Courtesy Meredith Seaver, USU Extension

We get most of our pruning questions at this time of year. When should I prune my fruit trees? Is it too early to prune my roses? What about dormant oil? Does it really matter?

Fruit tree pruning

There isn’t a set date for pruning a home orchard. The kind of fruit you’re growing, where your orchard is in the valley and the late winter and early spring weather each year will help you decide when to prune. In general, late January into February is the time to begin pruning apple trees and then pear trees. Stone fruits are usually pruned a little later, starting in mid-March and finishing up by mid-April.

Very young fruit trees still need some training, and training pruning is different than the annual pruning established fruit trees receive. Focus on good scaffold branch structure for new fruit trees, not fruit production. Give mature trees their annual production pruning. You’ll find publications and videos about pruning fruit trees at different stages of maturity by searching on our website, extension.usu.edu.

The bacteria, fungi and pests that cause or spread disease aren’t active in the winter, so disease from late winter pruning isn’t usually a concern. There is sometimes a good reason to wait, though. Pruning can reduce the cold hardiness of your fruit tree for a couple of weeks, so before you prune, check the weather forecast and avoid pruning if extremely cold weather is in the 10- to 14-day forecast.

Waiting until spring will also give you milder weather and a more comfortable pruning session. You’ll also be more methodical and less likely to take shortcuts if you aren’t trying to work in freezing weather.

Is it time to prune my roses?

Courtesy Meredith Seaver, USU Extension

Timing depends on where you’re located in Utah Valley. Roses are usually pruned beginning in late February through early March when we can expect to be having milder weather. Keep an eye on the weather forecast for your area, watch for steady overnight lows that are no longer in the teens and twenties, and then get that pruning done!

Is it time yet to spray dormant oil?

Horticultural oil sprays are an important part of a good pest management program. An oil spray applied at the right time can suffocate overwintering insects, eggs and mites, reducing the number of pests you’ll have to deal with during the growing season. This also helps to protect beneficial insects in your landscape by reducing the chemical sprays that might be needed during the growing season.

The right timing for your oil spray will depend on what pest you need to control There are a few pests that should be managed with a dormant oil spray in early spring, but for most pests you’ll want to delay your oil spray until some point between the time buds begin to swell and the time when the tips of leaves just start to show. This delayed-dormant oil spray will catch pests as they hatch or emerge from overwintering sites and out onto the tree. The exact timing of a delayed dormant spray will vary depending on the kind of tree and on the location of the tree.

The oil you use should be a horticultural oil specifically formulated for use on plants. It is usually a petroleum- or vegetable-based oil. For dormant and delayed-dormant sprays, the oil should be diluted to a 1.5% to 2% solution. If you need to use an oil spray to control mites or aphids during the growing season while leaves are on your trees, you should dilute the oil to 1% or less so you don’t damage your trees.

For the most up-to-date information about timing your dormant oil sprays and other pest management spraying and control methods, subscribe to our free email advisories at https://pestadvisories.usu.edu/subscribe/.