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.- The maples have more than one season because of the number of species present at this site. The first season, which lasts approximately one and a half weeks, can occur from mid-February to early March with generally only low counts observed. This season may not occur or may be missed due to how early it occurs. The main season can start mid to late March and ends early to late May or early June. Significant counts can be observed ranging from low to high. The seasons vary from year to year not only for the timing but for the amount of pollen produced. Some species are known to cause allergic reactions.
Alnus sp.- Alder season occurs from late February to mid-June. The counts fluctuate mostly from low to moderate. Occasionally high counts occur during the early season. The alder season is highly affected by weather. They can be significant in causing allergic reactions.
Betula sp.- The birch season can begin from the first to third week of April and end around mid-May to early June. Generally the counts are low and moderate. Rare high counts can occur. The timing of the season can vary from year to year as well as the amount of pollen produced. They are considered important allergens.
Birch look-a-likes sp.- The birch look-a-likes have two distinct seasons, with low to high counts, each lasting at least two weeks and they can occur between early April to the second week of May.
Juglans sp.- The walnut season lasts approximately a month. The season can occur from early May to mid-May and end the firs to third week of June. The beginning of the season can be sporadic. Low and moderate counts are observed.
Castenea sp.- The chestnuts are important allergens and the season lasts approximately four weeks. The season can start from the second to the fourth week of May and end mid-June to early July. The Horse Chestnut, which is the most allergenic, is only found in low numbers.
Carya sp.- The hickories have a short early season towads the end of April. The main season can last almost a month. The season can start early May to late May and end early to late June. Some moderate counts can be observed in the main season.
Populus sp.- The poplar, cottonwoods and aspen season is very dependent on weather conditions. An early season can occur late February to early March, if the weather conditions are favourable. The main season can start from early March to early April and end early to late May. The timing of the season as well as the amount of pollen produced is highly affected by weather. The counts can reach the high range and may cause allergic reactions.
Cupressaceae family- The cedars, junipers and yews can produce low to high counts from about mid-February to early June. The season is very sporadic due to the number of species present and the effect of weather.
Fraxinus sp.- The ash pollen season can last approximately up to six weeks and can start from the end of March to late April and end mid-May to early June. The counts range from low to high throughout the season and they are considered to be allergenic in highly sensitized individuals.
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 mid-May and end mid to late May. May cause allergic reactions in individuals who are highly sensitized.
Pinaceae family- This group includes the pine, spruce and firs and the season fluctuates a great deal due to the effect of weather and the number of species present. The season can start from late March to late April and end early to mid-June. High counts are observed and can be of significance to those individuals who suffer from allergies to this group.
Quercus sp.- The oak season, in warm years like 2012, can start late March. Gererally the season starts early early to late April and end from mid-May to mid-June. The seasons can vary a great deal from year to year which is mostly attributable to weather conditions. The counts can reach very high levels and certain species are highly allergenic.
Ulmus sp.- The elm season can last about four to five weeks with an early season that occurs late February to early March with low and the occasional moderate counts possible. The main season can begin from mid-March to early April and end mid to late April. The types of seasons that occur every year is partially dependant on weather. The counts can get high with mostly low and moderate counts observed through the season. The elms are important allergens in individuals who are sensitized.
Salix sp.- The willows have a long season that lasts almost two months. The season starts from late March to mid-April and can end from mid-May to almost mid-June. The counts vary from low to moderate throughout the season. There are several species and they cause allergic reactions in individuals who are highly sensitized.
Morus sp.- Mulberry season can last from four to five weeks. The season can start from mid-April to mid-May and end late May to mid-June. There are many species found at this site and the counts can be very high. They can cause allergic reactions in individuals who are highly sensitized.
Gramineae family- The grasses produce moderate to high counts from mid-May to mid-July. The season starts from mid to late April and ends around mid-October, depending on the season. There is another peak with moderate counts early September. This species is unique to certain sites (Montreal being another location). The grass season starts late April and lasts until late October.
Ambrosia sp.- Ragweed pollen occurs mid-July to well into October. Low counts can be observed early July. The season is mostly from mid-July to well into October. Moderate and high counts can occur from August to mid-October.
Urticaceae sp.- The nettles and parietaria occur in significant numbers that may cause allergic reactions and are important, especially due to their small size. The season usually starts from the second week of May to late May and ends late September.
Plantago sp.- The plantains are important allergens. Moderate and high counts occur at this location. The season can start late May to mid-June and end late September. They are considered important allergens even at low levels. (see pollen definitions for details)
Diatrypaceae sp.- The counts are sporadic throughout the whole counting season. High counts can be observed from March to well into October. They are not known to cause allergic reactions.
Leptosphaeria sp. and 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 mid-October with great fluctuations in counts from day to day. This is probably due to the effect of weather. Very high counts occur in the months of May to early October.
Erysiphe (Oospora) sp.- Powdery mildew - The season with the highest counts is from May to mid-October. Mostly moderate counts are observed.
Boletus sp.- The counts for this mushroom spore do get high and may be of significance in causing allergic reactions. The season is early June to mid-October.
Coprinus sp.- This mushroom can produce very high counts from late April to mid-October. It is considered an important allergen.
Ganoderma sp.- The bracket fungus can produce very high spore counts from mid-May to mid-October. It is considered an important allergen.
Uredinales sp.- The rusts can occur in really high numbers but not enough is known about their significance in causing allergic reactions at these levels. The main season is from mid-May to late October.
Ustilaginales sp.- The smuts can reach high counts, and allergenicity is unknown. The main season is late April to mid-October with some high counts.
Alternaria sp.- The counts do get high and some species are known to cause allergic reactions. The season, with significant counts, is from early April to the end of October.
Penicillium sp. & Aspergillus sp.- These spores are found throughout the whole counting season and are probably present in significant numbers beyond that. The highest counts are observed from mid-March to late fall.
Botrytis sp.- This may be a significant allergen although the counts do not get very high. The season is May to early 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 mid-February to well into November.
Epicoccum sp.- Some species are known to cause allergic reactions. The season is from March to the end of October with some high counts from August to early October.
Fusarium sp.- Counts are very sporadic throughout the whole counting season. The majority of the season occurs from April to mid-October with some high counts.
Helicomyces sp.- The season, with high counts, is from May to the end of September. The season is very sporadic.
Pithomyces sp.- Season is mostly in the low to moderate range from June to mid-October.
Polythrincium sp.- Allergenicity is unknown but significant counts are observed from the end of May to the end of September.
Torula sp.- Some species are known to cause allergic reactions. Moderate and some high counts are observed from late June to mid-October. Season is sporadic.
Myxomycetes- Moderate counts are observed from late April to mid-October.
Last Updated: 3 March 2015
The information presented here is designed to inform, not replace, the relationship that exists between a patient and a medical professional.