Hold off on pruning your crabapple tree until after the first killing frost of the season to ensure that it has gone dormant. In a pinch, it’s okay to prune in early summer after the tree has finished blooming, although this can increase the risk of “fire blight” and other warm-weather diseases. Aim to have your pruning finished before June (or December, if you’re located in the Southern hemisphere). [2] X Research source
It may also help to have a pair of telescoping loppers to remove smaller stems and offshoots high up in the canopy of the tree. [4] X Research source
The first undercut you make will prevent excess bark from peeling off the trunk once the limb comes free. [6] X Research source Avoid cutting perfectly flush with the trunk. Insects and disease-causing organisms can easily find their way into the tree through open wounds in the trunk.
If you’re unsure whether particular branch is dead, scrape the wood with your fingernail to remove a portion of the bark. If the flesh is underneath is green-white, it’s still alive. If it’s brown or black, it’s most likely dead. Keeping your crabapple tree free of dead wood is a good idea at any time of year, since it’s more likely to introduce disease.
Removing inward-growing branches will give the tree a neater, more uniform shape.
If you decide to remove only one branch, single out the one that looks weakest or most awkwardly placed.
Remember to make your cuts as clean as possible so that no stumps remain. If your tree’s lower branches aren’t causing a problem, it’s usually best to let them stay.
Basal suckers most often originate at the rootstock that the crabapple was grafted onto. If left alone, these tiny branches can develop into whole new trees, complete with different flowers and fruits. [12] X Research source Removing suckers as soon as you spot them will redirect energy to the parts of the crabapple tree you want to preserve.
Try to catch emerging water sprouts when they’re still young and green. At this stage, you’ll be able to simply pull them off by hand, which makes it harder for a new one to grow in its place. Too many of these undesirable shoots can crowd out the other branches and reduce airflow within the tree, leading to disease, rot, infestations, and other complications.
The tree’s upper crown is especially likely to produce an overabundance of water sprouts if cut back too much. Never remove more than 20% of your crabapple tree’s total live growth in one year. Doing so could severely stunt its growth or even kill it. [15] X Research source
Trees affected by fire blight typically have branches that appear burnt or blackened, and may produce shriveled, “mummified” fruit. If your notice fire blight on a major limb, you may be able to save it. Try scraping off the outer layer of bark all the way down to the healthy tissue underneath to ensure that the disease doesn’t spread.
Always disinfect your gardening tools thoroughly to prevent disease from spreading from one part of the tree to another. The simplest way to do this is to dip the blades in rubbing alcohol before making each new cut. If the trunk or root system of the tree appears to be infected, it may be too late to save it.
