More Webinars and Trainings We Recommend

High Tunnels Webinar
April 26
2:00pm – 3:00pm (Eastern Time)
Online Webinar
Registration Information Here

Participants will learn about techniques used in high tunnel cropping systems to address issues with salinity, nutrient management, and pest management. For more information and to view the event online you can visit the event page here.


Healthy Soils Initiative Update
April 20

12:00pm – 1:00pm (Pacific Time)

Online Webinar 

Register Here

Renata Brillinger, Executive Director of CalCAN, the California Climate and Agriculture Network, joins the CCOF Foundation (California Certified Organic Farmers) in presenting the latest news on 2017 funding opportunities for ranchers and farmers interested in applying healthy soils practices on their land.

Making Cover Crops Work for No-Till Vegetables
April 19
9:00am – 1:45pm (Eastern Time)
Charleston, SC

Register Here The cost of this training is $15.  Lunch will be provided and each participant will receive a copy of the book “Managing Cover Crops Profitably”.  For more visit their website.
Fumigants and non-fumigant alternatives: regulatory and research updates
April 28
8:00am – 12:00pm (Pacific Time)
Ventura, CA

Register HereSpeakers from the Ventura County Ag Commission, California Strawberry Commission and University experts will provide updates and insight on fumigant regulations and updates.

Annual Santa Maria Strawberry Field Day
May 10

8:00am – 1:30pm (Pacific Time)
Santa Maria, CA
Host: Surendra Dara, Ph.D.
Strawberry and Crop Advisor for Santa Barbara and San Luis Obispo Counties

Meeting You


What can we say about the World Ag Expo? It’s awesome to be among the leaders of agriculture and talk to people interested in using vegetable based organic methods for optimizing the soil on their farms, orchards, and vineyards. To stand beside Massey Ferguson and John Deere reps and have something to offer that has been proven to work — that’s exciting!

We especially want to contribute to the success of growers who feed California fruits and vegetables to the world, and it was good to meet you! Lots of people purchased our attractive T-shirts and hoodies, and if you see them around, ask about ASD and Mustard Meal. We talked people’s ears off and handed out lots of brochures and free samples, so there should be some new experts and advocates among you. It’s not that hard to understand — these alternatives to fumigation help your microbes maintain balance so your plants can grow healthy and produce the fruits and vegetables we love. It’s good for business and good for your bottom line.


Lucy, Matt, Taylor and Fernando

Under Snow


Catching a few minutes of winter wonderland at the ski resort 15 minutes up the hill from Wenatchee, Taylor Hoover raves about this beautiful fruit growing region following the Washington State Tree Fruit Association meeting and the North West Horticulture Expo the first week in December.


Winter is a good time to think about your plans for the coming season using PESCADERO GOLD Mustard Seed Meal. You could contemplate the benefits of a mustard cover crop (and we can talk you through it and find you some certified seed) OR plan for a shorter plant back — 3 weeks minimum when the ground thaws next spring.

What a pleasure to meet so many farmers we had talked with on the phone over the last two seasons. USDA research in the Wenatchee area is followed closely by these dedicated orchard keepers, and we were busy answering questions about mustard seed meal and its availability. Fortunately, we have contracted with a friendly crush facility in Sunnyside, so shipping is no longer a financial barrier for Washington farmers.

We also recommend using mustard seed meal in the fall after an older orchard is removed. PESCADERO GOLD does its work in the first three weeks after irrigation or a rain event. Then it settles in under the snow,  its soil nutrients (NPK of 4.5 – 1.5 – 1.15) waiting to feed new trees come spring.

Taylor didn’t win the Gator or the chainsaw or the drone offered  via raffles by other companies at the trade show, but he did offer to return to Wenatchee, whenever invited, to help strategize success for a young orchard.

Mustard Seed Meal in the Orchard



Apple orchards along the Washington by-ways

In the past Bill Piexoto used to tell people that he could no longer plant new apple trees in his orchard – until, that is, he found out about mustard seed meal. Orchard soils, in the process of maintaining healthy trees over time, become imbalanced and often cannot support new saplings without special treatment.

