Allergen Update
Toronto, Ontario (Queen's Park region)
Predominant pollen:
The tree pollen seasons can fluctuate from year to year by as much as two to three weeks at this site. The pollen seasons described here try to cover the time when each can occur.
Acer sp.- Maple season varies due to the number of species present and the effect of weather. Significant counts, in the moderate and high range, are observed from the end of March to mid-May.
Alnus sp.- Alder season occurs from April to early June and the counts vary from low to moderate. The fluctuation in the season is due to the number of species present and the effect of weather.
Betula sp.- The birch season can occur from mid-April to early June with some very high counts observed. The birch look-a-likes' season has significant counts for approximately four weeks and can occur from mid-April to early June.
Populus sp.- The poplar and aspen season is from late March to mid-May. The occasional count is high and may cause allergic reactions.
Carya- The hickories pollinate for approximately two weeks and the season can occur from early May to late June with some moderate counts observed.
Castenea- The chestnuts are important allergens. The season lasts approximately two weeks and it can occur from mid-May to late June. The Horse Chestnut, which is the most allergenic, is found only in low numbers. The season can occur from mid-May to mid-June.
Cupressaceae group- The cedars, junipers and yews produce moderate and high counts from the end of March to the end of May.
Fraxinus sp.- The ash pollination season is April to late May. High counts are observed and they are considered to be allergenic only in highly sensitized individuals.
Pinaceae group- This group includes the spruce, fir and pine trees. High counts are observed from May to late June. The time of the season can vary from year to year by as much as two weeks.
Quercus sp.- The oaks have two distinct seasons. The first pollination is short and occurs from mid to late April. The main season, which produces the most pollen, occurs mostly from May to early June. The oaks are considered to be highly allergenic.
Ulmus sp.- The elm are important allergens. The season lasts approximately two to three weeks and can occur from late March to late April with low to high counts observed.
Salix- The willow season is from mid-April to late May with low and moderate counts.
Morus- Mulberry season lasts approximately four weeks and can occur from late April to mid-June. Moderate and high counts are observed.
Gramineae- The grasses produce significant pollen counts from the end of May to the end of July. The season starts early May and lasts until the end of September.
Ambrosia sp.- Ragweed pollen is observed from mid-July until mid to late October with the highest counts occurring the second week of August to late September.
Urtica sp.- Nettles only occur in low numbers and may not cause allergic reactions at these levels. The season is June to mid-September.
Predominant spores:
Diatrypaceae sp.- The counts are sporadic throughout the whole counting season. High counts can be observed from late March to mid-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 late March to late October with great fluctuations in counts from day to day. This is probably due to the effect of weather. Moderate and very high counts are observed from mid-May to late October.
Erysephe (Oospora)- Powdery mildew - The season is from late April to mid-October. Low and high counts are observed.
Boletus sp.- The season for this spore is very sporadic with some very high counts observed. It may be of significance in causing allergic reactions. The season is June to mid-October.
Coprinus sp.- This mushroom can produce some moderate and high counts from late April to late October. It is considered an important allergen.
Ganoderma sp.- This bracket fungus can produce very high counts from June to late October. It is considered an important allergen.
Uredinales- The rusts do not occur in really high numbers and not enough is known about their significance in causing allergic reactions at these levels. The season is from June to late October.
Ustilaginales- The smuts can reach high counts in the fall, and allergenicity is unknown. The season, with low and moderate counts, is May to well into November.
Alternaria sp.- The counts do get high and some species are known to cause allergic reactions. The season is from May to early November.
Penicillium & Aspergillus sp.- These spores are found throughout the whole counting season and are probably present in significant numbers beyond that. High counts are observed from mid-March to late fall.
Botrytis sp.- This may be a significant allergen although the counts do not get high. The season is June to mid-October.
Cladosporium sp.- The most abundant spore found throughout the whole season. This spore exists all year round but very high counts are known to occur from March to well into late fall.
Epicoccum sp.- Some species are known to cause allergic reactions. The season is from May to late fall with some high counts observed.
Fusarium sp.- Counts are very sporadic throughout the whole counting season. The majority of the season occurs from May to mid-October with low to moderate counts observed.
Helicomyces sp.- Season is from mid-April to the end of September producing moderate and high counts. The season is sporadic.
Pithomyces sp.- Season is mostly in the low range from July to the end of September. May not cause allergic reactions at these levels.
Polythrincium sp.- Allergenicity is unknown but significant counts are observed from August to the end of September.
Torula sp.- Some species are known to cause allergic reactions. The occasional moderate counts are observed from June to early October. Season is sporadic.
Myxomycetes- Low to occasional high counts are observed from June to early October.
Last Updated: 03-April-2006
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