The lone voice of horticultural reason
“Water suckers and shoots on trees should be pruned in the spring”
I suppose this myth persists because early spring is the time most people remove water suckers growing up around the base of trees, and water shoots (epicormic shoots) growing from trunks. Not much else to tackle in April.
Stem and root suckers grow up from the ground; a stem sucker grows from just below the graph union of a grafted tree (common example, an apple tree) while a root sucker grows up from a root (common example, maples, poplars). They are unsightly, cause depletion of water and nutrients from the main tree, and if left untended can eclipse the original plant in height.
Epicormic shoots form when buds on a trunk are activated by pruning. You cut a big branch off your oak, and two years later there are fifteen small branches coming out around the pruning wound. On a fruit tree (pictured), they are the light-colored, slender new branches that leap out vertically from the trunk, and from established branches.
Now is not the time to deal with any of these culprits. Spring is when things are coming to life. Prune suckers and shoots in the spring, and all they want to do is come back right away, with a vengeance.
Live with them this summer, then prune them in November, when the trees are going dormant. Do not paint with anything after pruning; you just need to stay at ’em each fall.
The Renegade Gardener