CORVALLIS, Ore. – People tend to have a love-hate relationship with their fruit trees. The fruit they love; the work they hate.
The regimen of spraying turns off home gardeners, said Steve Renquist, recently retired horticulturist with Oregon State University’s Extension Service. But times have changed. Research has resulted in easier methods of dealing with pests and diseases, from resistant trees to low-toxicity products. For years, OSU’s Extension horticulturists, including Renquist, have been advocating for integrated pest management or IPM, an approach using the most effective, least-toxic methods first.
“You don’t need to coach people nearly as vigorously as in the past,” Renquist said. “Everyone wants to minimize spraying. Low input means it’s better for the people eating the fruit, better for the environment in the backyard, better for the safety of the pets and family running around out there. It’s a pretty easy sell.”
When Renquist teaches classes in what he calls low-input gardening, he starts by recommending that home gardeners choose the most disease- and pest-resistant varieties. Extension Master Gardeners can recommend relevant trees, as can nurseries with expertise in fruit trees.
If you start from that point, you’ve got a much better chance of having a low-input orchard,” he said. “You don’t have to be constantly spraying for something.”
Apples and pears are the two most common fruit trees grown in Oregon because they can be grown throughout most of the state. But everyone seems to want to grow cherries, even though they’re not the easiest choice.
“Everybody has the desire to grow cherries,” Renquist said, “but after you try to grow them and keep the birds away, you realize you’re putting a lot of effort into feeding the birds. And they get a number of diseases, too, which compounds it. One of the real tortures of home gardeners is wanting to grow cherries.”
So, he advises sticking to apples, pears, plums and, if you’re in the right areas, stone fruits such as peaches and nectarines. If you’re partial to figs and persimmons, by all means plant them; those fruits are almost entirely carefree.
After choosing an appropriate variety, the next step is to be vigilant about monitoring for insect pests – like the ubiquitous coddling moth – with pheromone traps, which can be purchased from farm stores or online. Pheromone traps are also used for peach tree borer in peaches, nectarines and apricots, and filbert worm in hazelnuts. The tent-shaped traps have bases smeared with a sticky substance. On the trap bottom, place a lure with pheromones that waft a scent to attract certain insects. Starting in late spring, hang the traps in the trees and check each week. If there are more than the target level of insects caught in the trap in one week, spraying with the least toxic spray is recommended. If not, knock off the ones trapped and start counting again in the new week.
“Scientists make it pretty simple,” Renquist said. “That’s the beauty of the system. They determine the number of insects to look for. It’s something hard and fast you can follow; you don’t have to extrapolate. You’re applying on the basis of need rather than the basis of prevention.”
On top of that, the recommendations for sprays are for low-impact sprays, many of them organic, though Renquist points out that even some organic products have risks. A good reference for disease and pest control is Extension’s Managing Diseases and Insects in Home Orchards, which has a list of cultural practices and least toxic products for various pests and diseases. For information on specific products on the list contact your local master gardeners.
Renquist stresses that home gardeners need to rotate sprays – three per season is best – to avoid resistance. For instance, if your apple, pear or plum tree has coddling moth, he recommends Cyd-X, a virus that is non-toxic to anything but the moth; the organic form of spinosad; and Surround, which is a kaolin clay compound that irritates the moths and keeps them away.
Another strategy, Renquist said is to apply low-input dormant oils during the dormant season before trees have budded out. The oils smother the eggs and larvae of many insects and decrease problems down the line. Of course, keeping your trees in top shape is key.
“A lot of it is the health of the tree,” he said. “Well-timed sprays, good pruning, good fertilization. You really can have fruit produced with far fewer inputs than people lead you to believe.”