Conventional farmers fumigate their orchard soil to ensure a good start for new trees. What we’ve learned in the last decade, thanks to breakthroughs in DNA sequencing and genomic research, is that  fumigation is like chemotherapy – it actually kills all the life in the soil microbiome for the short-term gain of killing a few bad bugs. We are starting to wonder if there’s something wrong with this approach – aren’t we sophisticated enough to update soil care?


Piexoto participating in trials with Farm Fuel staff

Piexoto has managed organic orchards since the 1980’s in Corralitos, Santa Cruz County, California. He knows there is a symbiotic relationship between plant roots and the soil microbiome – each feeding the other. Some older trees provide a diminishing amount of healthful photosynthetic substances (sugars) to exchange with microbes in the soil for water and nutrients. So they become unhealthy and are removed. The microbes left behind in the soil that were dependent on those old tree roots are ready to devour a young sapling, sucking the life out of its roots before it has a chance to develop.

Replant.Disease.Peach.2     Trunk.Replant.Disease.2

Typical symptoms of replant disease

What is a farmer to do if he or she farms organically? According to Piexoto, there was no point in replanting into the same soil. And in order to maintain his orchard as certified organic, he is prohibited from chemical fumigation. Finding mustard seed meal was a welcome discovery.

When applied at the optimal rate of about 1-3 tons per acre (yes there is math involved*), crushed mustard seed meal, derived at Farm Fuel from a proprietary blend of pressed mustard seeds with the oil removed, revitalizes and rebalances the soil, when mixed with water, due to an explosion of isothiocyanates.

Just like the heat you feel on your tongue when you dip a bite of sushi into wasabi (which is derived from the horse radish root, another brassica), the soil in the orchard row gets a flush of mustard heat when first irrigated.

This flush peaks after about 12 hours, according to research, and then over two week’s time, the mustard meal turns into a healthy vegetable-based organic food for the kinds of microbes that rebalance your orchard soil.

For those in regions where dry and depleted hilltops are being replanted with organic orchards and vineyards, mustard seed meal can kick-start the soil to a high level of productivity in combination with compost blended with trace minerals and perhaps mycorrhizal fungi. Many of Farm Fuel’s customers make interesting blends, including Jeff Chasser at The Soil Makers ( and Maine Potato Lady Alison LaCourse. And Cynthia Sandberg of Love Apple Farms regularly recommends mustard seed meal as an essential ingredient in her double-digging soil building recipe.


Dave Benner of Adams County, PA, giving a tour of some of the orchards where he uses Mustard Seed Meal

For those wishing to replace chemical fumigation in conventional systems (like Dave Benner in Adams County, Pennsylvania, pictured), mustard seed meal, when applied and cultivated deeply two weeks to six months in advance of planting, can awaken a healthy microbial community in the orchard. As a farmer, instead of going to war with bugs and pathogens, you’re building the soil’s immune system.

It’s a different approach to farming – working with nature rather than fighting against threats – to produce a healthy bottom line. As Reuben Stolzfus, of Lancaster Ag Products, says: “I don’t want to kill things. Our passion is agriculture and promoting healthy living through farming and gardening. Our great desire is to use our company to  touch individual people at the heart level, help families to better health, and challenge all of us to leave a greener tomorrow than what was given to us.”

Nature has something to exchange with us – healthy plants and foods for our table when we feed the soil its own balanced feast.

A thriving farm system is almost a closed-loop system except that the plant materials we harvest as fruits and vegetables take some nutrients with them out of the loop. If eaters buy from farmers who are paying attention to their soil, their produce will contain the trace minerals and nutrients we need to thrive. Replacing this nutrition year after year in an orchard is an art and a practice that can be learned and applied to new plantings.

Maintaining orchard soils after the initial planting can include cover cropping between rows, which provides a diversity of foods to the soil microbes, depending on which cover crop cocktails you choose to serve. As Cover Crop Coach Steve Groff says “Just like you need to choose your own spouse, you need to choose your own cover crop blend. People may give you suggestions, but it’s up to you.”

