JoAnne Skelly: May fruit tree tips

JoAnne Skelly

JoAnne Skelly

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Master Gardener Michael Janik is a fruit tree expert who advises this for fruit trees in May: “Thinning is an essential step in producing larger, tastier fruit and will also help prevent damage from insects. Cherries do not need to be thinned. Apples, pears, peaches and nectarines benefit from thinning. Plums and apricots may also be thinned if there is a heavy crop.

“Fruit should be thinned when the fruit is ¼- to ½-inch in diameter; after the fruit is an inch in diameter, it is too late to improve fruit quality by thinning. To thin, first lightly run your fingers over the fruit; a good number of the fruits will fall off as some fruits were not completely pollinated or the tree is selectively pruning itself. Then, remove any damaged/deformed fruits. Note that apples and pears form on clusters with the center fruit larger than the rest; those are the ones I leave on the tree.

“Codling moths are poised to emerge, fly, mate and lay eggs.”

Codling moths are the parents of the worms in apples and pears. The goal is to keep moth numbers low to avoid a growing population. Sanitation is the first step, so every week or so, six to eight weeks after bloom, check the developing fruit and remove any with grainy holes. Throw them away rather than composting. This gets rid of larvae before they can crawl out and begin a new generation. Also, clean up any dropped fruits for the same reason.

Be diligent. Thinning the fruit to one apple per cluster, as Michael mentioned above, is one method to reduce infestations. Banding the trunk with corrugated cardboard bands two to three inches wide in May through mid-June, then removing and destroying the bands and the hiding insects will also reduce these pests.

Bagging desirable fruit with paper bags and closing the top of the bag can help protect fruit. Native enemies alone will not protect fruit. For complete information on codling moth go to: and

“Aphid damage occurs on new growth and appears as curled, deformed leaves, especially on peaches, nectarines and cherries. If only one or two places are infected, just squash the little bugs. If the whole tree is infected, it is too late for dormant oil. Instead, attach a spray nozzle to a water hose and spray water into the affected limbs from all sides. The force of the spray will knock the aphids off the tree and onto the ground where they will cook in the noonday sun.

“Aphids are wingless in the spring and cannot return to the tree. Beneficial insects like lacewings, wasps and lady bugs will fly away unharmed and return to eat more aphids. Spraying the water in the evening every other evening for a week will bring in beneficial insects for a drink and they will stay or return in the morning to breakfast on the aphids.”

JoAnne Skelly is associate professor & extension educator emerita at University of Nevada Cooperative Extension. Reach her at


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