February 23, 2013

1 - Pruning is best done before new growth begins in the spring, but removal of dead branches can be done at any time.

Yard and Garden February 23, 2013


The tops and ends of branches on the mulberry trees on our street died last year after a severe winter. We homeowners want to trim off all the dead branches on the top and ends of lateral branches, leaving the living parts to continue to grow. We thought we should wait until the leaf buds form so that we know how much to cut back each branch (to the live buds). Is this a good idea, and if so, when do you think the leaf buds will become visible?

Susan B. and others in the UNM area



If you can tell what is dead and what is alive, now is a better time to prune trees. A common guideline is to prune before the buds swell enough to "reveal color". The dead twigs and branches are often distinguishable by their bark (peeling or split), brittleness, or other visible characteristics. Do not just cut back anywhere. You should prune away the dead branch back to a living bud or healthy branch. If this is a neighborhood project, you may be able to share costs and hire a certified arborist to properly trim the trees. A good arborist should be able to easily distinguish dead branches and twigs now, especially if these are branches that have been dead for over a year.

Since you are considering trimming mulberry trees, the time factor is somewhat less critical. Mulberry trees are usually very vigorous and can often be trimmed even after leaves have formed without seriously damaging the trees. Once the leaves have formed, it is very easy to distinguish between the living and dead branches. Even so, proper pruning back to a healthy bud or branch is important. Proper pruning also involves pruning just outside the branch collar, the swelling at the juncture of two branches that indicates the point where tissue from one branch overgrows the other branch. Pruning to leave the branch collar means to prune in the manner that best allows the tree to close the pruning wound while excluding disease organisms.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


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