An insectary can attract bees and other beneficial insects to the orchard.
Mike Omeg checks for beneficial insects in goldenrod plants in an insectary alongside a Regina cherry block. He's watched by (from left) Drew Merritt and Kristin Currin of Humble Roots Farm & Nursery at Mosier, Oregon, and Gwendolyn Ellen of Oregon State
Oregon cherry grower Mike Omeg is worried about whether he'll have enough bees to pollinate his 370 acres of orchard in the future.
With beekeepers reporting losses of up to 30 percent of their honeybees in recent years because of colony collapse disorder, he's concerned about the availability and viability of the colonies as well as the cost. Last year, he spent $36,000 just to rent hives.
Those are among the reasons that Omeg is working to build up a resident population of native bees at his Copper Block orchards at The Dalles, which is surrounded by former rangeland. In 2007, he planted a 30-foot long insectary alongside a Regina cherry block. The six-foot-wide strip was planted with two rows of blanket flower, goldenrod, and penstemon to provide pollen and nectar for bees and other beneficial insects.
The orchard is surrounded by hills with balsam root, buckwheat, and vetch, so Omeg chose late-blooming plants for his insectary to provide a refuge for insects as the surrounding vegetation dries up in the summer.
Regina is a cherry variety that typically has poor fruit set, even when it blooms prolifically. Omeg said it blooms relatively late when few other cherry varieties are in bloom, and he hoped to improve pollination by increasing the number of bees. Since he planted the insectary, the trees have consistently set a very good crop. "I think it's in part because we have a higher population of native pollinators present because of the insectary providing them resources through the dry parts of the year," he said. "But I haven't done any scientific work to check it out."
Omeg's original motivation for attracting insects into his orchard, however, was to improve biological control of the black cherry aphid, which was a problem near harvest. He had been treating them with the insecticide imidacloprid but felt it was disrupting natural enemies of leafminers late in the summer.
Dandelions provide pollen and nectar for beneficial insects in the spring, but anything growing in the alley is soon knocked down by mowing and tractor work. He considered planting flowers in the tree rows, but feared they would interfere with water distribution from the microsprinklers.
He decided instead to put plants in containers between the tree rows. After checking the cost of various containers, he settled on lined brine-cherry bins and planted catmint in them. Catmint stays green in the heat of summer after most other plants have turned brown.
For his insectary, Omeg likes the blanket flower because it's cheap, it doesn't need much water, it reseeds itself, and it's proven attractive to several types of bees. It blooms from June until heavy frost. The only problem is that gophers like it, too. He used wood chips as a mulch on top of weedmat, which worked well for conserving moisture and keeping the weeds down, but provided habitat for the hungry gophers. The insectary is irrigated with microsprinklers from two hoses running the length of the plot.
While conservationists would like to see such plots planted with a wide range of native plants, Omeg said a commercial grower needs something that's simple to plant and manage. "As a farmer, a laundry list of plants overwhelms me," he said, noting that obscure plants can be expensive and difficult to find.
It's important to manage weeds—both before and after planting—as many dormant weeds will spring to life once the ground is irrigated, Omeg said. His weeding crew needs to be able to tell the flowers from the weeds, and it's easier to coach them when there are just a few species of flowers in the plot. "The simpler and more efficient I can make it, the less expensive it is," he explained.
The simplest and cheapest way of all would be to just water the adjoining hillside a couple of times and see what grows. Omeg did that and was astonished by the thick stand of vetch that grew.
"If I wanted to do something on the cheap, that would be the way to do it," he said. "But I actually don't want to have vetch around this orchard because it's a plant that builds up high populations of field voles that girdle our trees in winter."
Omeg is preparing to plant another one-acre piece of rocky ground adjoining his orchard with plants and grasses that are attractive to beneficial insects and butterflies as a commercial-scale insectary experiment. He told a group of conservationists of his plans to plant several islands of flowers surrounded by grasses when they visited the orchard this spring.
The land has been tilled and will be treated with Roundup (glyphosate) to control broadleaf weeds. He planned to sow summer wheat, to prevent soil erosion, and then mow it down and till the land again in the fall. He will then plant summer wheat with native bunch grasses, which are slow to become established. The wheat will be killed off during the winter, and the grasses should grow in the spring. The rationale for planting the grass before the flowers is to allow one more season when he can spray a broadleaf herbicide to control perennial weeds, such as bindweed. Spraying is the only way to control bindweed because pulling it only makes it worse, he said.
The 20-foot-diameter irrigated islands will contain six or seven flowering plants, including native wild tarragon, which is a host of the Oregon swallowtail butterfly, and narrowleaf milkweed, a host of the monarch butterfly. Omeg said that by designing the planting to benefit butterflies, he qualified for a federal grant to help establish the insectary.
"I really do believe that increasing biodiversity is an important responsibility that myself and my family have as stewards of this land, and as farmers," he said. "This doesn't take away from our orchard production, but it does take time, and money, and resources to get going."
Omeg said the ground where he's planting the new insectary is marginal for fruit production. "But if we can manage it in a way that's conducive to pollinators, natural enemies, and butterflies, we're going to be bringing in more birds and a wide variety of wildlife. The only thing I don't want is deer.
"This is an experiment that will benefit the Oregon swallowtail butterfly and also benefit the greater body of knowledge for tree fruits in how we can get something like this going," he said.