Unprecedented Losses Plague Lettuce Growers As Salinas Valley Scrambles To Contain Pests That Threaten The Region’s Biggest Crop


By the time the good news about lettuce was announced, some of the bad news had already arrived, and a lot more was on the way.

In June, the annual crop report for Monterey County was released and it showed that the industry’s revenues from lettuce were way up. The leafy greens that allow Salinas Valley to call itself the “Salad Bowl of the World” generated $1.36 billion in sales in 2019, more than any other crop. Leaf lettuce was up nearly 15 percent from the previous year, and head lettuce was up about 12 percent.

It was hard to celebrate, however, because the coronavirus had been ravishing the industry for months. With demand for lettuce from restaurants plummeting, farmers almost immediately reported they had lost or declined to plant more than 2,000 acres in the Salinas Valley. Economists were projecting that California agriculture would shrink by $8.6 billion. Thousands of farmworkers were losing their jobs. Those who did work saw Covid-19 infect them at the highest rate of virtually any profession.

Deemed essential and expected to keep operating, agriculture was, and remains, a prime target for the coronavirus. As the impending arrival of a vaccine brings hope to the industry, however, another far more obscure virus threatens Monterey County’s top crop.

There almost seems to be a microbial conspiracy afoot. A virus spread by tiny flying insects is turning leaves brown, dry and dead. A mold that produces spores that swim through well-irrigated soil to target lettuce roots is causing them to rot until the plant can no longer feed itself. A bacteria coming from who-knows-where is clinging to the lettuce as it’s harvested, processed and shipped, and sometimes sickening salad eaters thousands of miles away.

“The losses were devastating in individual fields, in the range of 40 to 100 percent,” Richard Smith, a University of California farm adviser for Monterey County, says of crop loss this fall. “It was significant enough to cause a shortage of lettuce in September and October.”

Indeed, fast-food chains in some parts of the country were telling customers no lettuce was available for their burgers and sandwiches.

“We have not seen two diseases cause such extensive losses in the past,” Smith says, referring to the work of the virus, Impatiens necrotic spot virus, or INSV, and of the water mold Pythium uncinulatum.

Meanwhile, concern about a pesky strain of the bacteria Escherichia coli, or E. coli, led Canada to impose severe import limits on romaine from the Salinas Valley.

“There seems to be one thing after another,” Monterey County Agricultural Commissioner Henry Gonzales says. “These problems only add to the woes we have with Covid and the fires.”

But, Gonzales adds, lettuce has always followed boom and bust cycles. “In some years, some growers will not make a dime from lettuce but they will continue growing it because when the market is good, you make up for the bad years.”

He remains bullish: “I would say pay attention to the challenges, but I wouldn’t lose sleep over it because one of the things that gives us our strength is the diversity of crops that we grow in Monterey County.”

That confidence about the resiliency of local farming might prove true, but it is facing a historic test.

Monterey County Agricultural Commissioner Henry Gonzales is projecting confidence in the face of multiple attacks on Salinas Valley lettuce. He says our farmers have overcome adversity before and that region’s economy is stronger than any single crop, even lettuce, the number-one crop in the county’s biggest industry. When he released the 2019 crop report, Gonzales praised the “exceptional diversification” of Monterey County’s crops.

MARK MASON IS A VETERAN OF SALINAS VALLEY FARMING, having worked in pest control and crop management for decades. “I am a field guy,” says the Huntington Farms manager. During the growing season, he says he spends 99 percent of his time on the job outdoors making sure the crops grow according to plan.

He was among the first to realize the extent of the trouble facing lettuce. The losses that were coming would not register in the coming crop report but they were already visible in the field last year.

“The ‘oh, shit’ moment came at the end of last year with INSV,” he says. “I could see the virus coming into the edge of the lettuce field, and the edge kept getting bigger and bigger.”

“We are the Salad Bowl of the World and this thing is kicking our ass.”

He thought he could control the spread by killing bugs that carried the virus, which are known as thrips. So he had his crews spray for thrips. The virus kept spreading, so they sprayed again. Nothing. At that point, he rang up an entomologist. “I can’t control these thrips,” Mason told the insect expert. “We have got a problem here.”

The entomologist, Alejandro Del Pozo-Valdivia from the University of California’s Agriculture and Natural Resources, who has since left for a job in Virginia, teamed up with Daniel Hasegawa, an insect researcher from the U.S. Department of Agriculture, to study the problem. They realized that even in the absence of lettuce after harvest, the virus remained. “They started finding the virus in the weeds,” Mason says. “It was overwintering in these weed hosts.”

The threat of INSV is not new. The virus has been damaging California lettuce since 2006, but never on the scale of this year. Industry and government officials created a task force to search for answers.

“We are trying to figure out why we got hit so hard this year,” Mason says. “And is it going to be bad next year? We are looking at pesticides, crop rotations, biological treatments, seed treatments – anything we can do to mitigate this problem.”

