The Wonder Weeder has cultivating heads that roll along the ground and eliminate vegetation. Designed to avoid tree damage, they also open up vole burrows and expose the animals to predation. The cultivating can be done at the same time as mowing and blowing the clippings into the tree row.
Mike Brownfield’s orchard has been cultivated organically for almost 40 years. In recent times, Brownfield has benefited from a number of new tools that make organic production less problematic. But there’s one aspect of organic production that remains a challenge, and that’s replanting. There is not yet an organic-approved method to overcome replant disease.
Replant disease occurs in orchards where fruit trees (apples, pears, cherries, etc.) are planted into ground where tree fruits previously grew. Though the previous trees grew normally, new trees planted into the same ground don’t grow as well and are less productive. It’s estimated that the loss in productivity can reduce the grower’s revenue by about $40,000 per acre over the life of the orchard, David Granatstein, sustainable agriculture specialist with Washington State University, reported during an International Organic Fruit Research Symposium this summer. The symposium agenda included a visit to Brownfield’s orchard.
Replant disease is caused by a complex of microorganisms that build up in the soil around the tree roots. Because the mix of organisms can vary from site to site, fumigation, which is a nonselective treatment, works well.
Dr. Mark Mazzola, plant pathologist with the U.S. Department of Agriculture in Wenatchee, Washington, has been researching alternatives to fumigation that might work in organic agriculture and has had good results with preplant treatments of seed meals of the mustards Brassica juncea, Brassica napus, and Sinapsis alba. Seed meal is what remains after oil is extracted from the seeds. However, the seed meals are not yet approved by the U.S. Environmental Protection Agency for use as pesticides.
Granatstein said, lacking an organic treatment, growers often take the blocks they intend to replant out of organic certification, then fumigate the ground and begin the transition back to organic, which takes three years. By the time the orchard begins producing a commercial crop, it should be certified.
Brownfield said that’s just what he’s done, despite the copious amount of paperwork it involved. He found fumigation made a huge difference in a block of Blondee on Malling 9 Nic 29 rootstocks now in its second leaf.
“This is the most successful block I have ever had,” he told symposium participants when they visited his orchard. He fumigated and added lots of chicken-manure-based compost, and had good quality trees to begin with.
He fumigated in the spring, which seemed to get the trees off to a better start than the fall fumigation he’s done in the past. He seeds alfalfa and clover in the alleys, which reduces the amount of compost that needs to be applied to the trees.
Brownfield, who farms about 50 acres, said growing a diversity of fruit and selling about a third of the production himself have been keys to sustaining the business. He’s not trying to get bigger, but is trying to maximize the value per acre.
His father, John, established the orchard in 1972 and began organic farming a couple of years later in an effort to find a healthier way to farm. In 1987, the farm was the first to become certified organic by the Washington State Department of Agriculture.
Brownfield grows apples, pears, cherries, peaches, nectarines, and apricots. He packs and markets about a third of the apples, 15 percent of the pears, and all of the peaches, nectarines, and apricots himself as a way to bring more dollars back to the farm. The rest are packed and sold by Stemilt Growers, Inc., in Wenatchee.
Brownfield supplies many of the retail food cooperatives in western Washington, outside the Seattle area, with apples and pears, driving over the Cascade Mountains to deliver them every week for a six-month season. He sells most of his stone fruit locally.
Brownfield has a small planting of Zestar!, which is one of the earliest maturing varieties and is popular with his customers, and has just planted another block. “People are asking, ‘Where are the Zestars?’ when I run out of them,” he said.
Jim Luby, head of the University of Minnesota’s fruit breeding program, where Zestar! was developed, happened to be on the tour. He said Zestar! is being planted in the eastern United States to a moderate extent. It is popular for direct marketing because of its exceptional flavor but is susceptible to scab, which is a problem in humid areas.
Market diversity, both in terms of varieties and types of customers, has been the key to the orchard’s economic viability, Brownfield said.
“We’re finding ways to keep going. The direct marketing is a huge part of it for us. I feel real good about the organic market right now.”
On the production side, Brownfield is benefiting from a number of revolutionary practices that have become available for organic agriculture.
Weeds can be difficult to control because synthetic herbicides are not allowed and natural herbicides are expensive and less effective. Brownfield used to use a standard in-row tiller to cultivate the soil and uproot weeds, but the risk of damaging the trees was high, particularly if the operator wasn’t well trained.
The Wonder Weeder he now uses has cultivating heads that roll along the ground, rather than being powered, which reduces the risk of damaging trees. It is attached to the front of the tractor and can be used at the same time as a mower at the rear. Brownfield has a side-discharge mower that blows the alfalfa and clover clippings into the tree row.
Brownfield said that because of the low risk of tree damage, he can use the Wonder Weeder in his younger blocks. The big advantage is that he can control weeds, mow the orchard, and apply the cover crop mulch as fertilizer all in one pass while driving at more than 6 miles per hour. The Wonder Weeder also opens up vole burrows, exposing the animals to predation by hawks. Voles used to be out of control, he said, but now he rarely loses any trees.
Years ago, he used many soil amendments, such as gypsum, phosphate, and blood meal, to get the nutrient levels he wanted in the soil. Now, he just applies a bulk compost at a rate of four to six tons per acre annually (banded in the tree rows) for young trees and one ton per acre for older blocks.
“If you can handle bulk compost, it’s the least expensive and has all the benefits,” he said.
Thinning sprays have been another big advance for organic growers, Brownfield said, as they have helped reduce labor costs and even out year-to-year production. He applies a solution of 2 percent lime sulfur and 2 percent fish oil in 100 to 125 gallons of water per acre three times during bloom, focusing on the tops of the trees. He increases the lime sulfur to 3 percent for Fuji apples.