Charles L. Wilson
Charles L. Wilson is a writer and consultant living in West Virginia, USA. The present article is a revised and updated version of one that appeared in Journal of Forestry (Vol. 72 No. 2, February 1974).
· Tree pollen Is the primary cause of early-spring hay fever. Although this type of hay fever is generally mild and of short duration, some individuals suffer rather violent reactions. In selecting tree species for urban environments, it may be wise to consider the allergenic qualities of their pollen. Large populations of trees that produce allergenic pollen should be avoided.
The fact that tree pollen is responsible for only a small proportion of the total number of hay-fever and asthma cases is of no comfort to those who are sensitive to such pollen. For example, Balyeat and Rinkel (1932) report that in two cases they were able to control sensitivity to many pollens and animal epithetelium (cellular tissues) but were unable to control sensitivity to paper-mulberry pollen. The severity of asthmatic symptoms during the paper-mulberry season was so marked in these two cases that both individuals had to move to areas where this species does not grow.
The hay-fever season is usually divided into five periods: early spring, late spring, early summer, late summer, and winter. The dates and duration of these periods vary among different geographic regions. Plants responsible for allergenic toxicity also vary in different regions. Wodehouse (1986, 1971) describes seasonal pollen production by various plants in different regions of the United States.
Which trees cause hay fever?
For pollen to cause hay fever, it must be produced in large quantities, be disseminated by the wind and possess allergenic toxicity. If a tree is pollinated solely by insects, it can be ruled out as an important cause of hay fever.
Trees that cause hay fever are all wind-pollinated, except the maples and willows. But even here insect pollination is imperfect, and some pollen is wind disseminated. Some species of maple, such as the box elder, are entirely wind-pollinated, as are some of the willows.
Some tree species produce large quantities of wind disseminated pollen that is not an important cause of hay fever. An outstanding example is the prodigious amount of pollen produced by species of pine, which has very little, if any, allergenic toxicity. The allergenic toxicity of pollen is usually a characteristic shared by families of trees.
The hay fever families
Among the important hay-fever-causing families of trees and shrubs, Wodehouse (1971) lists the following, in descending order of toxicity:
Within a genus, there seems to be little difference in the toxicity of species. Thus, the genera reported to cause or suspected of causing hay fever are listed here.
Betula spp. Among the most important trees producing allergenic pollen (Service, 1934).
Broussonetia spp. An important cause of spring hay fever and pollen asthma, particularly in Arizona (Balyeat and Rinkel, 1932; Bernton, 1928).
Carya spp. Responsible for a number of cases of spring hay fever in the US Middle Atlantic states (Brown, 1932).
Celtis spp. The most important cause of hay fever in Argentina (Carron and Malvarez, 1941; Walker and Carron, 1940).
Cupressus spp. Responsible for most cases of winter-spring hay fever in South Africa. C. arizonica causes some hay fever in Arizona (Ordman, 1945, 1947; Wodehouse, 1971).
Juglans spp. California black walnut is the most common cause of spring hay fever in the Sacramento, Napa and Russian river valleys in California (Hall, 1918).
Juniperus spp. J. mexicana causes a serious winter hay fever in Texas (Kahn and Grothaus, 1931).
Platanus spp. Cause hay fever in the US Middle Atlantic states and California (Brown, 1932; Hall, 1922).
Populus spp. Commonly cause hay-fever allergies (Johnson, 1938).
Prosopis spp. Responsible for much, very severe hay fever in southwest regions of the United States; important in South Africa, Hawaii and Mexico (Larsen and Weller 1945; Ordman, 1959; Sellers, 1929).
Quercus spp. Major contributors to spring hay fever (Chamberlain, 1927).
Acacia spp. Not important since they are primarily insect-pollinated. Pollen in small quantities is extremely toxic (Hall, 1922; Rowe, 1931).
Acer spp. The role of maples in hay fever is not clear. Early spring hay fever (in Manitoba) has been attributed to A. negundo (Walton and Dudley, 1947).
Ailanthus spp. Cause hay fever in China, the United States and Jerusalem (Blumstein, 1943; Tas, 1956).
Carpinus spp. A contributing factor in birch hay fever (Wodehouse, 1971).
Casuarina spp. Some hay-fever cases reported in southern Florida (Wodehouse, 1971; Zivits, 1951).
Chamaecyparis spp. C. Iawsoniana pollen is a contrite. using factor in Texas hay fever (Black, 1929).
Fagus spp. Minor contributors to hay fever (Wodehouse, 1965).
Frazinus spp. Among the most abundant pollen caught on pollen slides, but cases caused directly by ash are rare (Chamberlain, 1927; Duke and Durham, 1928).