For most of December, lettuce planting is on hiatus – a restriction imposed by a county ordinance. The annual December pause was enacted as a response to a flare-up of a different pest, the lettuce mosaic virus. What worked for that virus won’t work for INSV, because INSV can easily hide out in the weeds and hop back onto the lettuce when it grows anew. But the pause in lettuce growing does create a window of opportunity. The INSV task force is hoping to take advantage of this time to control the weeds that help the virus survive. “It’s the weakest link so you have to try to break the cycle before the next season,” Mason says.

The list of species of weeds that act as hosts is long: malva, short pod mustard, sow thistle, lambsquarters, shepherd’s purse, nettleleaf goosefoot, marestail, nettle, field bindweed, purslane, flax leaf fleabane and the nightshades.

Eliminating all of them is a massive challenge, says Gonzales, the ag commissioner.

“Most of the growers do a really good job keeping their fields free from these weeds,” he says. “Other entities aren’t perhaps as keen about controlling them. The counties, the cities, the state and the railroads – all of them have right of way in these areas. They do control their weeds to a certain extent but not necessarily to the degree we need them to. We are trying to get encroachment permits from the railroad and Caltrans to go on their properties and control these weeds for them.”

Professor JP Dundore-Arias runs the new plant pathology lab at CSU Monterey Bay, where he employs students as research assists. Karla Jasso, pictured above, has painstakingly gathered in vials more than 100 isolates of the pythium pathogen that’s attacking lettuce. She’s contributing to real work while gaining experience for her career.Parker Seibold

LAST YEAR, AS CSU MONTEREY BAY WAS PREPARING TO INTRODUCE ITS FIRST AGRICULTURE-FOCUSED DEGREE PROGRAM, it hired JP Dundore-Arias, a plant pathologist trained at the University of Wisconsin-Madison. The new job was an opportunity to deepen the university’s relationship with the Salinas Valley. He looked forward to educating a student body that included people with a similar background to his own. A native Spanish speaker, Dundore-Arias was raised in Costa Rica and studied English as a second language in order to advance academically.

In addition to teaching, Dundore-Arias would use his faculty position to embark on a research project in his field. He decided to study a little-known disease called pythium wilt. It was caused by a mold that is known to inhabit water-logged soil.

Pythium was first detected in the Salinas Valley in 2011. “But it was never a major issue,” Dundore-Arias says. “Some yield losses were reported but nothing dramatic or devastating.”

The best reason he had to pick pythium was that no one else was working on it. “It was like an orphan pathogen,” he says. “I didn’t know it was going to be the mess that it turned out to be.”

Pythium produces two types of spores. Two-tailed zoospores swim through soil that is saturated with water until they find lettuce root tissue. Oospores are sexual and responsible for pythium’s reproduction. They are round with spikes and “look a little like Covid-19,” Dundore-Arias says. Due to the thick walls enclosing them, oospores can survive in the soil for years.

In the spring of this year, Dundore-Arias and his student researchers were out in the field collecting samples across the valley. Their work was being funded by the industry through a grant from the California Leafy Greens Research Board. They would yank out wilted lettuce – “It feels like pulling a dead body out of the ground,” Dundore-Arias says – to look for characteristic signs of pythium: roots that are decaying and have turned from yellowish to brown. “Pythium rots the roots. The plants are stunted. The leaves become wilted because the roots can’t feed them,” he says. They would mark locations on the map and take the samples back to the lab to confirm the diagnosis.

When the researchers returned to the fields in the fall, pythium seemed to be everywhere, especially around Gonzales and Chualar, but also as far north as Castroville and as far south as King City. “The level of infection we saw in the fall was many times greater than in the spring,” Dundore-Arias says. The disease seemed to be more severe for certain varieties, such as romaine, and less so with red leaf lettuce. Photographs he took show entire crop rows decimated. “We saw a 100-percent loss in some fields,” he says.

Becoming the pythium guy during a pythium crisis meant that unnerved farmers swarmed him with calls for help. “Because this is a new disease, there is a lot of desperation and a lot of requests for answers, but we just don’t know yet,” he says. “This is a very under-studied pathogen.”

The working theory is that this fall’s devastating spikes have to do with the heat waves that hit the Salinas Valley in August and September. When it gets very hot, the natural instinct of a farmer is to water more to make sure the soil has enough moisture. But wet soil facilitates the transmissions of pythium; its zoospores can swim quickly through the mud. When pythium hits and the roots of the lettuce stop drinking, the water accumulates in the soil, making the field more hospitable for the pathogen in a self-reinforcing cycle. This theory is corroborated by the burst of phone calls to Dundore-Arias arriving almost exactly two weeks after each heatwave.

“Between this disease and INSV, I have heard a lot of farmers saying they are very close to just walking away from planting more lettuce,” Dundore-Arias says. “They cannot just keep losing money at that magnitude.”

Mason, of Huntington Farms, has heard the same sentiment: “I only have second-hand info on this, but some growers are talking about not growing lettuce in this region anymore, which is really unheard of. We want lettuce grown in Monterey County. We don’t want to lose that revenue and those jobs.”

The full extent of the losses won’t be clear for a while. Certainly not until after the ag commissioner’s office sends out its annual survey for growers. Their answers will be collected, tabulated, and then published in the aggregate sometime in the middle of next year when the crop report for 2020 comes out.

