Issue: September 25, 2004

Aphids in globe willow

I recently removed a globe willow tree in our yard that was infested with aphids. Following the recommendation of a nursery, I applied an insecticide several times over the past 2 months. It did not work, and the tree continued dying branch by branch. The stump has been removed, and I was planning on leaving the area fallow until spring. I will plant another tree at that time, possible a peach. Is there anything that I should use to treat the soil before replanting in the same hole?

Gary B.
Las Cruces

Based on what you have written above, I think there is nothing to worry about if you replant at the same site without treating the soil. It is wise to plant something besides a globe willow at that site in the unlikely event that there was a disease involved. The aphids may have weakened the tree but are probably not the ultimate cause of tree death.

The globe willow tree is subject to many problems other than aphids, which are common on globe willow. There are borers that may attack and cause gradual branch dieback, and the drought makes it difficult to provide enough water to the willow. Lack of sufficient water can cause branch dieback.

Neither borers nor drought create a residual problem in the soil. Drought is, of course, related to soil moisture, but proper irrigation remedies that problem.

When to bring in Christmas cactus and poinsettia

I know you have answered this before, but when should I bring my poinsettias and Christmas cacti indoors to begin putting them in the closet each night?

As long as the plants are in an area away from porch lights and street lights that would interfere with the process of floral induction, they do not need to be indoors until temperatures drop to near freezing. The process of floral initiation begins as the days shorten (nights lengthen beyond 12 hours) at the autumnal equinox. Lowering temperatures are important in this process as long as the temperatures are well above freezing. Indoor temperatures tend to be warmer, so being outdoors is beneficial as long as the long night requirements are not interrupted by lighting. However, when temperatures begin to drop below 50 degrees at night, bring the plants indoors and continue the long night treatments by placing them in a dark closet at night or by covering them at night with a dark cloth. Return them to the light once the sun is up.

If you want to read the previous Yard and Garden articles on this or other topics, they are available at the NMSU College of Agriculture web page. The specific page to check for Yard and Garden is http://www.cahe.nmsu.edu/ces/yard/swyg.html. On that page use the "archives" section or the search box, both on the right side of the page.

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!