![](https://webarchive.library.unt.edu/eot2008/20090122120230im_/http://www.cdc.gov/nasd/images/line.jpg)
Diane Relf
Virginia Cooperative Extension
Every
year, thousands of people suffer from allergies, a condition
known as seasonal allergic rhinitis. Most allergy sufferers
attribute their discomfort to plant pollen of all types and
have pursued governmental regulation of plants, mostly ornamental
specimens, thought to cause allergic reactions. The truth
of the matter is, not all pollen causes these seasonal reactions,
and there is no steadfast rule as to what types of plants
are producers of allergens. Sometimes, it's not the obvious
plant causing the allergic reaction. For example, when ragweed
pollen is disbursed, many people have a reaction, but since
they don't see the tiny flowers on the ragweed, they assume
it's the pollen from the larger flowered goldenrod which blooms
at the same time.
Allergy
suffers have waged a war against the plants considered to
cause the greatest problem -- those that are wind pollinated
and produce huge amounts of small, very fine pollen. Unfortunately,
this is not always the case, since plants like pines and true
cedars depend on wind for pollination and produce great amounts
of waxy-coated pollen, but they do not stimulate a reaction.
Plants with colorful or fragrant flowers, usually insect pollinated,
are considered "safe," non-allergenic plants because they
produce their large, heavy pollen grains in relatively small
amounts. The pollen are covered with a sticky substance and
are not usually carried by wind. Some insect-pollinated plants
do, however, produce pollen in amounts large enough to cause
allergic reactions, such as Russian Olives and Willows.
Plant
pollens are not the only allergens causing severe reactions.
Many molds and mildews are a large source of spores that affect
people all year round. Other factors, such as air pollution
and dry windy conditions, accentuate allergic reactions. The
individual's environment also influences hypersensitivity
to allergens (substances causing a reaction) -- the greater
the exposure, the greater incidence and degree of illness.
To avoid
acute allergy problems in the home landscape, several steps
can be taken. Individuals suffering from allergies can make
informed decisions about plant materials least likely to cause
attack, choosing "safe" plants that have large or sticky pollen
grains not likely to be transported by wind and female cultivars
which do not produce pollen at all. Keeping grasses mowed
to appropriate heights decreases their pollen production.
Weeds, molds, and mildews should also be controlled. If there
is an existing pollen problem in your landscape, replace that
plant with a less allergenic selection.
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and Reproduction Information: Information in NASD does not represent
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NASD Review: 04/2002
Diane
Relf, Extension Specialist, Environmental Horticulture
August
1996
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