Great places to look for cover crop blend suggestions include the Lancaster Ag Products catalog, Penn State’s cover crop research results website, and their newsletter. You can also talk with Steve Groff, the Cover Crop Coach. Find him on his website:

Not common in California until recent drought years pushed farmers to retain soil moisture, cover cropping has multiple benefits: it can shade out weeds, attract beneficial insects, keep soil loose, prevent erosion, and partner with microbes and worms in the formation of healthy soil aggregates which help soils retain moisture more effectively. It also has the added benefit of sequestering carbon in the soil. The deeper your soil organic matter, the more carbon you are sequestering.

Side dressing with mustard seed meal over the years, especially just before rain, gives mature trees an invigorating jolt of isothiocyanates for rebalancing. But it is really not necessary to till and disturb healthy microbial communities between tree rows, as long as you keep them fed with cover crop root exudates, mulched to retain moisture, and you observe carefully what’s going on with the leaves, blossoms, and bark of your trees.


*This comes out to 1 lb per 7.26 sq feet at the 3-ton per acre rate. You can figure the orchard rows are about one-third of the acreage, depending on your set-up.

Can You See the Difference?

The raised bed to the right received a heavy dose of Pescadero Gold Mustard Meal Fertilizer to refurbish the soil after it hosted tomatoes last season. The bed to the left did not have any mustard meal incorporated into the soil as it produced small lettuces throughout the winter, and there was no chance to stir in the pellets. These zephyr squash plants were grown from seed and sprouted exactly the same day. Can you see the size difference with our Pescadero Gold? Amazing! Even to this gardener, who is already convinced of mustard meal’s veracity as a great source of nitrogen for the green growth of your plants.

See the Difference (2)

Pescadero Gold helps get plants off to a good start so they can produce excellent blossoms and fruit. In this case, a nice home-made compost was also stirred into both beds, enhancing other nutrients besides nitrogen. With minimal watering, here’s hoping for a great harvest — starting soon! (And it’s only May!!)


The Good Guys and Gals of Watsonville


Watsonville garden aims to grow community, healthy food

Neighbors and other community members work together to fill the 27 raised garden boxes installed next to River Park on Friday through a partnership of Mesa Verde Gardens and the city of Watsonville. (Shmuel Thaler — Santa Cruz Sentinel) 

By Donna Jones, Santa Cruz Sentinel


Community members work together to get the garden planters in place Friday. By the end March, Mesa Verde Gardens will have opened 10 gardens, providing 250 families space to grown their own organic vegetables. (Shmuel Thaler — Santa Cruz Sentinel)


WATSONVILLE >> The neighborhood around River Park is dense with apartments crowded with families living paycheck to paycheck. There’s little room for gardening, and little cash to put organic fruits and vegetables on the table.

The 27 raised beds newly lined up at River Park on Front Street will change that, giving families a place to grow their own organic produce.

“It’s an opportunity for people to come together, to get to know one another, and at the same time have healthy food,” said Councilwoman Karina Cervantez, who represents the neighborhood.

The idea to build the community garden developed out of conversation Cervantez had with nonprofitMesa Verde Gardens founder Ana Rasmussen.

Cervantez said some of her constituents complained that a vacant lot, once home to the city’s mobile Neighborhood Services Division, was creating public safety concerns. Then she found out about Rasmussen’s work organizing community gardens, and an idea emerged.

“I thought it was a great project to pursue,” Cervantez said.

The project wasn’t without challenges. Rasmussen said the land was a parking lot, the soil buried under 5 feet of fill packed hard as concrete. Planter boxes filled with healthy soil were the only way to go, but she had never set up a community garden with them.

Materials — wood and soil — cost $8,000, eight times the normal expense for establishing an in-ground garden. Fencing will run another $3,000, money that’s still being raised.

Fortunately, Cervantez said volunteers stepped forward to donate labor. Workers from Home Depot built the 4-by-20-foot boxes Tuesday. Friday, a crew from Driscoll’s Strawberry Associates Inc. filled them with a mixture of dirt, compost and sand.

Residents will pay $8 a month for a box, which covers water. Rasmussen estimated they’ll be able to harvest an average of 30 pounds of produce a month, May through October.

