Issue: June 2, 1997
Leaves and twigs falling from trees
Question:Recently many twigs with new leaves on them have started falling from my trees. I have seen leaves fall after winds in the late spring, but this is twigs falling. What is wrong with my trees?
Answer:If you will remember, we had a cold spell with frost which occurred after leaves were on the trees. Looking at the sample you sent, it appears that the new twigs were damaged by the frost. This damage affected the outer layers of the twig, the phloem and cambium, but not the xylem. The xylem carries water from the roots to the leaves, the phloem carries the food produced by the leaves to the rest of the tree, including the roots. The cambium is the layer which produces new xylem and phloem. When the phloem and cambium are damaged and the xylem not injured, the water needed by the leaves can proceed from the roots to the leaves, so the leaves look normal. Because of the injury to the tissues at the base of the twig, however, the twig has been weakened and easily blows out in our New Mexico winds.
I have observed this in a number of trees, and in the absence of symptoms of disease don't consider this a problem about which to be overly concerned. You may notice that some branches have considerable dieback and that more dieback and other weak growth as the summer progresses. It is a good idea to remove the dead and dying branches as they appear. As long as the majority of the tree appears healthy, it should survive. Be sure to provide adequate water through the summer as the heat and dry winds will increase the stress on the trees.
Birds eating my cherries
Question:I am mad! Most of my cherries froze just after they formed from the blossoms. Now the birds are eating what is left. How can I get rid of the birds? I don't want to kill them just to keep them away from the cherries.
Answer:Covering the tree with netting is the usual best answer. And it is not that good an answer. Large trees are hard to cover. If the netting doesn't reach the ground on all sides of the tree, you will find some very fat birds under the net enjoying your precious cherries. If there are cherries near the netting so that the birds can reach them from the outside, the birds will perch on the netting and peck all the cherries they can reach.
Other gardeners use scare tactics. Most birds are easily startled and that is a characteristic we can use to our advantage. First, the rubber snakes and plastic owls don't effectively startle the offending birds. They rapidly become accustomed to the non-moving scare objects. Something that moves is more effective. That is why many gardeners hang aluminum pie plates in the tree. These blow in the wind, twisting, clanging, and flashing sunlight at the birds. Other gardeners use strips of aluminum foil. I have also seen ribbons of surveyors tape strung between trees and branches so that they twist and sway in the breeze. These may be somewhat effective. I have also seen gardeners tie cans with rocks in them to branches in the tree, then run a string to their back door or window so that they can pull the string, moving the branches and rattle the rocks in the cans. This was effective as long as it was used frequently.
Perhaps a combination of netting and scare tactics will be helpful to you this year since there are very few cherries to share with your feathered friends. Good luck.
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 and the NMSU Horticulture Publications page.
Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.
Please copy your County Extension Agent and indicate your county of residence when you submit your question!
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