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April 6, 2013

1 - It is best to prune fruit trees before they bloom, but later pruning may also be done.

2 - Pine needles are good mulch for the garden.





Q. #1 My fruit trees are already blooming. Is it too late to prune them?

Albuquerque

A. #1

You can still prune your trees, but you have missed the best time to prune. Once the tree begins blooming, energy produced by converting stored carbohydrates is expended to produce the flowers and new growth. Pruning now robs the plant of that energy. However, the longer you wait now, the greater the loss of energy. That energy was stored in the tree to produce new growth and to help the tree resist diseases and environmental stresses. If you prune too late, the plant will draw deeper into its reserves and use the carbohydrates that should be reserved to produce energy for maintaining plant health.

The health and physical condition of the tree should be taken into account. A young, vigorously growing, healthy tree can tolerate the injury of late pruning better than older trees and trees in poor health. The environmental conditions that the tree will face this summer may challenge the tree, so you will do the tree a favor to minimize the loss of stored carbohydrates. Never the less, it is sometimes necessary to prune for safety to remove branches that are poorly placed and causing safety issues. Such pruning can be done whenever necessary.

Many fruit trees were injured by the recent cold weather. This caused flowers of many apricots, plums, and pears to freeze. The result will be a poor crop of fruit this year, but the trees will be able to direct more of their carbohydrates produced by photosynthesis into storage, growth, and protection from stress instead of into fruit production. This is another factor you can consider as you debate whether or not to prune.

Q. #2

I collected a large pile of pine needles from my trees last winter. I have heard that they are not good to use for mulch or compost. Is that true?

Louise D.

Santa Fe

A. #2

Pined needles make excellent mulch. They decompose slowly (the reason they often rejected for composting), and they shed water, not absorbing it themselves. They let the water pass through to the plants they are protecting as mulch. In the heat of summer, the fragrance of pine needles can be a pleasant addition to the garden.

Many people assume that pine needles are not good for mulch because few plants grow through the layer of old pine needles under a pine tree. The reason so few plants grow under a pine tree is the fact that the tree sheds water to the dripline, maintaining a relatively dry environment under the tree that inhibits seed germination. A second reason is that the slow to decompose pine needles accumulate to a depth sufficient to block light from the soil. Many weed and other plant seeds need light to germinate. This characteristic is a great characteristic for mulch. You do not want weeds germinating around the plants you have mulched.

For more gardening information, visit the NMSU Extension publications Web site at http://aces.nmsu.edu/pubs/_h, or to read past articles of Yard and Garden go to http://aces.nmsu.edu/pubs/periodicals.html

Send your gardening questions to:

Yard and Garden, Attn: Dr. Curtis Smith
NMSU Agricultural Science Center
1036 Miller Rd.
SW, Los Lunas, NM 87031.

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist emeritus with New Mexico State University's Cooperative Extension Service. NMSU and the U.S. Department of Agriculture cooperating