Since its founding in 2011, Mesa Verde Gardens has gone from one community garden serving 30 families to eight serving 250 families, including the three that area coming online this spring. Most are in Watsonville; one is in Live Oak.

In addition to the River Park venture, the nonprofit has entered into a partnership with the Pajaro Valley Unified School District to start gardens at Rolling Hills Middle School and Pajaro Middle School. Rasmussen said expects to start planting at the schools in April.

Mesa Verde also has planted 115 fruit trees, the bulk at a community orchard on a church-owned property on Alta Vista Drive.

Rasmussen has set a goal of establishing 100 community gardens across the county.

“More people having organic food, that’s the calling,” she said.

Mesa Verde Gardens

What: Nonprofit organizer of organic community gardens.

Why: To provide low-income families the means to grow their own food.

Where: Watsonville and Live Oak, goal is to establish 100 gardens countywide.


Thanks for Great Coverage, Civil Eats

The Future Strawberry: Will the Loss of a Major Pesticide Help the Industry to Go Green?

Coward.Berry.CropWhen it comes to growing strawberries, Farm Fuel, Inc., a Watsonville, California-based company, is on the cutting edge.

The company grows wild and domesticated mustard and lightly processes the harvest into mustard meal, a soil amendment. They also work with farmers on a technique called Anaerobic Soil Disinfestation (ASD). This precise farming technique involves applying a combination of water and carbon-rich material (think rice bran, grape pomace, mustard meal, and molasses), and then wrapping the soil in plastic. Under the plastic, the ingredients combine to create anaerobic conditions.

The idea with both of these approaches is to kill the organisms that cause the long list of diseases that plague strawberry farmers–without pesticides or fumigants (a form of pesticide that treats the soil before anything is even planted). Why the search for alternatives?

“As pesticide use becomes more restricted, growers have a greater need for solutions that are effective and affordable,” says Farm Fuel CEO and research director Stefanie Bourcier, who has received sizable grants to work with both organic and conventional farmers on these non-toxic techniques. “Ultimately, ASD and mustard meal offer both organic and conventional growers more options.”

The restrictions Bourcier is talking about are no small change. For over 40 years, U.S. strawberry farms–88 percent of which are in California–have relied on methyl bromide, the pesticide that works like a “magic bullet” to control diseases, persistent pests, and weeds. Methyl bromide has made it possible for growers to blanket coastal communities—from Santa Cruz south to Ventura County—with acres of perfect red berries that sell for as little as $2 to $3 a basket.

Now, after a very long, gradual phase out, this fumigant–also a potent neurotoxin, known for affecting the health of populations living close to strawberry fields and a contributor to the disappearance of the Dead Sea–will no longer be in use by 2017.

Methyl bromide sterilizes the soil by killing off virtually all micro-organisms, good and bad. But the chemical also contributes to the thinning of the stratospheric ozone layer when it evaporates during application. For this reason, thanks to the internationally binding Montreal Protocol, it has been gradually disappearing from the marketplace since 1993.

Now, most conventional growers–many of whom say there are no other reliable methods to eradicate pests and diseases–are scrambling for other options. Farmers and regulators have invested considerable resources into other fumigants, including the highly controversial methyl iodide—another known carcinogen and neurotoxin that is considered one of the most toxic chemicals on earth. But after public uproar, the manufacturer, Arysta LifeScience Corporation, withdrew it from the market in 2012.

And while other chemicals are plentiful in the marketplace, some advocates of alternative farming methods see a positive side to the phase out: New organic and agroecological methods–like the ones Farm Fuel is working on–are on the rise in the $2.6 billion industry.


A Real Sea Change? Or Just Different Pesticides?

While the European Union phased out methyl bromide completely in 2013, the Environmental Protection Agency (EPA) has been granting so-called critical use exemptions (CUEs) since 2005. These have been granted whenever an industry argues that not using methyl bromide would create “significant market disruptions” and when there are “no technically or economically feasible alternatives or substitutes.” But after 2016, CUEs will no longer be an option.

