Allergen Update

London, Ontario

Predominant pollen:

The tree pollen seasons can fluctuate from year to year by as much as two to four weeks at this site. The pollen seasons described here try to cover the time when each can occur.

Acer sp.- The maples have an early that can occur from about the second to third week of March. The main season can start from the third week of March to the end of March and end mid to late May. Low to high counts are observed. Certain species are known to cause allergic reactions.

Alnus sp.- Alder season can start from mid to late March and end late June. The counts fluctuate from low to moderate with an occasional high possible. The season is highly affected by the weather. They can be considered important allergens at these levesl.

Betula sp.- The birch season can start from the first to the last week of April and end mid-May to early June. The timing of the season varies from year to year as well as the amount of pollen produced. The pollen lavels can reach moderae or high levels depending on the year. They are considered important allergens. Birch look-a-likes' season lasts two to four weeks and can occur from mid-April to about mid-May and the counts are mostly in the low to moderate range.

Corylus sp.- The hazelnut season can last two to three weeks. The season can start from mid-March to early April and end late April to early May. Only low counts are observed. They can cause allergic reactions in individuals who are highly sensitized.

Castenea sp.- The chestnuts are important allergens and the season lasts from two to five weeks. The season can start from early to late May and end mid to late June. The Horse Chestnut, which is the most allergenic, is found in low to moderate numbers for approximately one to two weekd. The season can occur from mid-May to mid-June.

Juglans sp.- The walnuts are considered important in causing allergic reactions. The pollen season can start from early May to mid-May and can end late May to late June. Very high counts are observed at this site.

Carya sp.- The hickories have a short season which usually occurs late April and only has low counts. The main season can start early to the third week of May and end mid to late June. The pollen levels can vary from year to year and moderate counts can be observed. The season can last well over a month.

Populus sp.- The poplars, cottonwoods and aspens can have a very short season mid-March. The main season can last almost two months and can start late Marh to early April and end early to late May. Some of the counts are very high and may cause allergic reactions.

Fagus sp.- The beech season varies from year to year. Some years we get only sporadic and low counts and other years the season can last well over a month with low and moderate counts. This fluctuation is due to natural cycles and weather. The season can start from mid-April to early May and end mid-May to early June. May cause allergic reactions in individuals who are highly sensitized.

Cupressaceae family- The cedars, junipers, and yews produce low to high counts and the season varies a great deal from year to year. The season can start from early to late March and end late May to mid-June.>

Fraxinus sp.- The ash pollen season lasts well over a month. The season can start early to almost the end of April and end mid-May to early June. Some very high counts are observed and they are considered to be allergenic in highly sensitized individuals.

Pinaceae family- This includes the spruce, fir and pine trees. Some high counts are observed and the season can vary by as much as a month. The season can start from mid-April to early May and end early to late July.

Quercus sp.- The oaks have several flowering periods which is due to the many species present. The seasons are affected by weather conditions. The season can start from the first to the last week of April and end late May to almost mid-June. The counts can get very high. Some of the species are considered highly allergenic.

Salix sp.- The pollen season lasts well over a month. The season can start the third week of March to the third week of April and end late May to early June. Pollen levels can vary from year to year. Most years low and some moderate counts are observed. Other years the occasional high count is obtained. They can cause allergic reactions in individuals who are highly sensitized.

Ulmus sp.- The elm are considered important allergens. The season can start early to mid-March and some years early April. The season end is from late April to early May. The timing of the season and the amount of pollen produced each year varies a great deal and this is partly due to the effect of weather. Mostly low to moderate counts are obtained. High counts can be observed some years.

Morus sp.- The mulberries produce very high counts at this site. The pollen season lasts approximately six weeks due to the many species present at this site. The season can start mid-April to early May and end early to late June. They are considered important allergens in high numbers.

Gramineae family- The grass season is from late April to October. Moderate and high counts are observed from May to late July.

Ambrosia sp.- Ragweed pollen can be observed from early July. The season usually starts late July and ends well into October when a heavy frost occurs. Moderate and high counts are obtained from the first week of August to early October. They are considered important allergens.

Urticaceae sp.- Nettles and parietaria pollinate from late May to late September and moderate counts are observed from mid-July and into August. They are considered important allergen partly due to their small size and ability to get into the lungs.

Plantago sp.- The plantains pollinate from June to early October. The counts are generally in the low range and occasionally moderate. This may cause allergic reaction in highly sensitized individuals.

Predominant spores:

Diatrypaceae sp.- The counts are sporadic throughout the whole counting season. High counts can be observed from March to well into 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 season is May to early October with fluctuations in counts from day to day which is probably due to the effect of weather. Highest counts are observed from June to the end of September.

Erysiphe (Oospora) sp.- Powdery mildew - The season is from May to mid-October. Mostly moderate counts are observed.

Boletus sp.- The counts for this spore do get high and may be significant in causing allergic reactions. The season is July to mid-October.

Coprinus sp.- This mushroom can produce some very high counts from May to late October. It is considered an important allergen.

Ganoderma sp.- The bracket fungus can produce very high counts from July to mid-October. During the months of May and June the counts are moderate to high. It is considered an important allergen.

Uredinales sp.- The rusts do not occur in really high numbers and allergenic properties are not well understood. The season is from June to late October.

Ustilaginales sp.- The smuts can reach high counts, allergenicity is unknown. The season is May to mid-October. Very high counts are observed in September and October.

Alternaria sp.- Some high counts are observed and certain species are known to cause allergic reactions. The season is from May to the end of September.

Penicillium sp. & 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 July to well into October.

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 May to late October.

Epicoccum sp.- Some species are known to cause allergic reactions. The season is from June to mid-October with some high counts.

Fusarium sp.- Counts are very sporadic from June to mid-October. Majority of highest counts are observed in late summer and fall.

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

Torula sp.- Moderate counts are observed in September and October.

Polythrincium sp.- Moderate counts are observed mid-August to the end of September.

Pithomyces sp.- Moderate counts are observed late July to early October.

Myxomycetes- Moderate counts are observed from June to late September.

Last Updated : 28 July 2009

The information presented here is designed to inform, not replace, the relationship that exists between a patient and a medical professional.

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