Predominant Pollen and Spores

Alder season can start mid to late March and end from the first early to mid-June. 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.

Ash pollen season can start as ealry as the third week of March during warm years. It generally starts early to late April and ends mid to late May. High counts are observed and they could cause allergic reactions in sensitized individuals

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.

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 late April to the second week of May. May cause allergic reactions in individuals who are highly sensitized.

Birch season can start from the first to the last week of April and end early to late June. High counts are observed most years. They are considered important allergens.

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.

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.

Elm has a short early season late February to early March. The main season can start second week of March in a warm year, but generally the season starts from the third week of March to early April and ends mid-April to mid-May. Some years very high counts are possible. At these levels they could cause allergic reactions.

Grass season can start, with low counts, as early as mid-April to early May and end early to mid-October. Moderate and high counts are observed from the third week of May to the third week of July .

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.

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 occasional moderate possible.

Horse Chestnut, which is the most allergenic of all chestnuts, 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.

Linden 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.

Maple and Box Elder 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 the first to last 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.

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 as early as mid-April in a warm year, but generally the season starts from late April to second week of May and ends late May to mid-June.

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.

Oak season is highly affected by weather. The season can start as early as the last week of March in a warm year, but generally it startsfrom the second to last week of April and ends from the end of May to the second week of June. High counts are observed. Some species are known to cause allergic reactions.

Moderate and high counts are observed from May to late June for the pine, fir and spruce. The time of the season can vary from year to year by as much as three weeks. The season can start as early as mid-April in a warm year, but generally it starts from the first to the second week of May and ends late June to mid-July.

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.

Poplar, cottonwood and aspen season can start as early as mid-March in a warm year, but generally it starts from late March to mid-April and ends early to mid-May. High counts are observed and at these levels they can cause allergic reactions.

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.

Walnut season can start from the first to the third week of May and end early to mid-June. The season can vary from year to year. Most years low and moderate counts are observed.

Willow season can start form the first to the third week of April and end from early to late May. Low and moderate counts are observed.

Aspergillus 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.

The season for the Boletus 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.

Botrytis may be a significant allergen although the counts do not get high. The season is June to mid-October.

Cladosporium is 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.

Coprinus – Mushroom can produce some moderate and high counts from late April to late October. It is considered an important allergen.

Counts for Diatrypaceae are sporadic throughout the whole counting season. High counts can be observed from late March to mid-October. They are not known to cause allergic reactions.

Some species of Epicoccum are known to cause allergic reactions. The season is from May to late fall with some high counts observed.

The season for Erysiphe also known as Powdery mildew is from late April to mid-October. Low and high counts are observed.

Counts for Fusarium 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.

Ganoderma also known as Bracket fungus can produce very high counts from June to late October. It is considered an important allergen.

Helicomyces season is from mid-April to the end of September producing moderate and high counts. The season is sporadic.

The season for Leptosphaeria 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.

Low to occasional high counts are observed from June to early October.

Pithomyces season is mostly in the low range from July to the end of September. May not cause allergic reactions at these levels.

Penicillium 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.

Allergenicity is unknown but significant counts are observed from August to the end of September.

Some species of Torula are known to cause allergic reactions. The occasional moderate counts are observed from June to early October. Season is sporadic.

Uredinales a.k.a 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 a.k.a 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.