San Joaquin Valley nut industry works to cut dust

Almond and walnut growers are harvesting their crops with the help of machines somewhat like vacuum cleaners.

But unlike the household appliances, these rigs can spew out plenty of dust as they go about picking up nuts.

In recent years, industry people have worked on ways to reduce the dust, which can cause health problems for people who breathe it.

Among the innovators is Doug Flora, co-owner of Exact Harvesting Systems Co., west of Modesto. His company has made a mechanical harvester that traps much of the dust by drawing it through a big polyurethane brush. A stream of water causes the dust to form into tiny mudballs that fall harmlessly to the ground.

"Our goal all along has been to address the dust problem without compromising production," Flora said.

By that, he means that the dust-control system must not reduce the speed of the harvester. Nut growers are on a tight schedule to get the crops in before autumn storms.

Almond grower Steve Van Duyn saw a demonstration of the new harvester in his Salida-area orchard last week. He came away impressed.

"What dust there is stays really close to the machine and drifts back down," said Van Duyn, whose orchard was harvested the same day with a conventional machine that sent dust across half a dozen rows of trees.

Mechanical harvesting has helped make almonds the second-highest-grossing crop in the Northern San Joaquin Valley, after milk. The nuts brought about $935 million to growers last year, according to county crop reports.

Walnuts are a sizable business, too, bringing an estimated $290 million to north valley growers.

Each harvest starts with shaking the trees to bring the nuts to the ground, where they are shaped into windrows. They then are picked up by harvesters, in what tends to be the dustiest part of the process.

In extreme cases, the dust clouds can cause accidents on roads. Even moderate amounts can be trouble for sensitive people.

"It's a short-term thing, but on the days it's occurring, it can be a lot," said Jim Swaney, a permit serv-ices manager with the San Joaquin Valley Air Pollution Control District.

The dust particles are small enough to get deep into the lungs and even cross cell walls, air district spokesman Anthony Presto said. "You are affecting lung function, and you are also affecting the heart."

The district has worked with the almond and walnut industries on dust-control measures. They include smoothing the orchard floor before harvest, tweaking the fans and other parts on the machines, and aiming dust away from roads and homes. If time is not an issue, harvesters can slow down.

Machines in wide use today have reduced dust by 30 percent to 40 percent compared with 20 years ago, said Gabriele Ludwig, who oversees research at the Almond Board of California, based in Modesto.

Efforts on dust reduction continue, but it is unlikely a nut orchard ever will be as clean as a living room rug. Summers are long and dry in the Central Valley, and irrigation stops before harvest because the crop should not get wet.

"It's not that there won't be any dust," Ludwig said. "It's reducing the amount of dust."

Bee staff writer John Holland can be reached at jholland@modbee.com and 578-2385.