For California growers, this change is worrisome. Today, strawberry farms and nurseries account for nearly all methyl bromide used in agriculture. But they’ve only been granted a CUE for 412 tons this year, enough to treat 8,000 acres, or 20 percent of the 40,000 acres planted in strawberries, according to Carolyn O’Donnell, Communication Director at the California Strawberry Commission (CSC).

In 2016, that number will drop to 255 tons–enough for only around 9 percent of the current strawberry acreage.

To help growers make the inevitable transition, University of California and U.S. Department of Agriculture (USDA) researchers have spent several years testing methyl bromide alternatives, both chemical and biological, with well over $5 million in grants.

Professor Carol Shennan, an agroecologist at the University of California, Santa Cruz, is at the forefront of the research with multiple year grants from the USDA to study Anaerobic Soil Disinfestation at the farm scale. Over 10 years, Dr. Shennan and lead researcher Dr. Joji Muramoto have seen positive results with field tests on farms around the state. In fact, a government document notes that, “These experimental trials have shown good disease suppression and fruit yields comparable to methyl bromide treatments and other chemical fumigants.”

Farm Fuel brought ASD to market in 2011, which was its first commercial introduction. In 2013, California’s Department of Pesticide Regulation (DPR) awarded the company a three-year grant to introduce conventional growers to the non-toxic alternative. Currently, the company has 22 trial sites across California and another 28 commercial clients. It estimates that about 25 percent of the new acreage it treated in 2014 was on conventional farms. Farm Fuel also claims that it is cost effective, with a per acre cost of $2,700 compared to $3,900 or more for methyl bromide.

Despite these efforts, most conventional growers will begin using other fumigants. In particular, the EPA recommends as substitutes chloropicrin and 1,3-D, and combinations of the two with other chemicals. Neither is considered as effective as methyl bromide and both have negative health impacts.

After World War I, leftover stockpiles of chloropicrin—a weapon then nicknamed “vomiting gas”—were directed to agricultural use. Although its use is on the rise in the U.S., chloropicrin was phased out in Europe in 2013 due to respiratory health effects. The other go-to fumigant is 1,3-D, a known carcinogen produced by Dow Chemical. The DPR outlawed 1,3-D in 1990, but allowed it back on the market in 2004 with restrictions, anticipating its need in light of the phase-out of methyl bromide.

DPR Director Brian Leahy believes that ASD shows promise and he says that the department is actively committed to helping California farmers find less toxic ways to tackle soilborne pests and reduce their use of chemical fumigants. Leahy, a former organic rice farmer, said in a recent email exchange: “It is no secret that the department has and continues to take a long hard look at fumigants to ensure they are used in a protective manner. DPR believes the right to farm does not mean the right to cause harm.”

“Slowly but surely the fumigant tools are going away,” says the California Strawberry Commission’s O’Donnell. The Commission also received a grant from DPR to study ASD in 2014.

As O’Donnell sees it there is no one-size-fits-all solution to the pests that plague strawberry growers, but adding ASD to the toolbox is good for all farmers. “What is coming out of the research is essentially a cookbook full of recipes,” says O’Donnell. “‘If you have this soil type and these types of disease organisms, then these are the materials and methods you need to use,’ and so on.”

O’Donnell says that strawberry farmers are already in the habit of trying out new techniques on small sections of their fields—and that 20 percent of conventional growers also have organic operations. Plus, she says, “Anyone who’s working on strawberries—they’re all talking to each other.” CSC also hosts “field days” to help farmers connect to scientists.

However, O’Donnell is hesitant to embrace biological controls because she says it’s unclear whether they’ll be able to perform as consistently as fumigants over the long term.

What farmers need—or want—is another magic bullet. O’Donnell, whose organization represents approximately 400 farmers, points to the up-front investment strawberry farmers make, spending up to $20,000 per acre for the land, plants, fertilizer, etc. before they harvest a single berry. “If your crop peters out, you lose your investment—and sometimes your house or your business.” In other words, farmers have to be sure they’ll protect their investment or they won’t adopt new methods.

What About Organic?