IF INSV AND PYTHIUM ARE A MENACE ON THE SUPPLY SIDE OF THE LETTUCE BUSINESS, there’s also a threat on the demand side. In early October, in a move that caught local growers by surprise, Canadian food safety officials announced restrictions on the import of romaine lettuce grown in the Salinas Valley.

The announcement cited an investigation into recent years’ outbreaks of E. coli that were traced back to lettuce grown on the Central Coast of California. According to the new rules, local romaine would have to undergo costly testing before it is allowed into Canada. The country is a major trading partner for Monterey County.

The Canadian announcement was not received well. Jimmy Panetta, D-Carmel Valley, the U.S. congressmember representing the region, called the romaine rule an “unwelcome surprise” and “burdensome to the Central Coast agriculture industry and will likely fail to improve the overall safety of romaine lettuce.” He questioned whether Canada’s food safety agency was basing its decision on sound science.

“We are trying to figure out why we got hit so hard this year. And is it going to be bad next year?”

From the growers’ perspective, the Canadians were ignoring all their efforts to prevent new contaminations.

By the end of the following month, it became harder to argue against the Canadian decision. A state lab in Michigan had detected E. coli during a routine sampling of a product packaged by the Salinas Valley’s Tanimura & Antle. The company announced a voluntary recall. Eleven days later, Fresh Express said it was recalling an expired salad kit because of potential contamination. Then, Dole Fresh Vegetables recalled organic romaine hearts from the Salinas Valley. In all three cases, no illnesses were reported, and the companies said they were simply being extra cautious.

“Canada is trying to project itself and it has implemented restrictions that are going to make it hard for us to stay in that market,” Gonzales says. “I don’t know what they are going to do to get lettuce.”

The U.S. government and farm groups are in talks with Canada. They are trying to convince officials to stop targeting Salinas Valley lettuce, according to Gonzales. “We are probably the best in the world at growing lettuce,” he says. “We have experience and the climate.”

One explanation he offers for the spike in outbreaks is that our systems for detecting contamination and identifying the causes of illnesses have improved. “We are more aware of when people become sick,” he says. “The [U.S. Centers for Disease Control] have a better system for capturing this. Before, these things were likely happening and we were not aware of it. The question becomes, what do we do about it?”

JP Dundore-Arias joined CSU Monterey Bay as a professor of plant pathology last year soon before the onslaught of pythium wilt. “This disease occurs late in the season when the plants are ready for harvest,” he says. “The farmer has money into labor, fertilizer, everything – and then in 10 days their whole field is gone.”Parker Seibold

GONZALES’ QUESTION IS ONE THAT FARMERS OFTEN CONFRONT AS PROBLEMS POP UP IN THE FIELD. There’s a state-run system in place that’s supposed to search for answers and provide relief, but many in the Salinas Valley say that system is not functioning well anymore.

Farm advisers working for the University of California’s Agricultural and Natural Resources arm and specializing in different areas are supposed to be available when the industry needs help with pests, irrigation, weeds or anything else. This program has a local office in Salinas and it is known as Cooperative Extension Monterey County.

“Whenever a grower has an issue, such as ‘I can’t kill a bug’ or ‘my nitrogen is being leeched,’ the farm advisers are like 911,” says Mason of Huntington Farms. “They are an unbiased research group. The farm adviser comes out and he asks 85 questions and starts pinpointing the problem and coming up with solutions.”

When the pythium outbreaks happened, farmers should have been able to turn to a UC farm adviser specializing in plant pathology. Or the farm adviser should have already been working on the issue.

But that position and others have remained vacant as the program’s budget has been cut, says Jennifer Clarke, the executive director of California Leafy Greens Research Board. “They truly don’t have the money,” she says. “They have never recouped from the cut in 2008, and they took another big cut this year with Covid.”

This year, the UC cut 12.7 percent from the UC Cooperative Extension program. Across the entire system, there are about 180 farm advisers and specialists. That’s down from more than 500 in 1990, according to Clarke. Right now, six advisers serve Monterey County. An annual report from 2006 lists 13 serving the county.

Clarke has been advocating to restore funding for farm advisers: “Farm advisers were so helpful to me early in my career – they are hugely important,” she says.

The designated plant pathologist left a few years ago so another UC farm adviser, Richard Smith, has stepped in to help with the virus and the mold – but his expertise is in weed science.

By a fortunate coincidence, CSUMB had just started an ag program and hired Dundore-Arias and Professor Elizabeth Mosqueda. “Both JP and Elizabeth have been great assets to the ag community,” Clarke says, but they are not a replacement for full-time farm advisers. “They are both constrained by their teaching responsibilities.”

The same goes for Hasegawa, who works for the USDA ag research station in Salinas. In the absence of a UC entomologist, he helps with insect issues but he can’t be available all of the time.

“We are the Salad Bowl of the World and this thing is kicking our ass and we don’t have farm advisers,” Mason says. The group of experts that’s been assembled is great, he says, but it’s not enough. “We are behind the eight ball. This is blowing up in our faces. It’s actually embarrassing.”

By Monterey County Weekly