Thunder Bay, Ontario
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.
Acer sp.- The maples 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.
Alnus sp.- The 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.
Betula sp.- The start and end of the 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.
Birch look-a-likes sp.-The Birch look-alike season can be sporadic or it can last up to three weeks.
Corylus sp.- The 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.
Populus sp.- The poplar, cottonwood 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.
Cupressaceae family- The 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).
Fraxinus sp.- The 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.
Pinaceae family- This includes the spruce, fir and pine trees. Very high counts are observed 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.
Quercus sp.- The 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.
Salix sp.- The 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.
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.
Ulmus sp.- The elms 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.
Gramineae family- The 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.
Artemisia sp.- The sagebrush and mugwort season is from late July to early October with only low counts observed. Could be considered an important allergen in highly sensitized individuals.
Ambrosia sp.- 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.
Urticaceae sp.- The 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.
Plantago sp.- The plantains 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.
Chenopodiaceae & Amaranthaceae- 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.
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.
Diatrypaceae sp.- The counts are sporadic throughout the whole counting season. High counts can be observed from March to well into October. No known allergic properties.
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, 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. The Leptoshpaeria-look-alikes produce sporadic moderate and very high counts from May to mid-October.
Erysiphe (Oospora) sp.- Powdery mildew - The season is from mid-April to mid-October. Very high counts are observed. Allergenic properties are unkown.
Venturia sp.- This 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.
Boletus sp.- The counts for this spore do get very high and may be significant in causing allergic reactions. The season is mid-June to mid-October.
Coprinus sp.- This mushroom can produce some very high counts from May through to mid-October. It is considered an important allergen.
Ganoderma sp.- This bracket fungus can produce very high counts from mid-June to mid-October. It is considered an important allergen.
Uredinales sp.- The 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.- The smuts can reach high counts, allergenicity is unknown. The season with significant counts is mid-May to mid-October with some high counts.
Alternaria sp.- Some high counts are observed and certain species are known to cause allergic reactions. The season with significant counts is from May to mid-October.
Penicillium sp. and 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 March to well into October.
Botrytis sp.- This 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.
Cladosporium sp.- This 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.
Epicoccum sp.- Some species are known to cause allergic reactions. The main season is from May to mid-October with low to moderate counts.
Fusarium sp.- Counts are very sporadic from April to mid-October. Some high counts are observed.
Helicomyces sp.- The main season is very sporadic from May to the end of September producing moderate and very high counts.
Polythrincium sp.- The 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.
Pithomyces sp.- Season is mostly in the low to moderate range from mid-June to mid-October.
Caloplaca sp.- Sporadic counts are observed from March to mid-October. The allergenicity of this fungal spore is not well understood.
Myxomycetes- Moderate and high counts are observed from April to mid-October.
Last Updated: 3 Mach 2015
The information presented here is designed to inform, not replace, the relationship that exists between a patient and a medical professional.