Some farmers have been growing strawberries for years without methyl bromide. Take Jim Cochran, president of Swanton Berry Farm, a 75-acre farm in Davenport, just north of Santa Cruz. Cochran is also the first farmer to grow organic strawberries in the state. He sits on the board of directors at Farm Fuel and is part of the company’s ASD trials along with seven other strawberry farms, in collaboration with the Center for Agroecology & Sustainable Food Systems at U.C. Santa Cruz.

Like any strawberry farmer, Cochran is concerned with pests and diseases and he is interested in ASD. However, for over 30 years he has relied on traditional organic practices such as adding compost to his soil and crop rotations. Each field gets planted in strawberries just once every five or six years. During other years the fields are planted with crops like cauliflower or broccoli—which are modestly profitable—or the fields are fallow with cover crops like alfalfa. On the other hand, conventional growers who rely on chemical fumigants grow strawberries in the same field every other year.

“The multi-crop organic farm is vastly more complex than the single crop chemical strawberry farm. It requires much more management,” says Cochran. Crop rotation and organic methods are expensive and the yields are generally a little lower. “It’s not easy. What we’re up against is people who use chemicals and produce strawberries at $2.50 a basket and can still be quite profitable,” he says.

Amigo Cantisano, a leading organics advisor who helped found the Ecological Farming Association and California Certified Organic Farmers (CCOF), says that ASD is “an increasingly viable alternative to methyl bromide, and that’s a good thing.” But he worries that fumigants allow farmers not to “deal with soil biologically in a holistic way.”

As Cantisano sees it, controls—whether they are chemical or biological—allow farmers to forego building up the necessary soil foodweb. And fungicides wipe out soil flora, which create resistance to the very pathogens methyl bromide is used to kill. “The lack of a long-term crop rotation system eliminates the opportunity for the soil to cleanse itself biologically,” he says.

Of course, it’s not just conventional growers who rely on methyl bromide. While organic farmers do not use it in the fields, their certified pest-free nursery “starts” (baby plants) are grown in soil sterilized with methyl bromide, just like conventional growers. This is legal for certified organic farms, and the justification is that even one diseased start could ruin an entire crop.

According to Lisa Bunin, Organic Policy Director at the Center for Food Safety (CFS), “Both stages in the strawberry production process use enormous amounts of methyl bromide, and both represent critical junctures in the supply chain that need to figure out alternative production strategies.” According to a recent in-depth report by the Center for Investigative Reporting, CFS is leading a project to grow an experimental nursery crop of organic strawberry starts in Central California, and late last year, six organic farms planted those starts in soil for the first time.

What Lies Ahead?

While the DPR will clearly continue to allow—and indeed support—the use of chemical fumigants, Director Leahy is cognizant of the bigger picture. “In order to better understand pest control for any crop, California needs to better understand the soil ecosystem and how pests behave,” he says. “This requires a major public investment and dedicated research.”

Meanwhile, it’s likely that companies like Farm Fuel will gradually make inroads into the market as they develop relationships with the many curious farmers willing to give ASD and other biological approaches a try.

Back in 1996–just a couple years after the Montreal Protocol’s phase-out went into effect–some individuals at the EPA were already talking about non-chemical approaches. In a paper they released that year, the officials wrote: “Organic strawberry production is an effective integrated approach that offers an alternative to methyl bromide use for California strawberries.” Sometimes we have to look back to look forward.

Photo: Interns plant strawberry starts in an ASD trial field at the Center for Agroecology & Sustainable Food Systems at U.C. Santa Cruz (Brandon Blackburn).

Article by Jillian Steinberger


Bumper Crop in the Student Garden with Mustard Meal Donation

Report from Garden Advisor Jean Mahoney
Our 6th, 7th and 8th grade students working in the Branciforte Middle
B40.Jr.Hi.Garden (2)School Garden have used Pescadero Gold Mustard Meal with both our Spring and Fall Crops in 2014.  The addition of of Pescadero Gold has enhanced our  garden beds and helped us harvest bumper crops of tomatoes, popcorn, cilantro, and pole beans.  We noticed big changes in the health and tilth of our soil in the beds where the mustard meal was used. We added it before we planted, and also saw that the soil held moisture well.  That’s important in these drought years. When the Pescadero Gold’s bag was opened, students could tell right away where the meal came from.  One student remarked, “Take me out to the ballgame!”  Others were amazed that the mustard meal did, indeed smell like mustard.  Thanks for your generous donation to our student’s garden and their education as organic farmers.

