Issue: February 11, 2006

Black specks on pinon needles

The needles on my pinon tree have turned a yellowish-green color and, on closer inspection, I noticed tiny, pepper-like dots on the needles. The needles are not coming off the tree, but I am concerned as to what this might be. There are several trees fairly close by, including another pinon, and they are not affected. Is this possibly an insect egg?

These are not eggs but the insects themselves. The problem you described is pinon needle scale insects.

The black specks are the scale insects and their wax coatings. In late winter or early spring, the female scales will exit their protective coverings to migrate to the base of the tree and to the underside of branches to lay their eggs. The eggs will be in masses covered with what looks like dirty yarn. If these egg masses are removed with a broom or strong jet of water and taken away from pinon trees, the infestation will be greatly reduced for next year. A few years of this may almost eliminate the problem, but vigilance will be needed in case they return in the future. There are systemic insecticide sprays (such as acephate) that can be used. The application of insecticide must be timed to coincide with the emergence of the juvenile scale from their eggs. Apply the insecticide according to label directions. Do this in the spring when the newly hatched insects are ascending the trunk and branches to infest the newly formed leaves. (Sample periodically by holding a sheet of dark or very light construction paper under the needles and sharply strike the branch with a gloved hand.) Look for small insects moving on the construction paper. When you see them, apply the insecticide. However, it is often easier to treat by just removing the egg masses as described above.

Pollarding mulberry

I have found a lot of information about pollarding a fruitless mulberry but nothing about letting it grow in a more natural state. This year (in the spring) I will have a tree service prune the trees. I was told I would not have to do it for another year; however, the number of new branches is amazing. I feel as though some of these should be taken off before they bud. The trees are 20-30 feet tall. What would you suggest?

If a tree is properly pruned by pollarding (consistent removal of all growth back to a certain point) it should be done once every year or at least every two years. The advice to wait a year (if it was done last year) is appropriate. However, it is permissible to remove the growth every year.

Pruning a mulberry tree to maintain its natural form is the same as pruning any tree.Ê The mulberry tree can tolerate pollarding more readily than some other trees, so some books speak of pollarding the mulberry and do not discuss the general pruning techniques.

If you have not yet had the tree pollarded, then you can have natural-form pruning done. However, it sounds like you have already had the tree pollarded.Ê In that case, it is difficult to restore natural form. The branches you remove to restore the natural form will not be as well attached as if the pollarding had never occurred. These branches create a hazard as they enlarge, so pollarding once a year or every two years becomes important for safety reasons.

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.

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