Arrow-right Camera
The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Traps, sprays help keep fruit free of pests, chemicals

These pie cherries were grown organically. (Susan Mulvihill)

Several years ago, my husband and I started growing our tree fruits organically because we wanted to avoid using chemicals.

Bill and I grow plum, cherry, apple and pear trees. Plums are a gardener’s dream because they are generally trouble-free. Cherry fruit flies, however, are the source of icky white worms. Apples and pears can be particularly challenging due to the number of pests and diseases they’re susceptible to.

I’ve written in the past about the organic methods we’ve used, but like other aspects of gardening, we are learning more every season. Here’s what we’re doing this year:

We use indicator traps to determine when our two worst pests – cherry fruit flies and apple codling moths – are in the area. Indicator traps are coated with an adhesive that insects get stuck to.

Cherry fruit flies lay their eggs in cherries once they start turning yellow. Because of this, cherry fruit fly traps are bright yellow and do a good job of attracting them. We hang the traps when the cherries become light green.

Apple codling moth traps contain pheromones that attract male moths. We put them in the orchard right after the apple blossoms drop.

Once either of the insects are active in the area, we need to spray the trees they’re attracted to.

Bill uses an organic spray containing spinosad on the cherry trees every 10 days. He sets the sprayer to shoot large droplets; the spray kills the adult flies before they can lay eggs. He’s careful to spray it early in the morning before bees and other pollinators are active, or in the evening after they’ve settled down. He avoids spraying near any flowering plants. This year, we had virtually no maggots in our cherries.

The apple trees require a slightly different approach. When the developing apples are about the size of marbles, we thin them 6 to 10 inches apart so the tree doesn’t have to support and grow too many of them.

Prior to this year, we’ve covered all of the apples with little nylon footies and sprayed the trees with kaolin clay in an effort to confuse the codling moths and make it difficult for them to lay eggs on the apples. While effective, that was tedious, and we kept wondering if it was worth the effort.

This year, we decided to skip the footies. Instead, Bill has used the kaolin spray combined with Bacillus thuringiensis (Bt) weekly during heightened codling moth activity. Bt is a strain of bacteria that is harmless to humans but deadly to worms and caterpillars. Later in the season, he only sprays when rain washes it off the foliage and apples.

It’s important to follow the directions on spray labels. One shouldn’t spray more frequently than the label suggests; otherwise, insects can develop an immunity to it.

On a regular basis, Bill and I walk through the orchard to monitor how the apples are growing. If we see any codling moth damage, we remove the apple immediately and toss it into the trash instead of the compost pile.

We anticipate about a 90 percent success rate with this year’s orchard program, which we are very satisfied with. For more information on organic orchard practices, visit my blog at susansinthegarden.blogspot.com.

Susan Mulvihill is co-author, with Pat Munts, of “Northwest Gardener’s Handbook.” Contact her at inthegarden@live.com.