this purpose, methyl bromide, is being phased out due to its impact on stratospheric ozone. More details on this issue and on the phase out can be found at http://www.epa.gov/ozone/mbr/
In response to the phaseout of methyl bromide, a lot of research has been conducted trying to find alternative strategies and approaches that are environmentally acceptable, economically viable, and provide similar levels of broad spectrum pest control - this is a pretty tall order! For the past several years, I have been involved in a series of projects to test and demonstrate alternative fumigants that meet nematode certification requirements as part of the USDA-ARS Pacific Areawide Program for Integrated Methyl Bromide Alternatives.
Recently, we attended the Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions. A lot of great information from researchers around the world is availabe at the conference website (MBAO.org). This year in San Diego, I gave an update on the Nursery Sector Project of the Pacific Areawide Program and Joy Abit presented a poster on recent herbicide testing we've done in tree nurseries. Our proceedings papers as well as the presentations are available online for those that are interested:
MB Alternatives for the California Perenial Nursery Industry - a PAW Project Update (Proceedings) (Presentation)
Weed Control Efficacy and Rootstock Safety to Herbicides in Fruit and Nut Tree Nursery Production (Proceedings) (Poster)
UC scientists now report that use of totally impermeable film in strawberry fields can improve the effectiveness of a widely-used MB alternative known as 1,3-D (1,3, dichloropropene). Use of the film reduces the amount of 1,3-D needed to maintain yields, while lowering field emissions overall.
The strawberry industry is highly dependent on soil fumigation to control pests and maintain high yields. The methyl bromide alternative, 1,3-D, can be used only in certain quantities, due to air quality concerns.
In a recent trial, totally impermeable film (TIF) was laid out over Salinas fields to prevent the fumigant from leaking. The new film was compared with the standard film used by growers. Fumigant concentrations under TIF were 46 percent to 54 percent higher than under standard film, and the higher concentrations were correlated with higher strawberry yields and better weed control. Scientists report these findings in detail in the October–December 2011 electronic edition of the University of California’s California Agriculture journal.
Impermeable films have three benefits, according to lead author Steven Fennimore, UC Cooperative Extension specialist and weed scientist in UC Davis Department of Plant Sciences. The films trap the fumigant in the soil for a longer time and thereby increase its effectiveness; they reduce fumigant emissions, which after reacting with nitrogen oxides, can convert to ground-level ozone; and they reduce the amount of fumigant needed for effective pest control.
Emissions are a chief concern. Methyl bromide, a widely used fumigant in combination with chloropicrin, has been phased out since 2005 because it is an ozone-depleting substance targeted by the Montreal Protocol (a global treaty to control ozone depletion) and the U.S. Clean Air Act. However, it is still being used in some California strawberry fields under a critical-use exemption. Restrictions on the use of 1,3-D to 90,250 pounds per 36-square-mile township (called the township cap) leave few other options for growers in key strawberry production areas near densely populated areas.
Comparing TIF with standard film, and methyl bromide plus chloropicrin with varying amounts of 1,3-D plus chloropicrin, the scientists rated the effectiveness of TIF. The results, writes Fennimore, suggest that to achieve fruit yield and weed control similar to methyl bromide and chloropicrin, 33 percent less 1,3-D plus chloropicrin is needed under TIF than standard films.
TIF may ease some of the burdens of fumigant regulations on end-users, as well as ease concerns of the general public about exposure to fumigants, he concludes.
The research article “Totally impermeable film retains fumigants, allowing lower application rates in strawberry” can be viewed and downloaded at http://californiaagriculture.ucanr.org/landingpage.cfm?article=ca.E.v065n04p211&fulltext=yes.
I gave an overview presentation on my research program today as part of the Plant Science Departmental Seminar series at UC Davis. I thought I'd post it here for several reasons:
1. There might be someone out there who is just dying to know what I do - here you go!
2. I thought the software that I used (prezi.com) was pretty slick and made a nice presentation (gasp - not PowerPoint?!).
3. I spent a bunch of time learning about this (pretty easy to use) software and wanted to see how the "embed" function worked (HTML code is generated and makes it easy to embed the presentation in online vehicles like blogs, webpages, and social media tools).
4. A "program overview" presentation has limited utility so I might as well use again here before I shelve it.
So, here is an overview of my program - click on the triangle-shaped button to move forward. You can click "more" in the lower right if you want to view in full screen mode. Thanks to the collaborators and cooperators who generated some of these data and to the many support folks who have worked on these projects.