In the Garden | The enemy of my garden enemy

Tim Smith

In a recent column, I went on a rant about apricots. I braced myself for a public outcry, led by the Apricot Protection League, but, not a peep came my way. This has encouraged me to move forward into my new topic — tree fruit you won’t regret growing: peaches and nectarines.

Few gardening experiences can match the pleasure of the taste sensation of that first summertime bite into a tree-ripened nectarine. The peachy, sweet-tart flavor comes with juice that forces you to bend forward to avoid making a mess of yourself. This all comes with peaches being the easiest tree to grow, with a short wait until first fruit. It's typically a three-, four-year wait at the most.

The trees are more compact than other fruit trees. Usually, you can keep them about 12-feet tall and 16-feet across at maturity. Many people take advantage of this low-maintenance crop by sticking a peach tree in their backyard. Then they move, leaving the tree for you to use. We get a lot of peach problems brought into the master gardener clinics, so what follows are a few basic tips about their management.

First, they are short lived trees. Fifteen or 20 years is old for a peach. Replant when most of the green growth is out on the end of old, corky wood.

They need a higher level of mineral nutrition than other fruit trees. Too little, and they don’t produce the new wood that produces next year’s flowers and fruit; too much, and your fruit will be lower quality.

They need to be pruned severely every winter, or else. The fruit is produced on the shoots that grew the prior summer, so leave too much wood on the tree and you will get too much fruit set. This will cost you a lot of time thinning little green fruit. Thinning fruit early, starting at bloom time, is very necessary. Too much fruit on the tree will reduce the growth and cost you crop quality. Thin fruit to about 5-6 inches apart; they will be much better if not crowded on the bearing wood.

There are fewer pest problems with peaches than most fruit trees, and most can be controlled with organically acceptable sprays. Two fungus diseases and two insects are key pests we see most in Master Gardener clinics. The two fungus diseases — peach leaf curl and Coryneum twig blight (shot hole) — require control treatments in the fall.

I won’t tell you what to spray to control these because I’m not allowed to do that in this sort of column, but I will tell you the timing, which is now!

Peach leaf curl has become much more common in the past few years. Our dry climate prevents infection most years, but untimely rain on March 13 and 22, triggered it in 2018. This timing was critical because the leaf curl spores that live on the tree surface were washed by the rain into the opening buds on the peaches. Without the rain, no infection. Once the spores are washed into the buds, they infect the new, developing leaves. This infection turns into the thick, twisted, discolored leaves you see after bloom.

If you spray in the fall, you can greatly reduce this disease. Or, you can also spray in early to mid-March, but most people are not thinking about spraying then. The same sprays will help control the Coryneum twig blight. Come into the office at 400 Washington St. in Wenatchee to pick up a spray guide to learn what you need to spray and when you need to spray it.

A WSU Master Gardeners of Chelan County column appears weekly in The Wenatchee World. Tim Smith is one of four columnists featured.