June 8, 2013

1 - Summer is a good time to prune dead branches, but be sure they are dead.

Yard and Garden June 8, 2013


My trees have finally produced leaves on most of the branches. Some branches have no leaves while others have a few leaves. Can I prune these branches now?


Yes, you can prune away dead branches and weak branches in late spring and summer, but be sure that they are really dead. Summer is the best time to identify dead branches to remove. However, this year many trees were slow to produce their leaves because of drought. Many of the branches on your tree may actually be alive, though they may appear to be dead. You can confirm the status of a branch by looking at the cambium layer just under the bark. If the branch is dead, the cambium will be brown or gray. A living branch will have a green cambium layer. Cambium is the layer of cells near the outer edge of a branch or twig that are living and actively dividing to form cells necessary for the transport of water up and down the branch. If the cambium is dead, new cells to carry water upward to the twigs will not be formed. If the cambium has been injured, but not killed, by winter cold or drought there will be fewer cells to transport water upward to support new leave development. This will result in slow development of leaves. This is the reason you should carefully check the status of the cambium before pruning apparently dead, or mostly dead, branches. They may be injured, but not dead.

If the whole tree is forming few leaves, a wise gardener may choose not to prune injured branches that are slow to form leaves from the tree. The leaves may be needed to produce food to support recovery from the injury.

If the tree has some branches developing leaves normally and other branches that are forming no new leaves and the cambium on those branches is dead, the branches with dead cambium may be pruned away without doing any harm to the tree. The weaker branches may also be good candidates for pruning, but consider the effect of pruning on the structure and appearance of the tree. Some weak branches may be left to maintain a balanced appearance for the tree. These branches may recover over time, or they may die and can be pruned after dying.

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.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

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