Allergies, Asthma and City Trees

Written by Thomas Ogren

Continued from page 1

How to Improve Health and Air Quality through Tree Selection Landscaping to reduce allergies, especially pollen allergies, is an idea that is coming into its own. Inrepparttar past few years several books have been written onrepparttar 110107 subject and interest is growing rapidly. Withrepparttar 110108 addition of OPALS™, (Ogren Plant-Allergy Scale) arborists now have a means to design allergy-free plantings. This scale ranks all landscape plant materials on a simple 1 to 10 allergy basis. Trees that produce zero pollen, e.g., female cultivars, usually rankrepparttar 110109 best – number one. Trees that have abundant, highly allergenic pollen, especially those with very long bloom periods, are usually rankedrepparttar 110110 worst – inrepparttar 110111 9-10 range. There are many trees and shrubs, however, that fall somewhere in between. Using a list of over 100 factors, OPALS™ numerically ranks each species and then further ranksrepparttar 110112 individual cultivars. There are often dramatic allergy differences even between two species inrepparttar 110113 same genus.

How Are Plants Allergy-Ranked? OPALS™ was developed based onrepparttar 110114 following considerations: “What do plants that are well known to cause allergies have in common?” and “What do plants that are well known NOT to cause allergies have in common?” With these two questions it was possible to build two opposing sets of medical-botanical-allergy criteria. One set is positive and one set is negative. Examples of negative criteria: tiny flowers, excerted stamens, small (less than 25 microns in diameter) sized pollen grains, extended bloom period. Examples of positive criteria: complete flowered, sticky, heavy pollen grains, presence of nectaries, brief bloom period. There are now over a hundred criteria used to develop OPALS™ rankings. Individual landscapers, city arborists,repparttar 110115 USDA andrepparttar 110116 American Lung Association have already userepparttar 110117 scale to make better landscaping decisions. Based onrepparttar 110118 plant-allergy scale it is now possible to state, for example, that Acer rubrum – ‘Red Sunset’ maple, is ranked number one and causes no allergies. By comparison, ‘Autumn Spire,’ a male cultivar of red maple does cause allergies and is ranked number nine. Most Pine trees will rank at numbers 4 to 5 and will cause some allergy. Platanus species (sycamore) rank number eight, and cause quite a bit of allergy. A male Canary Island Palm, Phoenix canariensis, which is considered one ofrepparttar 110119 worst at a ranking of 10, will produce an abundance of pollen that will cause severe allergic reactions to many living nearby. Pollen dispersal rates have been measured since 1972 (Gilbert Raynor, NY meteorologist) and although many pollen grains travel far inrepparttar 110120 air, research shows that most often 99% of a tree's pollen falls out and sticks within fifty feet ofrepparttar 110121 tree. This means thatrepparttar 110122 closer one is torepparttar 110123 pollinating treerepparttar 110124 greaterrepparttar 110125 exposure. Thus,repparttar 110126 job for arborists is to plant trees that will not expose everyone near them to allergenic pollen.

So, How Do You Tellrepparttar 110127 Boys fromrepparttar 110128 Girls? It isn’t always that obvious by looking at a tree (especially a young tree) as to whether or not it is a pollen-free female or a pollen-producing male. But since so many city trees are now asexually produced cultivars,repparttar 110129 sex is predetermined. Inrepparttar 110130 book Allergy-Free Gardening, which isrepparttar 110131 result of 15 years of research on this subject, several thousand trees were individually sexed and allergy-ranked. In some cities, pollen control ordinances are already onrepparttar 110132 books, although most of these could be improved an updated. Albuquerque, New Mexico is particular interesting, since it has attempted to curb allergies by prohibitingrepparttar 110133 sale and planting of any male cultivars. Asrepparttar 110134 public grows more knowledgeable about allergy-free landscapes, municipal arborists and landscape specialists will want to be ahead ofrepparttar 110135 curve. They will want to show their clients that they are well-informed onrepparttar 110136 subject. Inrepparttar 110137 future, instead of planting high allergy-trees, they will need to plan and plant ‘healthy’ urban landscapes.

References: 1.Lewis, Walter H., Airborne and Allergenic Pollen of North America, John Hopkins University Press, Baltimore, Maryland, 1976. 2.Jacobson, Arthur Lee, North American Landscape Trees, Ten Speed Press, Berkeley, California, 1996. 3.Koch, Christopher Von, Allergy, Die Woche, pg. 27, July 7, 2000, Hamburg, Germany. 4.Dworschak, Manfred, Der Spiegel, Feind am StraBenrad, Pp. 174, 175, Nr. 29, 2000. 5.Ogren, Thomas Leo, Turn Backrepparttar 110138 Pollen Clock, New Scientist, London, Pp. 46, 47, June 3rd, 2000.

Thomas Ogren is the author of Allergy-Free Gardening, Ten Speed Press. Tom does consulting work on plants and allergies for the USDA, county asthma coalitions, and the Canadian and American Lung Associations. He has appeared on HGTV and The Discovery Channel. His book, Safe Sex in the Garden, was published in 2003. In 2004 Time Warner Books published his latest book: What the Experts May NOT Tell You About: Growing the Perfect Lawn. His website:

Cottonwood “cotton” is flying/ Bad Company

Written by Thomas Ogren

Continued from page 1
Also to take into consideration is that byrepparttar point inrepparttar 110106 year whenrepparttar 110107 cottony seeds ofrepparttar 110108 willows and poplars starts to float about, most ofrepparttar 110109 male maples and male ash, and a large number of other trees and shrubs have already released their own pollen. Unless this pollen was washed away by strong downpours of rain, much of it is still lying about, and is still causing problems, weeks or sometimes even months after it was released. To add to all ofrepparttar 110110 above, at precisely this same time,repparttar 110111 grasses start to release pollen. The ornamental landscape clump grasses all produce huge amounts of pollen at this time, as do most bluegrass species, bentgrasses, Bahia grasses, and especially Bermuda lawns that have not been kept closely mowed. Byrepparttar 110112 way,repparttar 110113 newer hybrid Bermuda grasses are sterile and pollen-free, but notrepparttar 110114 old common Bermuda lawns by any means. Byrepparttar 110115 time this poplar and willow “cotton” is inrepparttar 110116 air, many people with allergies are already starting to suffer from “systems overload.” There is so much pollen being released and so much just previously released, that it overwhelmsrepparttar 110117 immune systems of many individuals. The result of course is allergy. The sad thing about this whole affair is that all too often these female willows or female poplars, female cottonwoods, female aspens, they get blamed forrepparttar 110118 pollen fromrepparttar 110119 male trees and then people cut them down! Since female trees have flowers that are electrically charged negative - (their roots are grounded) and since pollen from male trees picks up a positive + charge as they tumble about inrepparttar 110120 air,repparttar 110121 two are mutually attractive. Female trees are powerful air cleaners, air scrubbers. Every female tree that is chopped down makesrepparttar 110122 air in that neighborhood that much more allergenic. We need to protect our females!

Thomas Ogren is the author of Allergy-Free Gardening, Ten Speed Press. Tom does consulting work on plants and allergies for the USDA, county asthma coalitions, and the Canadian and American Lung Associations. He has appeared on HGTV and The Discovery Channel. His book, Safe Sex in the Garden, was published in 2003. His website:

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