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Predominant Pollen and Spores

Thunder Bay, Ontario

Tree pollen and spore seasons fluctuate from year to year by as much as two to four weeks at this site due to the effect of weather. The pollen and spore seasons described here are generalizations as to when pollination/sporulation occurs.

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Predominant Pollen for Thunder Bay

Due to extreme variations in the weather at this site, the tree pollen season fluctuates significantly from year to year. The pollen seasons described here try to cover the time when each can occur.

Alder (Alnus sp.)
Alder season, with significant counts, can start from late March to mid-April and end early to late June. The counts fluctuate from low to very high due to the number of species present and the effect of weather. Considered to be important allergens.
Amaranthaceae & Chenopodiaceae

This group of weeds are similar microscopically and are not differentiated. They include some weeds, which are considered allergenic. Mostly low with the occasional moderate counts are observed. The season can start from late June to the third week of July and end middle to late September. This group contains a few species that are considered allergenic.

Ash (Fraxinus sp.)
Ash pollination season lasts between two to four weeks. The season can start from the third week of April to mid-May and end mid-May to the second week of June. The season fluctuates a great deal from year to year and the counts can range from low to high depending on the weather. Considered to be allergenic only in highly sensitized individuals.
Birch (Betula sp.)
Birch season can fluctuate a great deal due to the effect of weather. The season can start late April to mid-May and end late May to late June. The counts can be very high and can play an important role in allergic reactions.
Cedars, Junipers and Yew (Cupressaceae family)
Cedars, junipers and yews produce low to very high counts. The season can start from mid to late March and end early to mid-June. May only be of significance in individuals who are highly sensitized. (Most species in Canada do not cause allergic reactions).
Elm (Ulmus sp.)
Elm can have a short early season from mid-March to early April. The main season can occur from the second week of April to early May and end early to mid-May. The season varies a great deal from year to year not only on when it occurs but also on how much pollen is released in the atmosphere. Counts vary from very low to some years obtaining moderate counts. They could play a role in causing allergic reactions in individuals who are highly sensitized.
Grasses (Gramineae family)
Grasses produce moderate and high counts in June and July. The season can start the second week of May to early June and end early October.
Hazel (Corylus sp.)
Hazelnuts have a season lasting approximately two to three weeks and occasional moderate and high counts are observed. The season can start from early April to almost the end of April and end early May to about mid-May.
Larch (Larix sp.)

The season for the larch and tamaracks can vary a gret deal from year to year. Some years hardly any pollen is produced, yet other years moderate counts can be obtained. The season can start from mid-April to early May and end early to late May.

Maple (Acer sp.)
With maple trees can have a shorter early season with low counts which can occur late March to early April. The main season can start from mid-April to early May and end mid-May to early June. Seasons vary in duration, timing and pollen levels from year to year mostly due to the effects of weather. Some species are known to cause allergic reactions.
Mugwort (Artemisia sp.)
Mugworts season is from late July to early October with only low counts observed. Could be considered an important allergen in highly sensitized individuals.
Nettles (Urticaceae sp.)
Nettles and parietaria season can start from mid-June to early July and end early to late September. The counts are mostly in the low range. They play an important role in causing allergic reactions in highly sensitized individuals, especially due to their small size.
Oak (Quercus sp.)
Oak season can start from late April to late May. The season can end the third week of May to mid-June. The seasons can vary a lot from year to year. Some species are considered allergenic.
Pine, fir and spruce (Pinaceae family)
Very high counts are observed for pine, fir and spruce. and the season can start from early to late May and end early to late July. This group can be very important to those who have allergic sensitivities.
Plantains (Plantago sp.)
Plantain pollinate from July to the end of September with mostly low and occassional moderate counts. They may cause allergic reactions in highly sensitized individuals even at low levels.
Poplar, cottonwood and aspen (Populus sp.)
Poplar and aspen season can start from early April to the fourth week of April and can end early to late May. Some of the counts can get very high and may cause allergic reactions.
Ragweed (Ambrosia sp.)
Low counts of ragweed pollen is observed from late July to mid-October. Some moderate and occasional high counts are observed from the third week of August to mid-September. The end of the season occurs with a hard frost.
Sagebrush (Artemisia sp.)
Low counts of Sagebrushes season is from late July to early October with only low counts observed. Could be considered an important allergen in highly sensitized individuals.
Willow (Salix sp.)
Willows season varies a great deal from year to year. The season can start from mid-April to mid-May and end late May to mid-June.

