Allergen Update

Hamilton, 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 maple season can start from early to the third week of March and end between mid to late May. Moderate and high counts are observed. Certain species are known to cause allergic reactions.

Alnus sp.- Alder season can start from early March to early April and end late May to mid-June. There are fluctuations in the counts from low to moderate (Some years an occational high count is possible). The season is highly affected by weather. At these levels they can cause allergic reactions in individuals who are highly sensitized.

Betula sp.- The birch season can start from the second to the last week of April and end late May to early June with counts ranging from low to high. The counts do get very high and they are considered important allergens.

Birch look-a-like sp.- The birch-look-a-like season can last from one week to a month and can occur from mid-April to about late May and the counts are in the low to moderate range. Some species are considered allergenic.

Castanea sp.- The season for the chestnuts can start mid to late May and end mid to late June. Mostly low with the occasional moderate counts are observed.

Carya sp.- The hickories have a short early season, lasting approximately one week from late April to early May. The main season can last almost a month and can start from mid to late May and end mid to late June. Most of the counts are low but some years an occational moderate count is possible.

Juglans sp.- The walnuts are considered important in causing allergic reactions. The pollen season can start early May to mid-May and can end the third week of June. The counts can get very high at this site.

Tsuga sp.- The hemlocks have very different seasons from year to year. This is due to weather and probably natural cycles. The season usually only produces low counts but moderate counts are possible. The season can start early to mid-May and ends late May to mid-June.

Populus sp.- The poplar, cottonwood and aspen season can start from late March to early April and end the second to third week of May. The season can last almost six weeks and high counts are observed. At these levels they can cause allergic reactions.

Fagus sp.- The beech season varies a great deal from year to year. Some years the season lasts well over month, while other years hardly any counts are observed. This is partly due to weather, but also caused by the natural cycles for these trees. The counts are mostly low with the occational moderate count possible in some years. The season can start the third week of April to the first week of May and end mid to late May. 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 occur from late February to late June. The counts do get very high. Most species in Canada are not considered allergenic.

Fraxinus sp.- The ash pollen season lasts well over four weeks. The season can start from about mid to late April and end late May. Some low to high counts are observed and they are considered to be allergenic only in highly sensitized individuals.

Pinaceae family- This includes the spruce, fir and pine trees. Some high counts are observed and the occurence of the pollen season can vary from year to year. The season can start from the second week of April to the first week of May and can end early to mid-July. Significant allergens for individuals who are sensitized.

Quercus sp.- The oaks have several flowering periods due to the number of species present. The season can start the second to last week of April and ends the first to second week of June. Some of the counts are very high. The season is affected by weather as to when it starts and the amount of pollen released. Some of the species are considered allergenic.

Salix sp.- The pollen season lasts for more than one month and can start from early to mid April and end mid to late May. The counts are usually low to moderate, but occationally a high count is observed. They are considered to be allergenic only in highly sensitized individuals.

Tilia sp.- The linden and basswood season can start mid-June to early July and end mid to late July. Most years the counts are in the low range, but an occational moderate count can occur. They may not be of any significance at these levels.

Ulmus sp.- The elms are considered important allergens. The season can start from early to mid-Marh and ends around early May. The whole season can last almost two months. Some high counts are observed.

Morus sp.- The mulberries produce very high counts at this site due to the number of species present. The pollen season can last approximately two months. The season starts from mid to late April and ends early to mid-June. Can be a significant allergen for those individuals who are sensitized.

Gramineae family- The grass season can start as early as late April and end early October. Low to high counts are observed from the end of May to late July.

Ambrosia sp.- Ragweed pollen is observed from late July to late October. Moderate to high counts are obtained in August and September.

Urticaceae sp.- The nettles and parietaria pollinate from June to late September and low to moderate counts are observed from mid-July to late August. They are considered important allergens due to their small size.

Plantago sp.- The plantains pollinate from June to early October. The counts are generally in the low range and occasionally moderate. They may cause allergic reactions 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. They are not known to cause allergic reactions.

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 May to the end of September.

Erysiphe (Oospora) sp.- Powdery mildew - The season is from April to mid-October. Low to high counts are observed. Allergenic properties are not well understood.

Boletus sp.- The counts for this mushroom 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.- This bracket fungus can produce very high counts from June to late October. 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, and their allergenicity is unknown. The season is from May to late 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 mid-April to the end of October with the highest counts occuring from June to October.

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 June to well into October.

Cladosporium sp.- The most abundant spore found throughout the whole season. This spore exists all year round but the highest counts occur from May to late October. Some species are known to cause allergic reactions.

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

Fusarium sp.- Counts are sporadic throughout the whole counting season. The majority of the highest counts are observed from May to late September.

Helicomyces sp.- Season is from April to mid-September producing moderate and very high counts. The season is very sporadic.

Torula sp.- Moderate counts are observed from July to September.

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

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

Myxomycetes- Few moderate counts are observed from June to late September.

Last Updated : 3-March-2015

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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