One of the most important steps in home orchard care is making dormant sprays to control overwintering insect pests, and tree fruit diseases. Dormant sprays with orchard crops are generally applied from about 50% leaf fall in November to bud break in late February, depending on the type of fruit trees you are raising.
If you are raising stone fruit crops (apricot, peach, plum, prune, nectarine, cherry) you will want to start your dormant spray schedule with an application of copper in fall when trees have dropped about half of their leaves.
The timing of these early dormant sprays will depend on the weather. If the weather pattern is like this present season, with plenty of dry, mild days, look for a two to three day dry spell before spraying, so the tree surface will be very receptive to the spray material. If you add a sticker spreader to the spray it will hold tight to the bark surface.
Copper materials have many different brand names, so just follow the label closely on the product your garden store sells. Copper is used to control diseases like shot hole fungus, peach leaf curl or Anthracnose cankers.
The stone fruit trees will also require a dormant oil spray in January or February before bud break to help control overwintering insects and insect eggs, and the final dormant spray for stone fruit trees should be sulfur at delayed dormant when the buds of the trees begin to swell.
Don’t wait until the buds are open since many fungi can enter the buds in late winter and infect the tiny new leaves. This late spray timing is critical to control peach leaf curl.
If you are raising pome fruit or nut trees (apple, pear, hazelnut, walnut) you should inspect your trees for Anthracnose canker or other cankers caused by wood rotting fungi in late fall and prune out any infected wood. After pruning out cankers, start your dormant spray schedule with an application of copper to control any canker disease spore release.
In January or February apply a dormant oil spray to control pear psylla, scale, mite eggs and aphids. This is a good organic pest control product. You can add an insecticide like Sevin to the dormant oil to improve the effectiveness for nonorganic programs.
Pear, apple, and nut trees will benefit from a delayed dormant, late winter sulfur spray before bud break, to control fungal disease, moss, and lichen especially on old fruit trees. Remember to always follow the labels of all your spray products closely.
During the fall and early winter, it is very helpful to your overall pest control program to encourage the decomposition of old fruit and leaves still in the orchard by mowing debris. Adding a small amount of nitrogen fertilizer like urea or sulfate of ammonia around your fruit trees at that time will enhance the decomposition of leaves and old fruit. This will limit disease spore dispersal and insect survival in the coming season.
OSU Extension has a helpful publication called “Managing Disease and Insects in Home Orchards” (EC 631). Access the publication online at www.extension.oregonstate.edu/catalog; click on gardening and then tree fruit and nuts. Then enter EC 631 in the search box. The publication has spray schedules for apple, pear, stone fruit, hazelnut and walnut trees.
Visit the OSU Master Gardener clinic to discuss these issues in greater depth if needed.