Predominant Spores for Thunder Bay

Spore seasons fluctuate from year to year by as much as two to four weeks at this site due to the effect of weather. Spores described here are generalizations as to when sporulation occurs.

Note: This site is unique because during the late summer months (July to September) the predominant group of spores include the Basidiomycota. This group consists of many fungal spores and some are known to be highly allergenic.

Alternaria sp.
Alternaria are observed and certain species are known to cause allergic reactions. The season with significant counts is from May to mid-October.
Aspergillus sp.
Aspergillus spores are found throughout the whole counting season and are probably present in significant numbers beyond that. The highest counts are observed from March to well into October.
Boletus sp.
Boletus counts for this spore do get very high and may be significant in causing allergic reactions. The season is mid-June to mid-October.
Botrytis sp.
Botrytis may be a significant allergen and the counts do get very high. The season is from May to early October with moderate and some high counts.
Caloplaca sp.

Sporadic counts of Caloplaca are observed from March to mid-October. The allergenicity of this fungal spore is not well understood.

Cladosporium sp.
Cladosporium spore is found throughout the whole season and exists all year round. Very high counts are known to occur from late March to well into October.
Coprinus sp.
Coprinus mushroom can produce some very high counts from May through to mid-October. It is considered an important allergen.
Diatrypaceae sp.
Diatrypaceae counts are sporadic throughout the whole counting season. High counts can be observed from March to well into October. No known allergic properties.
Epicoccum sp.
Some species of epicoccum are known to cause allergic reactions. The main season is from May to mid-October with low to moderate counts.
Erysiphe (Oospora) sp.
Erysiphe, also known as Powdery mildew, season is from mid-April to mid-October. Very high counts are observed. Allergenic properties are unkown.
Fusarium sp.
Fusarium counts are very sporadic from April to mid-October. Some high counts are observed.
Ganoderma sp.
Ganoderma or bracket fungus can produce very high counts from mid-June to mid-October. It is considered an important allergen.
Helicomyces sp.
The main season for Helicomyces is very sporadic from May to the end of September producing moderate and very high counts.
Leptosphaeria sp.
The heaviest counts of Leptosphaeria season, with significant counts, is May to early October, with great fluctuations in counts from day to day, which is probably due to the effect of weather. Very high counts are observed from May to early October.
Myxomycetes

Moderate and high counts of Myxomycetes are observed from April to mid-October.

Penicillium sp.
Penicillium spores are found throughout the whole counting season and are probably present in significant numbers beyond that. The highest counts are observed from March to well into October.
Pithomyces sp.
Pithomyces is mostly in the low to moderate range from mid-June to mid-October.
Polythrincium sp.

Polythrincium season is from mid-June to the end of September with low to high counts observed. The allergenicity of this fungal spore is not well understood.

Uredinales sp.
Uredinales or rusts do sometimes occur in really high numbers but not enough is known about their significance in causing allergic reactions at these levels. The season is from the end of May to mid-October.
Ustilaginales sp.
Ustilaginales a.k.a smuts can reach high counts, allergenicity is unknown. The season with significant counts is mid-May to mid-October with some high counts.
Venturia sp.

Venturia spore is very abundant at this site and the season is sporadic producing some very high counts from mid-May to mid-October. Allergenic properties are not well understood but it is mostly associated with apple scab.

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