Allergen Update
Brandon, Manitoba
Predominant pollen:
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.- Maple trees- There is an early short season in early April. The main season can start from mid to late April and end early to late May and lasts approximately three weeks with some high counts. The difference in seasons from year to year is due to the effect of weather and the spring temperatures.
Alnus sp.- Alder fluctuates from low to moderate counts throughout the season due to the number of species and the effects of weather. The season is from late March to mid-June.
Quercus sp.- Oak is considered to be an important allergen. There are two distinct seasons; one at the end of April to the beginning of May, and lasts about one week with moderate counts. The second season has high counts, can occur from mid-May to mid-June, and lasts approximately three weeks.
Betula sp.- Birch season can vary by as much as a month. Counts can be in the very high range. The season can start between the end of April to late May and can end from mid-May to early June.
Corylus sp.- The hazelnuts have a season lasting approximately two to three weeks and moderate counts are observed. Pollination can occur from early April to mid-May.
Pinaceae group- This group includes the pine, spruce and firs. Some very high counts are observed and the season can start from early to late May and end from early June to early July. This is a month difference in when the season can occur. This is very important to those who have allergies to this group of trees.
Cupressaceae group- The cedars, junipers and yews produce very sporadic counts with moderate and high counts occuring during the month of April to early May. The season fluctuates due to the effect of weather. Probably of no significance in causing allergic reactions.
Populus sp.- Poplar and aspen season is from late April to early May but can occur as late as late May and last up to early June. There are some very high counts, which may cause allergic reactions to individuals who are highly sensitized.
Fraxinus sp.- Ash do produce some very high counts and may be significant allergens. The season lasts about two weeks and the time of pollination can fluctuate due to weather. The season can start late April to late May and end early May to early June.
Ulmus sp.- The elm are considered important allergens. There is short early season that lasts about one week and it can occur late March to early April. The main season lasts approximately two weeks, with some very high counts, and can occur from mid-April to mid-May. The season fluctuates a great deal from year to year due to the effect of weather.
Salix sp.- The willows produce mostly moderate counts with a few high counts. The season lasts approximately five weeks and can occur from mid-April to early June. The fluctuation in the season is due to the effect of weather. May only cause allergic reactions in highly sensitized individuals.
Gramineae- The grasses produce significant counts in June and July. The counts are mostly in the moderate range, with a few high counts, during this period. The season starts with low counts around mid-May.
Ambrosia sp.- Ragweed season begins mid-July and ends well into October. Moderate counts are observed from the second week of August to mid-September.
Urtica sp.- Nettles occur in significant numbers that may cause allergic reactions. The season is from late June to the end of August with some moderate counts.
Artemisia sp.- The sagebrushes and mugworts can cause allergic reactions. The season, with significant counts in the moderate range, occurs in August and September.
Chenopodiaceae & Amaranthaceae- This group of weeds are similar microscopically and are not differentiated. They include some weeds which are considered highly allergenic. The counts are mostly in the moderate range, with the occasional high, from late July to early September.
Predominant spores:
Diatrypaceae sp.- The counts are sporadic with some very high counts. The season is from late March to early October.
Leptosphaeria sp. & Leptosphaeria look-alikes- These two are grouped together since they are in the same class of fungi and are similar microscopically. The heaviest counts are observed from May to the end of September with great fluctuations in counts from day to day. This is probably due to the effect of weather. Very high counts are observed. Could be significant in causing allergic reactions.
Erysephe (Oospora)- Powdery mildew - The season is from mid-April to mid-October. The counts are sporadic. May not cause allergic reactions.
Boletus sp.- The counts for this spore do get high and may be of significance in causing allergic reactions. The season is July to the end of September with the highest counts observed in August.
Coprinus sp.- This mushroom can produce very high counts from mid-May to mid-October. Can be an important allergen.
Ganoderma sp.- This bracket fungus can produce high counts from June to the end of September. Can be a significant allergen.
Uredinales- The rusts do produce very high counts but not enough is known about their significance in causing allergic reactions. The main season is from June to mid-October.
Ustilaginales- The smuts can reach very high counts, and allergenicity is unknown. The season is May to mid-October.
Alternaria sp.- The season happens from April to mid-October. Very high counts are observed from mid-June to mid-October. Some species are known to cause allergic reactions. It may be an important allergen.
Penicillium & Aspergillus sp.- These spores are found throughout the whole counting season and are probably present in significant numbers beyond that. High counts are observed throughout the whole season, from March to mid-October.
Botrytis sp.- This may be a significant allergen although the counts do not get very high. The season is sporadic from late May to the end of September.
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 March to well into late fall.
Epicoccum sp.- Some species are known to cause allergic reactions. The season with significant counts is from July to mid-October and some high counts are observed.
Fusarium sp.- Counts are very sporadic throughout the whole counting season. The majority of the season occurs from mid-May to the end of September with some high counts. This fungus is well known to cause food spoilage, reactions when the toxin is ingested and other allergic reactions.
Helicomyces sp.- Season is from late May to the end of September producing moderate and high counts. The season is very sporadic.
Pithomyces sp.- Season is mostly in the low to moderate range and the highest counts are observed from the end of July to mid-October.
Torula sp.- Can cause allergic reactions. The season with significant counts, in the low to moderate ranges, is from the end of June to mid-October with mostly moderate counts.
Stemphylium sp.- The season is from mid-July to the end of September with spore counts in the low to moderate range.
Drechslera sp.- The counts are never very high. This is a summer and fall spore. There are other related genera, which are also found in air samples, that can cause respiratory problems. One example is Bipolaris sp.
Myxomycetes- Moderate and high counts are observed from May to mid-October. Allergenic properties are not well understood.
Last Updated: 03-March-2006
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