Allergy problems are worse today than ever
before in our lives. Deaths from asthma continue to climb each year at an
alarming epidemic rate.
our urban landscapes we now have the most manipulated kind of city forest ever
seen. In the past twenty years landscapers have grown inordinately fond of
using male trees. In dioecious species (separate-sexed) there are separate male
trees and separate female ones.
Female trees and shrubs do not produce any
pollen, ever, but they do produce messy seeds, fruits, old flowers, and
seedpods. Landscapers and city arborists consider this female byproduct to be
litter, and they dont like to see it lying on our sidewalks.
a result we now have huge tracts of these litter-free or seedless
landscapes in our cities. What these actually are, of course, are male clones.
As males their job is to produce pollen, and that they do! Even though in many
cities we have less total vegetation than we used to, we have more pollen in
our air now than ever before.
nature separate-sexed plants are usually about 50/50. Half of them are male and
half are female. The female plants catch pollen from the air, remove it from
circulation, and turn it into seed. Female trees are natures pollen
traps, natural air-scrubbers.
our modern cities though, female trees and shrubs are rarely used any longer.
Of the five most available street trees for sale now, four of the top five are
Because no one bothered to consider the effect of the pollen from these male
trees, we now have many elementary schools, ringed with male shade trees, and
full of asthmatic children. Pollen counts exceeding sixty thousand grains of
tree pollen per cubic yard of airspace have been found in elementary school
yards. What does this mean? Simply, it means that on these playgrounds, every
child there is inhaling several thousand grains of allergenic pollen with each
breath of air they take! And people are surprised that childhood asthma is so
the past experts have criticized the concepts of allergy-free
landscaping by saying that, It doesnt matter what you plant in your
own yard. Pollen will just blow in from somewhere else.
What these so-called experts failed to
mention is that the closer you are to the source of the pollen, the more you
get. In some ways it is quite similar to second-hand smoke: If someone is
smoking a block away from you, yes, some of that smoke might reach you.
However, simple common sense tells us that this isnt at all the same as
having someone smoking right next to you. A large male tree in your own yard
will expose you to more than ten times the amount of pollen as would a similar
tree just down the block.
what are we to do? In my book, Allergy-Free Gardening, July 2000,
Ten Speed Press, I strongly suggest we embrace the politics of pollen. At least
five cities in the US now have some form of pollen control ordinance: Tucson,
Phoenix, Las Vegas, El Paso, and Albuquerque. We need to do several things and
we need to do them quickly.
We need city-by-city local ordinances that forbid the further sale and planting
of wind-pollinated male clones of trees and shrubs. Enough already!
We need to train people in tree grafting so that they can get started changing
the multitude of male trees into female trees. Yes, we can give these trees
much-needed sex changes and we ought to get with it. This is surprisingly
effective and quite easy to do.
All landscape plants for sale in nurseries should be required to have a
numerical allergy rating on each container. OPALSä already exists and
needs to be used. With this system: 1 = least allergenic, and 10 = most
We need to ask ourselves and our elected representatives these two questions:
How much more allergy is acceptable? How many more children need to die from
asthma each year before we decide to put an end to these destructive landscape
I think the answer is obvious. We need to get started now. Press Here!
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Email:Thomas L. Ogren