Issue: January 17, 2004

Shredded mulberry as mulch?

I am about to cut back my Mulberry trees, and I would like to know if I can shred the branches (cut them into medium to fine pieces) and use the reduced pieces as mulch in my flower beds?

This is a good question to ask when you do not know the characteristics of plants. Some trees are known to produce allelopathic compounds (compounds toxic to competing vegetation). Thus far, only a few species of trees, some grasses, and some other plants are known to produce allelopathic compounds. Mulberry was not listed among the producers of inhibitory chemicals.

You should have no problem using shredded mulberry wood and bark as a mulch. They should work very well. Using tree prunings to make mulch is beneficial to the environment and does not create a problem of unnecessary waste being sent to the landfill.

Chamisa (rubber rabbitbrush) allergy

I understand that my chamisa plants may be causing my allergies. Is that true? Should I cut them down?

What kind of allergic response are you experiencing? Have you had the allergic response confirmed by an allergist to be due to the chamisa or rubber rabbitbrush (Chrysothamnus nauseosus)?

The pollen of the chamisa is known to cause allergic responses in some people in the spring. However, other people accuse the chamisa "fluff" in the autumn. I usually associate allergies with proteins which are present in pollen but not in the fluff. In searching the Internet, I learned that "anything can be an allergen causing an allergic response". Non-proteinaceous materials must bind to a protein in the body to be an allergin, but some people are allergic to some non-proteinaceous materials. Perhaps you are indeed allergic to the fluff from the chamisa.

There is another possibility that the chamisa is the victim of circumstantial evidence. At the time that the chamisa is shedding seed attached to the fluff, other known pollen allergens are present in the air. Many weeds and grasses produce aeroallergins in the autumn. The fluff is more visible than the pollen and is often unfairly credited with being the culprit. The only way to know for sure is to see your allergist and confirm the cause of your allergy.

If the chamisa is confirmed to be your problem or, if you just wish to replace the plants in your landscape, of course you can cut it. In some parts of the state, chamisa is a common native plant and used in neighboring landscapes. You may not totally eliminate the problem, but you can increase your distance from it and reduce your exposure to the fluff. Another thing to consider is that chamisa is very flammable and not a good plant to use as a foundation planting next to structures. In the event of a range or forest fire (or carelessly discarded cigarette), it can increase the risk of damage to your home.

Otherwise, the chamisa is an excellent, beautiful, water-conservative plant for southwestern landscapes and is highly recommended.

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!