Amazing mustard recipe interview

mustard.spreadIt’s just too good that a food writer from the L.A. Times, Noelle Carter, and Lynne Rosetto Kasper from NPR’s The Splendid Table would get together to discuss the ins and outs of making homemade mustard!! Since we are drowning in mustard seeds over here at Farm Fuel following the harvest, we are interested…

To get some real insight into the spiciness of mustard, you just have to read this interview — this is the reason our mustard meal fertilizer gets “hot” when you first water it into your soil.

What they are surmising here, from a cook’s point of view, is that the mustard you cook will have more tang if you mix it with water rather than vinegar, wine, beer, and all the other creative hydrators people have come up with in their recipes.

Another thing about these recipes is that they left out turmeric, that fabulous root from India (think ginger), which makes ballpark mustard so yellow. It’s one of the reasons mustard is healthy for you. Since most of the seed we’ve harvested has run through some dusty machinery, it’s not really food grade, but I did harvest a little by hand to give mustard making a try. Enjoy the story!

Ag Alert article describes fumigation alternatives

Strawberry growers rid soil of diseases

Ag Alert is a publication of the California Farm Bureau Federation

Issue Date: September 3, 2014

By Bob Johnson

Jonathan Winslow, farm services manager for Farm Fuel Inc. of Watsonville, checks a field of strawberries that had undergone anaerobic soil disinfestation to rid the soil of disease pathogens.
Photo/Bob Johnson

With the clock running out on the use of methyl bromide to fumigate before planting strawberries, an increasing number of growers are showing interest in a method of ridding the soil of disease pathogens without chemicals.

In anaerobic soil disinfestation, tons of rice bran are incorporated into the soil, the ground is tarped, irrigated to capacity and kept saturated for three weeks, and then holes are punched in the tarp for planting.

The California Department of Pesticide Regulation is providing grant funding to expand the commercial use of anaerobic soil disinfestation, or ASD, and University of California, Santa Cruz, researchers continue to explore the finer points of managing the system.

“Last year, people moved from one-acre trials to entire blocks,” said Jonathan Winslow, farm service manager for Farm Fuel Inc. of Watsonville. “For 2014, we’re already past last year, and we’ll probably jump up when we get to the late-year planting in the Watsonville and Salinas area. We are working to implement ASD on a commercial scale.”

Farm Fuel contracts with farmers to supply rice bran, with or without mustard meal, and monitors changes in soil oxygen, moisture and temperature.

Growers used this method to prepare 130 acres of ground for berries in 2012, then expanded to more than 430 acres in 2013. And disinfestation is attracting interest from a broader group of growers, as use in conventional berries increased from just five acres to more than 120 acres in one year.

“We’ve gotten between 85 and 110 percent of fumigant yields with nine tons of rice bran,” said Carol Shennan, UC Santa Cruz professor of environmental sciences. “We’ve gotten an 80 to 100 percent decrease in verticillium, which means you may still get the disease if you start with very high levels.”

The system works to control diseases, observers said, but it does not work with the consistency of fumigation with methyl bromide plus chloropicrin.

Winslow cautioned that growers must carefully calibrate the application rate of the rice bran, incorporate it evenly, rapidly apply the plastic mulch and completely saturate the beds.

“The first irrigation is very important. Use one inch for sandy soil and two inches for clay soil,” said Joji Muramoto, UC Santa Cruz associate researcher in the department of environmental studies. “Start irrigating and tarping soon after incorporating the carbon. Maintain water at field capacity for three weeks. The total amount of water will be three to five inches, including the first irrigation.”

Because it is particularly important to tarp and saturate the ground as soon as possible after incorporation of the rice bran, growers are finding it works best to disinfest relatively small areas at a time.

“We just do five- to eight-acre blocks at a time. There’s no way I would go 20 acres at a time,” said Manuel Mercado, who grows both conventional and organic berries near Watsonville and Salinas at River Valley Farms.

