Issue: March 29, 1999

Dying spruce needles

The tips of my spruces are dead and shriveled - not drastically, but each tree shows some sign. What causes this and how can I treat it?

There are a number of things that could cause this problem. One is the presence of the spruce bud worm, but you should see some webbing and frass, perhaps even the worm. There are products labeled for use in control of this pest.

This year I have seen a lot of dried, bronzed or brown needles at the tips and interior needles of spruce trees. Factors causing a lot of this include the rather dry winter. In addition to being dry for a good part of the winter in many places, it was rather warm as well. If there is little moisture in the soil under these conditions, needles will be damaged. The places where the needle damage is the worst, however, are where de-icing salt was used during the infrequent snow and ice periods. As the salt melted the ice, the salt and ice mixture permeated the soil and entered the spruce root zone. De-icing salts, especially those containing sodium chloride, are damaging to spruce trees. The salt damage done is worsened by the dry winter conditions.

It may be possible to leach the salts from the root zone by slow, deep watering to dissolve the salts and wash them below the majority of the absorbing roots of the spruce. This should be done infrequently so that the root zone doesn't remain waterlogged. When watering, water very deeply, allowing the water to slowly soak into the soil, then let it dry between irrigations. If the soil contains a lot of clay and is slow to absorb water, you can use a spading fork or other device to create holes in the soil to reduce runoff and enhance water infiltration into the soil.

Transplant forsythia

I have a forsythia that was planted too close to our walkway. I have to radically cut it back each year so it doesn't block the entrance to our front door. Can it be transplanted to an area of the yard where it can display its full beauty?

Now is not a good time to transplant forsythia in all but northern most New Mexico and high elevations. Once the buds have begun swelling, delay transplanting until late next fall or in the winter when the plant is dormant.

In anticipation of such a move, you can root prune the shrub this year by digging a narrow trench a couple of feet from the base of the plant. This cuts the roots. Then refill the trench with a good compost and soil mixture. This provides a good medium for growth of new roots from the cut roots. When you transplant the shrub, dig it just outside this area of improved soil so that you have new, young, vigorous roots with the transplanted shrub. As you dig the trench, remember that this is where you will dig the shrub next year and the bigger the root ball, the better it is for the plant but the more difficult it is for you to move it. A compromise may be in order.

Finally, to be practical, if it is essential to move the shrub now because it is in the way, you can move it. There will be greater transplant shock. With greater transplant shock, the shrub will be slower to establish in a new location and take longer to become the beautiful shrub that it is capable of becoming in a large enough area. Greater transplant shock increases the chance that the shrub will die. If it is necessary to move it now, use good planting techniques and be sure to provide adequate water with a brief drying period between irrigations.

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!