Thefts of nuts are putting a dent in the $1.3 billion California walnut industry and could pose a food safety threat that could cripple the industry.

That was the warning sounded by Marilyn Kinoshita, Tulare County agricultural commissioner, at this year’s 44th Tri-County Walnut Day meeting in Visalia. Kinoshita talked of changes in a Tulare County ordinance that she hopes will become a model for other counties in the face of thefts that are both costly and potentially compromising as the federal government looks to step up food safety requirements under its Food Safety Modernization Act.

In a brief talk at the meeting, Kinoshita said the county, among the leaders in walnut production with a crop valued at about $140 million in 2011, has tightened regulations in an effort to thwart as much a couple dozen thefts in a season in that county alone. She said she believes the California Walnut Commission should make the curbing of thefts “a top priority.”

Kinoshita shared the podium with commission leaders who touted growth in the industry as it makes gains in new markets, in part due to health research; a weed control authority who recommends more use of pre-emergents rather than trying to zap weeds after they are already in the orchard; and a specialist in irrigation for developing orchards.

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Other topics including spacing of trees, codling fly and husk fly management, identification and management of canker diseases and nutrient management.

Kinoshita said eight people were prosecuted through the Tulare County District Attorney’s Office for thefts last year after changes in the ordinance that made it a crime to attempt to sell any quantity of walnuts without proof of ownership and established “buyer periods.”

She said thievery had reached such a level that growers hired security guards to patrol orchards. The stolen nuts, lifted from orchard floors, were sold at street markets or to handlers and packers. North of Tulare County, there were thefts of truckloads of nuts.

Kinoshita said the sale to handlers can be especially problematic because there is not the traceability that comes with other walnut purchases. With the federal government looking at new food safety regulations, she said, the industry could be seriously hurt if handlers co-mingle untraceable purchased nuts with others. She cited the instance of cantaloupe contamination out of Colorado that took its toll on sales of that commodity out of California and elsewhere.

Kinoshita said the Tulare County ordinance specifies that growers can pick up permits that allow gleaners to pick up nuts within an orchard. “We don’t need worm motels on the orchard floor,” she said, adding that the permits keep law enforcement from spending time on legitimate collection of nuts.

The new ordinance resulted from cooperation with the commission, with the county Department of Agriculture, the county’s District Attorney’s Office and Sheriff’s Office and the Tulare County Farm Bureau.

Industry growth

The Visalia program opened with Dennis Balint, CEO of the California Walnut Commission, and other staff members talking of how marketing order assessments have helped grow the industry to a point of doubling since 2000 as consumers have come to see the nut as a healthy source of fat.

The presentation looked at activities of both the commission, funded by assessments on growers, and the California Walnut Board, funded by assessments on handlers.

Balint said last year’s crop, projected at 470,000 tons, “finished at 497,000 tons.” He said prices for in-shell nuts in 2011 averaged $1.46 per pound. Recent foreign marketing successes include a U.S.-Korea Free Trade Agreement that is cutting tariffs on walnuts going into that country.

Kurt Hembree, a Fresno County farm adviser for the University of California, said he would like to see increased use of pre-emergent herbicides in walnut orchards, particularly given that some weeds are developing resistance to post-emergents such as glyphosate.

He said newer pre-emergents can be used to control fleabane, jungle rice, horseweed and ryegrass. Hembree also recommended rotating herbicides and using ones with variable modes of control to broaden and lengthen control and avoid development of resistance. He advises using post-emergents only “to clean up ‘escapes’ when they are small.”

Pre-emergents showing promise include Alion, Pindar and Chateau.  

Bruce Lampinen, a UC Davis specialist in walnuts and almonds, talked of light interception and pruning of walnuts. He said there is a potential for about 100 in-shell pounds per acre for each 1 percent of midday light intercepted.

Lampinen said the highest yields come from traditional spacing and minimal pruning. High density plantings, he said, are hard to manage and hedging cuts production.

Pruning can lead to the potential for limb breakage when it stops, Lampinen said. But he warned if there has been heavy pruning and it stops “there can be a disaster; I’ve seen an orchard destroyed that way.”

Allan Fulton, UC soils and water farm adviser in Tehama County, said it is important – particularly for new plantings – to avoid “missing the target” of the root zone and to use tools that include a pressure chamber, Stem Water Potential device, neutron probes, flow meters and rain gauges to assure the tree gets enough – but not too much – water.

Higher frequency and shorter irrigation sets help establish new trees. Placement of irrigation lines close to the root ball is a key, Fulton said.

Robert VanSteenwyk, Extension entomologist with UC Berkeley, said Delegate, Intrepid and Altacor are pesticides effective on different life stages of the codling moth.

He said the walnut husk fly tends to be more of a problem in climates cooler than in the Central Valley. “But last year we had tons of calls from down here,” he said, joking that perhaps “global cooling is going on.”

He said female husk flies fly high and males low, meaning that it is important to “get materials into the top of the tree.” That may mean aerial sprays, he said.

Thousand cankers

Elizabeth Fichtner, a UC farm adviser for Tulare County, gave pointers on how to distinguish between thousand cankers disease and shallow bark canker, which poses mostly a cosmetic threat. She noted that thousand cankers disease is a complex requiring both a pathogen and a pest that can carry it, the walnut twig beetle.

That disease, first reported in California in 2008, has spread in recent years, and either the complex or its carrier or pathogen have cropped up in Ohio, Pennsylvania and other Eastern and Midwestern states, which have native populations of black walnuts.

The good news for exporters of walnuts is that the pathogen and insect infest the wood, not the nut itself.

Bob Beede, UC farm adviser for Kings County, talked of nutrient needs for walnuts. He said orchards in the San Joaquin Valley often face zinc deficiencies and that foliar spraying is a good way to counter that.

He said Valley growers are facing tighter regulations on nitrates in groundwater and are being urged to join water quality coalitions and can expect that they will have to come up with nitrogen management plans.