Allergen Update
Montreal, Quebec (lasalle region)
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 varies due to the number of species and the effect of weather. Significant counts can be observed from late March to mid-May. There is an early short season, weather permitting, late March to early April. The main season can occur from April to mid-May depending on the weather conditions. Certain species are considered important in causing allergic reactions.
Alnus sp.- Alder season occurs from late March to mid-June and fluctuates greatly from year to year. The counts range from low to high due to the various species present.
Betula sp.- The birch season is mostly in May but can start mid-April and end mid-June. High counts are observed and they are considered important in causing allergic reactions. Birch look-a-likes'season is mostly in May. Low to moderate counts are observed.
Populus sp.- The poplar and aspen season is from late March to mid-May and the start and end dates can vary by as much at two to three weeks. The counts are high and may cause allergic reactions.
Carya- The hickories pollinate for almost two weeks and the season can occur from mid-May to late June with some moderate counts.
Castanea/Aesculus sp.- The chestnuts pollinate for two to three weeks and the season can occur from late May to mid-June. Some of the species are considered highly allergenic. Moderate and high counts are observed.
Cupressaceae group- The cedars, junipers, and yews produce low to high counts from late March to mid-May. There is a great variation in the start and end dates from year to year due to the effect of weather.
Fraxinus sp.- The ash pollination season can occur from mid-April to the end of May, depending on weather, with low to high counts.
Fagus sp.- The beech season is from early May to the end of May. It may not cause allergic reactions except for those individuals who are highly sensitized.
Pinaceae group- High counts are observed and the season start and end dates can vary by as much as a month due to the effect of weather. The season start can be from early to late May and the season end from mid-June to early July. These are important allergens to those who have allergies to this group of trees.
Quercus sp.- The oaks have a short early flowering season which can occur from mid-April to early May. The main season, where low to high counts are observed, lasts about three weeks and can occur from early May to early June. They are considered to be of importance in causing allergic reactions.
Salix sp.- The willows main pollen season can occur from mid-April to late May and the counts are very sporadic ranging from low to moderate. They may not cause allergic reactions except in individuals who are highly sensitized.
Tsuga sp.- The hemlocks pollen season can occur from mid-May to early June and some moderate counts can be observed.
Ulmus sp.- The elm are important allergens. The pollen seasons can vary by two weeks for the start and end dates. There is a short early season which lasts about one week from late March to early April. The main season lasts one to two weeks in April with the occasional moderate and high counts. The elm season is highly affected by weather.
Gramineae- The grass season is from mid-May to early October. Moderate and high counts are observed the latter part of May to mid-July but this can vary by as much as two weeks. Grass has another small season with significant counts in early September. This late species is unique to areas along the Saint Lawrence River.
Ambrosia sp.- Ragweed pollen is observed late July with the high counts occurring from August to mid-September. Low pollen counts are observed until late October.
Urtica sp.- Nettles occur in significant numbers that may cause allergic reactions and the main season is June to August.
Plantago sp.- The plantains can be of significance in causing allergic reactions. The season is from mid-June to early October with only low counts observed.
Predominant spores:
Diatrypaceae sp.- The 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 April to late October with great fluctuations in counts from day to day. This is probably due to the effect of weather. The significant counts are mostly in the moderate range.
Erysephe (Oospora)- Powdery mildew - The season is from mid-April to mid-October. Significant counts are mostly in the moderate range.
Caloplaca sp.- Moderate counts occur from the end of August to mid-October. The season is sporadic and it may cause allergic reactions.
Coprinus sp.- This mushroom can produce high counts from 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 and not enough is known about their significance in causing allergic reactions at these levels. The main season is from June to late October.
Ustilaginales- The smuts can reach high counts, but allergenicity is unknown. The season is May to late October.
Alternaria sp.- The counts can get really high and some species are known to cause allergic reactions. The main season is from 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. Significant counts are observed from March to late fall.
Boletus sp.- The counts for this spore do not get very high but may be of significance in causing allergic reactions. The main season is June to mid-October.
Botrytis sp.- This may be a significant allergen even though the counts do not get very high. The season is July, August and September.
Cladosporium sp.- The most abundant spore found throughout the whole season. This spore exists all year round but the highest counts occur from March to late fall.
Epicoccum sp.- Not found in really high numbers but some species are known to cause allergic reactions. Season is July to late fall.
Fusarium sp.- Counts are very sporadic throughout the whole counting season. The majority of the season occurs from mid-June to mid-October.
Helicomyces sp.- Majority of season is from May to the end of September.
Pithomyces sp.- The main season is August and September.
Polythrincium sp.- Allergenicity is unknown but significant counts are observed from the end of July to the end of September.
Myxomycetes- Moderate counts are observed from March to September.
Last Updated: 10-March-2006
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