Pruning your young fruit tree
By Andrew Land
Although we always suggest giving our shade trees a few years to get established before first touching them with pruners or a saw (other than to remove dead/dying/damaged limbs), fruit trees are a slightly different beast. The primary difference is that fruit trees can have literally hundreds of pounds of fruit hanging from their branches once they mature, meaning the importance of strong architecture is far more significant. Furthermore, fruit trees need sunlight for fruit to ripen and good air circulation to prevent fungal diseases, the latter being of particular importance in a climate like ours. Pruning can improve conditions on both fronts and can be started the year your fruit tree is planted.
Before making any cuts at all, it will help to understand the very basics of tree biology and architecture. First off, branches growing upright will put their energy into growth, whereas branches growing closer to horizontal relative to the trunk (parallel to the ground below) will put their energy into producing fruit.
This may make you think you want to leave nothing but branches that start as growing perpendicular to the trunk, but there’s more to know. As little fruits start to form along a branch, that branch will droop more, so you should select five or so lateral side branches to grow from the trunk that are growing somewhere between 45 and 60-degrees relative to the trunk before the fruits have formed. An angle more acute than 45-degrees can result in what’s called included bark, which is exactly where branches normally break on fruit trees if not addressed early.
Furthermore, when choosing which lateral branches (growing from the trunk) you want to leave, not only is the angle important but also the direction they’re facing. If you’re looking straight down the trunk of the tree from above, you want the lateral branches to look like five or so spokes of a wheel spiraling outward in opposing directions. That will make it easier to harvest, give the canopy of the tree better balance around the trunk, ensure that no branch is growing directly above another and shading the fruit that need sun to ripen, and allow water and minerals to flow up from roots via the xylem. On that last point, if one branch is directly below another on the trunk, it will “steal” water and nutrients from any branches directly above it as the other casts shade on it, which we can easily prevent through spiraling.
To get started pruning your newly-planted fruit tree, the essential tool for pruning a young fruit tree is a pair of sharp hand pruners. You should be certain to use “bypass” and not “anvil” type pruners. Bypass pruners are safe to use on living wood, whereas anvil pruners are meant to be used only when cutting up dead wood or kindling. If you’re working with branches that are too big to be cut easily with hand pruners, you can graduate up to either loppers or a saw. Hand pruners are generally useful for branches up to 1/2″ or so in diameter, loppers are effective for branches between about 1/2″ and 2″ or so, and then a folding saw becomes useful for addressing any cuts larger than about 2″. It’s up to your preference which tools you use, so get out there and try as many as you can to inform your decision when it comes to acquiring tree tools of your own.
With regard to making cuts, first keep in mind that trees do an excellent job of “compartmentalizing,” which allows them to close off to pests and disease after they lose a branch for any reason. However, there are a few basic points to follow to ensure that you’re making cuts the right way and not causing harm rather than doing good. Pruning is a form of “surgery,” so sharp pruners/loppers producing cleaner cuts hasten the tree’s ability to close the wound. Also, rubbing the blades with alcohol between trees (if you’re pruning more than one) can prevent the spread of disease, should one be present.
Finally, take a look at this illustration of what’s called a collar cut to learn how to remove a lateral branch connected to the trunk. The key to remember is not to cut into the branch collar because that’s where the healing hormones reside, so please read up on that if you’re not clear what that means.
Another thing we should consider is the timing of when to make your cuts. There are many who say trees can be pruned, “whenever the pruners (or loppers) are sharp.” Though that is generally true, do understand that it’s generally less stressful to prune deciduous trees when they are dormant (leaves have fallen for the winter). As a result, winter pruning of deciduous trees—including almost all fruits—invigorates the tree once it breaks dormancy. Summer pruning, on the other hand, will slightly reduce plant growth (though it will NOT ultimately create a smaller tree—the tree’s rootstock is what ultimately determines that). I’d recommend making larger cuts when the trees are dormant (say January through March in our climate) and lighter cuts when the trees have broken dormancy (June or early July). Furthermore, keep in mind that summer pruning is stressful on trees primarily because it opens up holes in the bark that allow water to quickly transpire in the heat of the season. That said, summer pruning should be followed by deep watering and mulch if there isn’t already a ring of it around your tree.
How much should be cut, you might ask? The amount you can cut each season can be referred to as the “pruning budget.” Cutting more than your pruning budget for a particular species causes more harm than it does good, so generally strive to cut only what you think really needs to be addressed. Before even considering how much needs to be removed, any dead/diseased/damaged branches should be removed immediately to reduce drain on the tree. Once that’s done, the general rule is that no more than 25% of what’s left should be removed in any one year. The first season, it’s important to identify the lateral branches (maybe four to seven or so) so you can focus on maintaining those in years to come. If you see any branches crossing, touching, growing inward toward the trunk, or competing with the “central leader” (or trunk), those would be your next priority if you’re lucky enough to still have space within your budget. If you find that you need to cut more than 25% to achieve your goals, consider a multi-year approach or try your hand at training or spacing.
Training or spacing are techniques we can use to save room in your pruning budget. In lieu of cutting branches, they involve bending, spreading, and otherwise manually manipulating branches for effect without the loss of canopy. I’ve used little notched pieces of lath after removing lath and plaster from my house, chopsticks, and even toothpicks, to space branches away from the trunk and create better angles. I’ve also hung fish weights and even small barbell weights from branches to encourage a more open canopy that invites sunlight and air circulation. Should you go the route of training rather than pruning, be sure to check up on your spacers and/or weights to be sure they’re not being consumed by bark from time to time. I once hung a weight from a branch only to realize a few short months later that the branch had grown so much the string cut right into the branch’s bark, forcing me to cut that branch off – exactly what I had not intended to do!
This is admittedly a very general guide, focused primarily on creating good weight-bearing architecture. If you are inspired, by all means, hit the internet and do more research! If you just want to get the basics down and get your tree off to a good start this first season, this guide covers more or less what you need to know. Remember: it’s OK to make mistakes while you’re learning, fruit trees are often quite forgiving, and your tree will survive and produce fruit even if you don’t make a single cut to it. No matter what, you’ve done your part to support our local food network, provide your household with delicious, nutritious, organic fruit year after year, and help keep Portland’s tree canopy dense!
If you find that you need clarification on these basic pointers, feel free to contact Andrew at 503-467-2518, and he’d be happy to fill in the blanks. There’s no better way to learn to prune than to just get out there and give it a try, so happy pruning!
–Land is Neighborhood Trees Specialist for Friends of Trees and is an ISA Certified Arborist.