The importance of dormant sprays for backyard fruit trees
By Bonnie Orr
WSU Chelan/Douglas County Master Gardener
Fruit trees are dormant. So are all the diseases and insects that prey on the fruit trees. The trees and insects will come to life when both the hours of light and the ground temperature are appropriate. It is not too early to plan which organic or conventional sprays you will decide to apply to curb the pests.
There is nothing as disappointing as seeing red “pimples” on the apricots, misshapen or rot in the middle of a beautiful peach, or picking stunted plums. The very worst is finding a worm in a cherry or apple!
This damage can be eliminated by appropriately applying dormant and delayed dormant sprays that will control insect pests and diseases such as overwintering scales, aphids and mites. These oil-based sprays smother overwintering fungal spores, bacterial blights, insects, larvae and eggs. The insects cause leaf damage, such as leaf curl, and leave unsightly and misshapen fruit.
Groundhog Day indicates we are halfway through winter. Dormant sprays are applied to a bare tree before the buds show any activity. This is usually in late winter when the days are in the 40s and the nights are above freezing. The right day to spray will vary depending on where you live in North Central Washington.
Delayed dormant sprays are applied a few weeks later just as the buds begin to show the first green tissue when the daytime temperature is between 45 and 55 and no freezing at night. Dormant pruning should be completed before you apply spray material so it is easier to see what you need to spray and so you don’t waste the spray.
You can treat your trees with conventional or organic material. The WSU Master Gardeners have spray schedules with suggested spray materials. You can request a spray schedule by emailing askamastergardener@chelandouglasmg.org. Provide a phone number in the email so we can contact you and answer your questions.
Pre-bloom sprays control hatching insect pests such as aphids, stink bugs, scale, peach twig borer, pear psylla, various feeding caterpillars and diseases such as peach leaf curl, coryneum blight, brown rot and powdery mildew. Whew! That is quite a list, isn’t it? You can see why these spray applications are necessary.
If you were not aware of all the problems associated with growing back yard fruit, you may want to decide not to have back yard fruit trees. Yes, the shade is nice. No, the insects and diseases are not. Lovely fruit is delicious but not rotting, marred fruit!
Since this column is discussing protecting fruit trees from pests, I think I will remind readers of the other required sprays for cherries and apples. Apples and cherries and pears are major agricultural crops in this area. An untreated back yard tree can damage the fruit in a commercial orchard. People often say, “There are no orchards near me, so I don’t have to worry.” But insects can fly or be blown by the wind for miles. Responsible backyard fruit growers hang pheromone traps to monitor for codling moths and cherry fruit flies.
Often fruit trees have grown so large that they cannot be sprayed with a hose-end sprayer. In that case, commercial spraying is the option. The other option is to treat the tree with a chainsaw at the base. Really, isn’t 200 pounds of plums on a backyard tree a nuisance to deal with?
It is never too early in the year to think about gardening.
A WSU Chelan and Douglas County Master Gardener column appears weekly in The Wenatchee World. To learn more about your local Master Gardener program, visit bit.ly/MGchelandouglas or call (509) 667-6540.