Allergen Update
Ottawa, Ontario
Predominant pollen:
The tree pollen seasons can fluctuate from year to year by as much as two to three weeks at this site due to the effect of weather. The pollen seasons described here try to cover the time when each can occur.
Acer sp.- Maple season flutuates due to the number of species present and the effect of weather. Significant counts can be observed from April to the late May.
Alnus sp.- Alder season occurs from late March to mid-June and the counts vary from low to high due to the number of species present. The seasons vary from year to year in counts and when the season occurs due to the effect of weather.
Betula sp.- The birch season is mostly in May and high counts are observed. The start and end of the season can vary from year to year by as much as two weeks based on the effect of weather. Birch look-a-likes' season occurs in May and the counts are in the moderate and high ranges.
Populus sp.- The poplar and aspen season can occur from late March to mid-May. The counts are moderate to high and may cause allergic reactions.
Cupressaceae group- The cedars, junipers, and yews produce high counts from the end of March through April. The season start and end dates can fluctuate from year to year by as much as two to three weeks, this is due to the effect of weather.
Fraxinus sp.- The ash pollination season is mid-April to the end of May and lasts approximately four weeks. Some high counts are observed. The start and end of the season can vary by two weeks depending on weather.
Pinaceae group- High counts are observed throughout the pollen season. The start of pollination can begin from the second week of May to late May and can end between the beginning to the end of June. The pollen may cause reactions in highly sensitized individuals.
Quercus sp.- The oaks flower for a short season late April, the main season occurring mostly from May to early June. Moderate to high counts are observed. There can be a variation of two weeks from year to year in the start and end dates of the season which is due to the effect of weather. Some of the oak species are considered highly allergenic.
Carya- The hickories pollinate for almost two weeks and the season can occur from early May to late June with some moderate counts.
Tsuga sp.- The hemlocks pollen season can occur from mid-May to early June for approximately two weeks. The occasional moderate count is observed.
Fagus sp.- Moderate and low counts can be observed fom mid-May to early June. They may not cause reactions except in highly sensitized individuals.
Salix sp.- The willows may cause allergies to highly sensitized individuals. Moderate counts are observed from mid-April to late May.
Ulmus sp.- The elm are important allergens. The season is highly affected by weather and pollination can occur from mid to late April with the occasional moderate counts observed. There is also an early season that lasts about one week late March to early April.
Morus- Mulberry season lasts approximately two to three weeks. It can occur from early to late May, and moderate counts are observed. Can be considered allergenic in idividuals who are highly sensitized.
Gramineae- The grasses produce significant counts from mid-May to the end of July. The season starts early May and lasts well into September.
Ambrosia sp.- Ragweed pollen is observed starting the last two weeks of July with the high counts occurring from August to late September. Low pollen counts are observed until late October.
Urtica sp.- Nettles occur in significant numbers that may cause allergic reactions. The season is from late June to mid-September.
Plantago sp.- The plantains can be of significance in causing allergic reactions. The season is from mid-June to late September with only low counts observed.
Predominant spores:
Diatrypaceae sp.- The spore counts are sporadic throughout the whole counting season. High counts can be observed from March to well into October.
Leptosphaeria sp. & Leptosphaeria look-a-likes- These two are grouped together since they are in the same class of fungi and are similar microscopically. The season is May to mid-October with great fluctuations in counts from day to day. This is probably due to the effect of weather. The counts are in the moderate and high range. The look-alikes produce some very high counts.
Erysephe (Oospora)- Powdery mildew - The season, with moderate and high counts, occurs from April to mid-October.
Caloplaca sp.- Moderate counts are observed from August to mid-October. The season is sporadic. May not be an important allergen.
Boletus sp.- The counts for this spore do not get very high but may be of significance in causing allergic reactions. The season is sporadic and occurs from mid-June to mid-October.
Coprinus sp.- This mushroom can produce moderate and high counts from early May to late October. Considered an important allergen.
Ganoderma sp.- This bracket fungus can produce very high counts from June to late October. Considered an important allergen.
Uredinales- The rusts do not occur in really high numbers, but not enough is known about their significance in causing allergic reactions at these levels. The season is from mid-May to late October.
Ustilaginales- The smuts can reach high counts, allergenicity is unknown. The season is mid-May to late October.
Alternaria sp.- Some of the counts are really high throughout the season and some species are known to cause allergic reactions. The season is from March to late October. The highest counts occur from late May to late October.
Penicillium & Aspergillus sp.- These spores are found throughout the whole counting season and are probably present in significant numbers beyond that. The moderate and high counts are observed from late March to late fall.
Botrytis sp.- This may be a significant allergen even though the counts do not get very high. The season is from late May to mid-October.
Cladosporium sp.- The most abundant spore found throughout the whole season. This spore exists all year round and very high counts are known to occur from March to late fall.
Epicoccum sp.- Found in high numbers and some species are known to cause allergic reactions. The season is from March to late fall. The high counts occur from mid-June to late October.
Fusarium sp.- Counts are very sporadic throughout the whole counting season. The season occurs from March to mid-October.
Helicomyces sp.- Season is from May to mid-October producing moderate and high counts. The season is very sporadic.
Pithomyces sp.- Season with high to low counts is from July to mid-October.
Torula sp.- Some species are considered allergenic. Moderate counts are observed from July to early October.
Polythrincium sp.- Allergenicity is unknown but significant counts are observed from July to mid-October.
Myxomycetes- Moderate counts are observed from August to mid-October.
Last Updated: 10-March-2006
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