Water sprouts and suckers (epicormic shoots): what the sources say

This page describes what the named sources say. It does not diagnose a tree, say whether any tree or growth is safe or unsafe, or tell anyone to cut, keep or treat one. Each cause and claim belongs to the source that gives it.

Words the sources use

The US Forest Service Southern Research Station defines epicormic branches as shoots arising from adventitious or dormant buds on the stem or branch of a woody plant, often after more light reaches the stem or after fire. University of Illinois Extension uses "epicormic sprouts" for vigorous shoots from latent or adventitious buds, calls those on root tissue "suckers" and those on stems and branches "water sprouts". The University of Maryland says suckers come from the roots or from the trunk below a graft union. The University of New Hampshire gives the same split and adds that most definitions put suckers at the roots or the base of a tree.

Where they come from

The Forestry Commission research note (Patch, Coutts and Evans, revised March 1989 and reviewed January 2005, issued by the Arboricultural Advisory and Information Service) says epicormic shoots usually arise from suppressed buds in the bark. These buds form on a growing shoot, fail to extend, and are carried in the bark as the stem thickens. It says a small amount of growth each year keeps them from being buried in wood, and that buds can also form out of sequence after injury or in callus over pruning wounds. It says the upper part of the tree appears to hold them suppressed by hormonal control, and that the influences involved are not well understood. New Hampshire says water sprouts and suckers grow from dormant buds in the bark and are weakly attached unless they have grown for many years.

Causes the sources name

Source	Causes it names
US Forest Service (Lockhart, Michalek and Lowe, 2006)	More light on the stem or fire. It says hardwood forest managers have also considered genetics and tree health as causes, and that the presence of epicormic branches is considered a sign of stress in a tree. In its east Texas red oak study, thinning and fertilizer made no difference to branch numbers on the butt log after five years, and numbers fell 79 percent between 1999 and 2003, which coincided with the end of a 3-year drought.
Forestry Commission note	In woodlands, thinning and overcrowding. In urban settings, severe crown pruning and pollarding, environmental stress, waterlogging, soil sealing, root severance during site development, or roots colonised by pathogens. In some species, insect defoliation or damage by weather or chemicals. It says genetics appear to control production in some specimens of common lime and Zelkova.
University of Maryland Extension	Pruning or removal of large branches, with heavy pruning giving more sprouts. Stress can also stimulate them, but those sprouts are usually less vigorous.
University of New Hampshire Extension	Stress or injury from storm damage, root loss, soil compaction, topping, disease, over-pruning or drought. It says crabapples, oaks, maples and dogwoods frequently develop numerous water sprouts, and that suckers can follow injury to the base of the trunk from mowers and string trimmers.
University of Illinois Extension	Stress, with the tree trying to develop more limbs, some pests or diseases, and age, since many trees sucker only as they mature. It names ornamental crabapples as prone, and failed grafts as a second reason on grafted trees.

How the sources describe the effects

The Forest Service abstract and the Forestry Commission note both describe a timber side: epicormic branches are considered defects that reduce the value of logs and lumber, according to the Forest Service, and the note says they can reduce the value of the butt length of a log. The extension pages describe a landscape side. Illinois lists poor limb structure, shading of the main plant and robbing it of nutrients and water. New Hampshire lists crowding the canopy, reduced flowering and fruiting, and greater susceptibility to wind and ice damage. The Forestry Commission note says that in urban areas the shoots may be visually unacceptable and become a hazard for pedestrians and vehicles.

What the sources list for management

The sources do not agree on a single approach. Maryland says water sprouts should be removed promptly and says one or more may be trained to replace missing branches. New Hampshire says that for a tree with many, the best approach is usually to leave some, because sprouts can help rebuild energy reserves, and that removing all of them without fixing the cause usually brings them back. The Forestry Commission note says mechanical pruning is costly, causes unsightly wounds and fails to prevent new shoots in later years, and that causal factors should be identified before chemical treatment is used. It also says replacement of individual trees noted for profuse production is the best long-term policy. The note's chemical products are not named here; for who may apply pesticides, see pesticide licences. How pruning cuts are described in standards is on the pruning standards page.

Where this ends

Whether a branch of any origin is sound is a tree risk question: see tree risk assessment. This page does not cover that. Root and soil disturbance during building work is on trees and construction.

Other growth forms are on the odd tree growth page.