He said that ASD gives him an alternative to fumigation on ground with disease problems, particularly with verticillium wilt problems.

“The first year, we tried just one acre with the rice bran, but last year we tried 20 acres of strawberries and 15 acres of raspberries,” Mercado said. “If you have disease pressure, it’s a good tool to use. If you don’t have pressure, you have to think about the cost.”

Mercado and other growers are hoping to reduce the cost of ASD by applying rice bran at less than nine tons an acre.

“I went to six tons an acre and I saw no difference. It’s about $1,000 less per acre,” Mercado said. “It costs about $3,000 an acre for strawberries, including the plastic and the labor.”

It only costs around $1,500 an acre to disinfest ground for raspberries using this lower rate of rice straw, according to Mercado.

Rice bran, molasses, wheat bran, crop residue and ethanol have all been used somewhere as the source of carbon, according to Shennan, and researchers are looking for more economical sources.

“Skin and seed grape pomace is 20 percent cheaper, and looks comparable to rice bran,” Muramoto said. “We are also looking at summer wheat and Sudan cover crops in combination with rice bran.”

Molasses has worked as a source of carbon in other areas, but not on the Central Coast. Researchers are working to learn if half rice bran and half molasses, with split applications, can be used to supply the organic matter.

Another complication is the early season flush of nitrogen from the carbon source, which should be considered in devising fertilizer plans.

“When you add nine tons of rice bran, you’re adding 300 pounds of nitrogen, and that’s a lot,” Shennan said. “With three trials that were randomized properly, we got no yield increase from pre-plant fertilizer when we used nine tons of rice bran, but I want to see more data.”

Mercado said he waits longer to apply fertilizer for berries planted in disinfested ground, as well as adjusting the chilling hours and planting dates for these unusually vigorous strawberries.

“Because of the nitrogen, the plants take off very fast, so you have to make sure they don’t collapse later. We don’t have to apply any nitrogen until May or June,” Mercado said. “You can see an increase in organic matter in your soil analysis right away. The nitrogen also went from around 20 pounds to around 100 pounds.”

Disinfestation does little to control weeds, according to Shennan, and management of the system must be tailored to fit different diseases.

“We need to know how we can make it work for specific pathogens by manipulating the carbon source, water and temperature,” Shennan said.

In general, warmer-weather disinfestation is more effective in killing disease pathogens.

“The higher the temperature, the stronger the disease control,” Muramoto said. “Verticillium can be controlled in the early fall; once you get to November, it’s too cold for verticillium in Watsonville. For fusarium, you need to do it in August or September with clear plastic.”

Verticillium can be controlled at soil temperatures of 65 degrees Fahrenheit or higher, but fusarium control takes 86 degrees.

He recommends using ASD in combination with other practices, like crop rotation and soil monitoring.

“If you have any disease, it’s very important to diagnose what disease you have, and what pressure,” Muramoto said. “Crop rotation is also very important. We had an outbreak of fusarium in the fields at Monterey Bay Academy because we didn’t rotate.”

With all the complications and caveats, disinfestation appears to bring benefits, even under marginal conditions, researchers said.

“It seems to be a somewhat forgiving process,” Winslow said. “Even in fields with high verticillium pressure and less than ideal anaerobic conditions, disease damage is still fairly low.”

He made his remarks while standing in a field of organic strawberries producing a decent crop growing in ground outside Watsonville that was heavily infested with verticillium, and was left untarped too long after incorporation of the rice bran.

The complications and limits of ASD seem more bearable in light of the limits of the alternatives.

“As people are moving away from methyl bromide, we’re seeing more diseases, and I expect to see nematodes in the next few years. Even if the field is prepped right and you apply chloropicrin under virtually impermeable film, we still see diseases creep in,” said Mark Bolda, UC Cooperative Extension farm advisor. “This is a critical juncture for the industry as we transition from methyl bromide to the alternatives. Methyl bromide has been used in the strawberry industry for 60 years and has done a good job of controlling the pathogens and weeds. Methyl bromide is going to end for caneberries this year, and for strawberries in 2016.”

(Bob Johnson is a reporter in Santa Cruz. He may be contacted at

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