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. The counts do get very high, particularly from mid to late April. The main season can start from the second to the last week of March and end third week of May to early June. There is a short early season that can occur late Feruary to early March. Some species are known to cause allergic reactions.
Alnus sp.- Alder season can start mid to late March and end from the first week of June to the first week of July. There is a short season with low counts possible in January. Most years the counts are in the low to moderate range, although some years high counts are possible. The fluctuation in the season is due to the number of species present and the effect of weather. Can cause allergic reactions at these levels.
Betula sp.- The birch season can start from the second to the third week of April and end the last week of May to the second week of June. High counts are observed most years. They are considered important allergens. The birch look-a-likes' season usually occurs late April and parts of May. Moderate counts are observed and some species may cause allergic reactions.
Corylus sp.- The hazelnut season can start mid-March to early April and end late April to early May. Only low counts are observed.
Populus sp.- The poplar, cottonwood and aspen season can start from late March to early April and end early to mid-May. High counts are observed and at these levels they can cause allergic reactions.
Carya sp.- The hickory season lasts two to four weeks and can start the third week in April to early May and end from the second to the last week of June. Mostly low counts are observed with the occational moderate possible.
Juglans sp.- The walnut season can start early to mid-May and end early to late June. The season can vary from year to year. Most years low and moderate counts are observed.
Tsuga sp.- The hemlock season can vary a great deal from year to year. This is probably due to the effect of weather and cyclical patterns. Most years only produce low counts but moderate counts are possible. The season can start from early to late May and end late May to mid-June.
Castenea sp.- The chestnuts are important allergens. Mostly low counts are observed but certain years occasional moderate counts are possible. The season lasts approximately two to four weeks, depending on the year, and it can start from the third week of May to the first week of June and end the third week of June to the first week of July. The Horse Chestnut, which is the most allergenic, is found only in low numbers. The season can start from the second to the third week of May and end the second to third week of June.
Cupressaceae family- The season for the cedars, junipers and yews can start late February to early March and end early to mid-June. Some years very high counts are observed. Most species found in Canada are not known to cause allergic reactions.
Fraxinus sp.- The ash pollen season can start the second to the third week of April and end late May to early June. High counts are observed and they could cause allergic reactions in sensitized individuals.
Tilia sp.- The linden and basswood season varies from year to year due to weather and possible cyclical patterns. Most years only low counts are observed. The season can start the second to last week of June and end the second to last week of July.
Fagus sp.- The beech, some years, produce moderate counts and other years hardly any pollen is observed. The season varies a great deal from year to year due to the effect of weather and possible cycles for this species. The season can start from mid-April to early May and end the third week of May to early June. May cause allergic reactions in individuals who are highly sensitized.
Pinaceae family- This group includes the spruce, fir and pine trees. Moderate and high counts are observed from May to late June. The time of the season can vary from year to year by as much as three weeks. The season can start mid-April to early May and end late June to late July.
Quercus sp.- The oak season is highly affected by weather. The season can start mid to late April and end the first to the second week of June. High counts are observed. Some species are known to cause allergic reactions.
Ulmus sp.- The elm has a short early season late February to early March. The main season can start from the second to the last week of March and end late April to mid-May. Some years very high counts are possible. At these levels they could cause allergic reactions.
Salix sp.- The willow season can start mid to late April and end mid to late May. Low and moderate counts are observed.
Morus sp.- The mulberry season can last over two months. The counts do get very high and they play an important role in causing allergic reactions at these levels. The season can start from mid-April to early May and end the first to the third week of June.
Gramineae family- The grass season can start late April to early May and end early to mid-October. Moderate and high counts are observed.
Ambrosia sp.- Ragweed season can start from from the first to the third week of July and end late October, or with a hard frost. The highest counts occurring the second week of August to the third week of September.
Urticaceae sp.- The nettles and parietaria are considered important allergens due to their small size. The season can start late May and end late September. Mostly low counts are observed with rare moderate counts possible.
Plantago sp.- The plantains can be important allergens. Only low counts are observed at this location. Even at these levels they can cause reactions in highly sensitized individuals. The season can start early to mid-June and end late 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-alikes- 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.
Erysiphe (Oospora) sp.- 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 sp.- 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 sp.- 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 sp. & 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 : 21 July 2009
The information presented here is designed to inform, not replace, the relationship that exists between a patient and a medical professional.
