||Information for patients with allergy and related
in the Southwest
Environment and allergic disease
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Gardens Compatible with Respiratory Allergy in Southern and Central
Why bother with low allergy horticulture?
It may seem unlikely that reducing the number of allergenic plants in a single garden
would make a difference to a sufferer of allergic disease. Nonetheless, it is
important to limit the spread of allergenic plants because a collective effort by as many
of us as possible could have a real impact on the levels of pollen in our atmosphere.
Eliminating allergenic plants close to dwellings can reduce symptoms of occupants
who have allergic respiratory disease. Pima County government has recognized this
problem for many years and established ordinances to limit the pollen from Bermuda Grass,
Olive trees and Mulberry trees.
We are planting new allergens.
Although many exotic imported species that are wind pollinated (e.g., Australian Saltbush,
Atriplex semibacata) are not yet prevalent, they could become a real problem if
their introduction into the landscape continues. All species of Atriplex are very
allergenic. Jojoba, a native species, is wind pollinated and may also
become a common allergen with its increasing popularity in landscaping.
- All species of grass are allergenic, with the exception
of a few hybrids.
- Bermuda grass
(Cynodon dactylon) is the most frequent sensitizer in Southern Arizona.
Remove it from domestic gardens and from dirt alleys whenever possible, remembering that
its roots must be killed by application of Roundup to actively growing grass in the summer
to prevent regrowth. Neglecting a Bermuda grass lawn by failing to water it will NOT
kill it. Nonflowering hybrid Bermuda grass, e.g. Tif, is available, but that lawn
should be watched for contamination with wild Bermuda grass over time. St. Augustine
Grass also seldom seeds, but is poorly suited to Arizona conditions.
- Dichondra (not a grass) is a lawn substitute, but needs
plenty of water and is good rabbit food.
- Buffelgrass is an invasive and
prevalent weed in Southern Arizona. It could become a significant allergen in the
- Not all weeds produce allergenic pollen. However, plants
with inconspicuous flowers are usually undesirable in a garden and hence are called
"weeds." Inconspicuous flowers usually produce wind-borne pollen, which
can cause allergy.
- To rid your garden of summer weeds and winter weeds
consult your local University Agricultural extension service.
Flowers, small plants and shrubs
- Brightly colored flowers that attract bees and other
insects or humming birds are generally not allergenic.
- Triangle Leaf Bursage (Rabbit Bush, Ambrosia
deltoidea) is very allergenic and should be removed
- Desert Broom (Baccharis sarothroides) is
allergenic for some people and should be removed
- Regular trimming of large shrubs to remove allergenic
flowers e.g. Privet, is important.
- Choose plants from the List
of ground cover and flowers , List of shrubs and List of vines
Succulents and Cacti
- Avoid planting wind pollinated trees near dwellings.
- Planting of Olive trees (excluding the Swan Hill and
Wilson varieties) and Mulberry trees is illegal in Pima County.
- Bamboo and palms are related to grasses but are rarely
allergenic in Arizona. See List of palms.
- Choose trees from the List
of trees . Those species (trees and palms) in which selection of female plants
is important pose a problem, because sex determination of the plant is impossible until it
is large enough to flower.
- Fruit trees are not allergenic, but most nut trees are.
- Although citrus flowers are not allergenic, the fragrance
from citrus trees can be irritating for asthma patients.
Regulations for Pollen Control in Pima County
Control of pollen from
Bermuda grass, Mulberry trees and Olive trees is regulated by General Ordinances in Title
7, Chapter 7.41 of the Pima
Establishing a Garden in Arizona
Advice on establishing gardens in the desert that are environmentally
responsible is available from the University of Arizona Garden Extension Services.
Ogren-Thomas, L. Allergy-free gardening. A revolutionary approach to
landscape planning. Ten Speed Press, Berkeley, 2000
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Disclaimer: This site is for educational
purposes only. Any information that you have found in this web site is not
intended to replace medical care or advice given to you by your own physicians. You should
consider consulting your local medical library and other web sites for additional
Comments and suggestions welcome! Email: email@example.com
Content Owner: Michael J. Schumacher, MB, FRACP, The
University of Arizona