Maclara spp. Occasionally a serious cause of hay fever (Bernton, 1928).
Myrica spp. A contributing cause of winter hay fever in Bermuda (Gay, Curtis and Norris, 1941).
Pinus spp. Infrequently associated with hay fever (Boggs, 1946).
Salix spp. Of minor or incidental importance (Chamber lain, 1927).
Tilia spp. Although trees are insect-pollinated, hay-fever cases have been reported (Derbes, 1941).
Gingko spp. (Wodehouse, 1971); palms (Davison, Lowance and Durham, 1934); Prunus spp. (Wodehouse 1965); Pyrus spp. (Wodehouse, 1965); Tsuga spp. (Wodehouse, 1965).
TESTING THE POLLEN COUNT hay-fever borne on the breeze (CHARLES L. WILSON)
The most important study of skin tests for tree pollen allergies was conducted in Sweden (Eriksson, 1978). Pollen from 12 different deciduous trees was used, and the reactions of the greatest intensity were to birch, alder, bog myrtle, beech and hazel allergens. Oak, aspen, linden, elm, willow, maple and poplar allergens gave negative or weakly positive reactions. It was concluded that for diagnostic screening the birch pollen allergen alone it was sufficient. It was suggested that therapeutic programmes In western Sweden should contain birch, aider, hazed, beech and bogmyrtle allergens.
Recent studies have suggested the usefulness of kelotifer and DSCG for tree-pollen-induced childhood asthma (Giraff-Lonnevig and Kusoffsky, 1980). These studies also report on the effect of ketotifan and sodium cromoglycate in children with pollen-induced asthma.
In selecting trees for urban environments, little or no attention has bean given to the allergenic toxicity of tree pollen. With the present concern over air pollution and improving air quality, such consideration seems in order. New housing developments offer the unique opportunity to control atmospheric pollen through tree selection. In estatablished urban areas, tree pollen may be modified through tree management and replanting practices.
It is also possible that progress in tree breeding and selection could develop male-sterile trees that do not produce pollen. This has been accomplished in a number of crop-breeding programmes.
Cooperation between allergy specialists and arboricuiturists is needed in order to develop recommendations for tree plantings with reduced allergenic pollen. The only place where the allergist and the arboriculturist get together now is the doctor's office. They need to get together in the laboratory, because much more research is needed for effective control of tree-pollen pollution. The antiquity of the references in this article demonstrates the lack of recent research in this area.
BALYEAT, R.M. & RINKEL, H.J. 1983 Distribution and importance of the paper mulberry as the cause of hay-fever and asthma in the United States. J. Allergy, 3: 7-15.
BERNTON, H.S. 1928 Hayfever and asthma caused by the pollen of the paper mulberry. I. Lab. and Clin. Med., 13: 829.
BLACK, J.H. 1929 Cedar hayfever. J. Allergy, 1: 71-73.
BLACK, J. H. & DURHAM, O.C. 1930 Elm pollen as a complicating factor in hayfever, J. Allergy, 1: 501 -505.
BLUMSTEIN, G.I. 1943 Sensitivity to Ailanthus pollen. J. Allergy, 14: 329-334.
BOGGS, H.W. 1946 A case of early spring hayfever apparently due to pine pollen. Internat. Correspond. Club of Allergy, 10:20.
BROWN, G.T. 1932 Seasonal hayfever with special reference to the Middle Atlantic states. J. Med. Soc. N. J. 24: 438-490.
CARRON, R.F. & MALVAREZ, H.E. 1941 Polinosis por tale (Celtis tala), reacciones sistemáticas y costitucionales. Prensa Méd. Argent., 21 May: 1114.
CHAMBERLAIN, C.T. 1927 Observations on the treatment of hayfever in the Pacific Northwest. Ann. Otol., Rhinol., and Laryngol., 36: 1083-1092.
DAVISON, H.M., LOWANCE, M.I. & DURHAM, O.C. 1934 The principal hayfever plants and pollens of the South. South. Med. J., 27: 529-535.
DERBES, V.J. 1941 The linden (Tilia) as a factor in seasonal pollinosis. J. Allergy, 12: 502.
DUKE, W.W. & DURHAM, O.C. 1928 Pollen content of still air. J. Amer. Med. Assoc., 90: 1529-1532.
DURHAM, O.C. 1949 Air-borne allergens in national parks. J. Allergy, 20: 255-268.
ERIKSSON, N.E. 1978 Allergy to pollen from different deciduous trees in Sweden. An investigation with skin tests, provocation tests and the radioallergosorbent test (RAST) in springtime hay fever patients. Allergy 33: 299-309.
