Predominant Pollen and Spores

Alder season can start from mid-March to early April and end from the first to the last week of June. The counts, most years, are in the low to moderate ranges. Some years high counts are possible. They are considered important allergens and, at these levels, can cause allergic reactions in sensitized individuals.

Ash season can start from the first to the third week of April and end the third week of May to early June. High counts are observed and they are considered to be allergenic in highly sensitized individuals.

Beech season can vary a great deal from year to year. This is due to a combination of the effect of weather and cyclical patterns. The season can start from mid-April to mid-May and end the third week of May to early June. The season can be sporadic but some years moderate counts are observed. They can cause allergic reactiond in highly sensitized individuals.

Birch season can start from the second to the last week of April and end early to mid-June. Some very high counts are observed and they are considered important allergens. The birch look-a-likes’ season can vary a great deal from year to year. The counts can be only in the low range and some years the counts get high. The season is mostly in May and some species are considered allergenic.

Cedars, junipers and yews produce low to high counts. The season can start from early or mid-March to late March and end early to mid-June. Most species in Canada are not considered allergenic.

Chestnuts are important allergens. The season varies from year to year with usually only low counts observed. Some years moderate counts are possible. The season can start from the second week of May to early June and end mid to late June.

Elm are important allergens. The season can start mid-March to mid-April and end late April to mid-June. The counts can reach high levels.

Grasses produce moderate to high pollen counts from the third week of May to the third week of July. The season starts early to late May and ends late September to early October.

Hazelnut season can start the third week of March to early April and end the third week of April to early May. Mostly low counts are observed. At these levels they would only cause allegic reactions in highly sensitized individuals.

Hemlock season can start from early to late May and end late May to mid-June. The season can be sporadic and varies from year to year. The counts can be in the moderate range. May cause allergic reactions in individuals who are highly sensitized when shed in high numbers.

Hickory season can vary a great deal from year to year. This is partially due to the effect of weather and also to annual cycles. The season can start from late April to mid-May and end mid to late June. Some years moderate counts are observed. They could cause allergic reactions in highly sensitized individuals.

Linden and basswood season varies from year to year. The season can start from the third week of June to the first week of July and end mid to late July. Some years hardly and pollen is produced whereas other years low and moderate counts are observed. May cause allergic reactions in those individuals who are highly sensitized.

Maple season varies due to the number of species present and the effect of weather. Significant counts, in the moderate and high range, can be observed from the last week of March to late May. The season can start from mid to late March and end mid-May to early June. Some species are considered allergenic.

Mulberry season can start from mid-April to early May and end early to mid-June. Low and moderate counts (rare high counts possible) are observed. They can cause allergic reactions at these levels.

Nettles and parietaria occur in significant numbers that may cause allergic reactions. The season can start from mid-May to mid-June and end from the third to the last week of September. The counts can reach moderate levels. They are considered important allergens due to their small size.

Oak season can start from the second week of April to mid-May and end early to mid-June. The seasons can be highly affected by weather. The counts do get very high. Some species are known to cause allergic reactions.

Spruce, fir and pine season can begin mid-April to late May and end early to late July. The counts do get very high and they are important allergens to those who have allergies to this group.

Plantains are important allergens. Low to moderate counts occur at this location. The season can start from early to mid-June and end late September to mid-October. They are considered important allergens even at low levels.

Poplar, cottonwood and aspen season starts from mid-March to early April and ends early to late May. The counts get very high and may cause allergic reactions.

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.

Walnut season can start from early May to early June and end late May to the third week of June. Low and moderate counts are observed at this site. They can cause allergic reactions in highly sensitized individuals.

Willow season can start from early to late April and end third week of May to early June. Certain years the counts can get in the high range. They may cause allergic reactions.

Alternaria counts do get high and some species are known to cause allergic reactions. The season is from April to mid-October. The highest counts occur from June to mid-October.

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.

Boletus 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 from June to mid-October.

Botrytis may be a significant allergen although the counts do not get very high. The season is from May to the end of September.

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 mid-April to mid-October. It is considered an important allergen.

Diatrypaceae counts are sporadic throughout the whole counting season. High counts can be observed from late March to mid-October.

Some species of epicoccum are known to cause allergic reactions and the season, with moderate and high counts, is from June to mid-October.

Erysiphe, also know as powdery mildew, season is from mid-April to mid-October. Low to high counts are observed.

Fusarium counts are very sporadic throughout the whole counting season. The majority of the season occurs from May to mid-October with some high counts. Can cause allergic reactions.

Ganoderma or bracket fungus can produce very high counts from June to mid-October. It is considered an important allergen.

Helicomyces season is from May to the end of September producing moderate and high counts. The season is very sporadic.

The season for leptosphaeria is mid-May to mid-September with great fluctuations in counts from day to day. This is probably due to the effect of weather. Moderate and high counts are observed from April to mid-October.

Moderate counts are observed from June to late September.

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.

Pithomyces season is mostly in the low to moderate range from June to mid-October.

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

Some species of torula are known to cause allergic reactions. Moderate counts are observed from June to mid-October. The season is sporadic.

Uredinales also know as rusts do occur in really high numbers in the late summer but not enough is known about their significance in causing allergic reactions at these levels. The season is from early May to late October.

Ustilaginales or smuts can reach high counts, allergenicity is unknown. The season is mid-April to mid-October with some high counts.