Apple trees (Malus domestica and other species) benefit from pruning in many ways. Pruning apple trees makes them better able to support the weight of the fruit, produces higher quality fruit and makes it easier for fungicides and insecticides to penetrate the tree’s canopy. Unfortunately, many gardeners choose to prune their apple trees in the fall, which is one of the worst times to prune apples. Apples trees should be pruned in late winter or early spring for best results. Fall pruning can cause many unintended consequences and have a negative impact on tree health.
Like all plants, apple trees gather carbohydrates, nitrogen and other nutrients they need from both the soil and the photosynthesis occurring in the leaves. The tree distributes these nutrients as needed during the growing season. To conserve nutrients and store them for the next growing season, the tree moves nutrients out of the canopy and into the roots and trunk for winter storage. This allows the tree to maintain a constant energy level during winter dormancy and quickly move nutrients back into the canopy when needed for spring growth. Fall pruning interrupts this flow of nutrients, removing parts of the tree’s canopy before the nutrients have been moved elsewhere in the tree. This makes the tree work harder to create new growth in the spring, potentially reducing both yield and overall tree health.
Although beneficial to the tree in many ways, pruning a tree actually inflicts damage on it. Pruning causes a wound that the tree heals by creating new growth at the site or, in the case of very large limbs, scabbing over. Fall is a time when apple trees should be preparing for dormancy, not generating new growth that won’t have time to harden off before cold winter temperatures arrive. All of the tender new growth created by the apple tree after a fall pruning will die or suffer cold weather damage. Dead and damaged limbs will not continue to grow and develop properly and will not fruit.
The fungus, bacteria and insects that sometimes infect apple trees are all living things that seek out a place spend the cold winter months. Unfortunately, fresh cuts on an apple tree provide them with an easy entrance into the tree where they can survive the winter and have a ready food supply in the spring when the tree begins to grow again. Once established, some infections can be very difficult to treat and may alter both the quantity and quality of the fruit produced by the tree. Pruning later in the season gives the tree a chance to heal before warm weather reawakens fungus, bacteria and insects.
What Can Be Done
Although apple trees shouldn’t be pruned in the fall, there are some things that you can do to promote the health of your tree. One is to rake up any fallen leaves and fruit from under the tree and dispose of them. It is also a good idea to rake up any old mulch and replace it with new. Just as fungus and bacteria can overwinter in the apple tree, they can also hide in fallen leaves and rotten fruit that aren’t cleaned up before winter. Dead limbs can be removed from apple trees in the fall as long as you do not cut into any living wood when removing them.
- North Carolina State University: Pruning Trees
- University of Saskatchewan: Fall Care of Fruit Trees: Dont's and Do's
- Ontario Ministry of Agriculture, Food and Rural Affairs: Pruning Fruit Trees
- Virginia Cooperative Extension: Training and Pruning Apple Trees
- Rodale: Fall Pruning: Don't Do It!
- Fruit Tree Update: Don't Fall Prune Fruit Trees
- Yardener: Month to Month Tasks for Apple Trees
- Digital Vision./Digital Vision/Getty Images