GAY, L.N., CURTIS, H. & NORRIS, T. 1941 A pollen survey of the island of Bermuda. Bull. Johns Hopkins Hosp., 68:179.
GOTTLIEB, P.M. & URBACH, E. 1943 The distribution and pollination times of the important hayfever-producing-plants in the United States. J. Lab. and Clin. Med., 28: 1053.
GRAFF-LONNEVIG, V. & KUSOFFSKY, E. 1980 Comparison of the clinical effect of ketotifen and DSCG in pollen-induced childhood asthma. Allergy, 35: 341-348.
GRAFF-LONNEVIG, V & KUSOFFSKY, E. 1980 A comparative study of the prophylactic effect of ketotifen and sodium cromoglycate in children with pollen-induced asthma. Schweiz. Med. Wochenschr., 110: 195-196.
HAIL, H.M. 1918 Walnut pollen as a cause of hayfever. Science, 68: 516-517.
HALL, H.M. 1922 Hayfever plants of California. US Pub. Health Repts, 37: 803-822.
HYDE, H.A. 1956 Tree pollen in Great Britain. Acta Allergol., 10: 224-245.
JOHNSON, R.P. 1938 The specific treatment of hayfever and pollen asthma in Denver. Rocky Mt. Med. J., 5: 305.
KAHN, I.S. & GROTHAUS, E.M. 1930 Tree pollen hayfever and asthma in the South. Sth. Med. J., 23: 662-665.
KAHN, I.S. & GROTHAUS, E.M. 1931 Hayfever and asthma due to red cedar and to mountain cedar. Sth. Med. J., 24: 729-730.
KESSLER, A. 1958 Sensitivity to olive pollen (olea europaea) as the cause of allergic diseases. Dapim Refuilm, 17:3.
KEY, S.M. 1918 The etiology of winter hayfever in Texas. Texas State J. Med., 1 3: 308-309.
LARSEN, N. & WELLER, D.M. 1945 Atopy. Plantation Health (Honolulu), 9: 22-26.
ORDMAN, D. 1945 Cypress pollinosis in South Africa: a study of the seasonal hayfever and allergic conjunctivitis occurring in the winter-spring period. S. Africa Med. J., 19:142.
ORDMAN, D. 1947 Pollinosis in South Africa. S. Africa Med. J., 21:3848.
ORDMAN, D. 1959 The Prosopis tree as a cause of seasonal hayfever and asthma in southwest Africa and South Africa. S. Africa Med. J., 33:12.
ROWE, A.H. 1931 Botanical survey of San Joaquin County in central California. J. Allergy, 3: 98.
SCHEPPEGRELL, W. 1925 Tree pollen hayfever. New Orleans Med. and Surg. J., 78: 132-136.
SELLERS, E.D. 1929 Mesquite tree pollen as a cause of hayfever. Tex. State J. Med., 25: 297-299.
SERVICE, W.C. 1934 Hayfever of Pikes Peak region. Colo. Med., 31: 311-313.
TAS, J. 1956 Ailanthus glandulosa pollen as a cause of hayfever. Ann. Allergy, 14: 47.
THOMMEN, A.A. 1930 Hayfever: the spring type. Med. J. and Rec., 131: 496.
TUFT, L. & BLUMSTEIN, G.L. 1937 Incidence and importance of tree pollen hayfever with particular reference to Philadelphia and vicinity. J. Allergy, 8:464.
WALKER, H. & CARRON, R.F. 1940 A contribution to the study of pollinosis in the Argentine Republic. A new plant allergen, Celtis tala. Diag. Med., 6: 104-141.
WALTON, C.H.A. & DUDLEY, M. 1947 A geographical study of hayfever plants in Manitoba. Can. Med. Assoc. J., 56: 142-148.
WARING, J.J. & POPE, M. 1927 The cotton of the cottonwood tree, a factor in hayfever. Colo. Med., July 1927.
WILLIS, A.H. & DEGLER, H.E. 1939 Air conditioning for the relief of cedar-pollen hayfever. University of Texas pub. no. 3932.
WODEHOUSE, R.P. 1965 Pollen grains. New York, Hafner Press. 574p.
WODEHOUSE, R.P. 1971 Hayfever plants. New York, Hafner Press. 280 p.
ZIVITS, N. 1942 Allergy to Australian pine (Cosuarina). J. Allergy, 13: 314-316.
ZIVITS, N. 1951 The effect of the Miami (Florida) climate on imported allergic problems. J. Allergy, 22: 524.
FAO Training Series 2
A manual prepared by FAO and ILO, this complete illustrated guide to the use of chainsaws in the tropics was published in 1980. Available in English, French and Spanish.
FAO, Distribution and Sales Section Via delle Terme di Caracalla