Predominant Pollen and Spores

Alder season can begin mid to late March and end mid to late June. Low and moderate, with an occasional high, counts are observed. At these levels allergic reactions could occur.

Ash season can start early April during warm years but generally starts from mid to late April and ends the late May to early June. Very high counts are observed. Allergic reactions could occur in sensitized individuals.

Beech season can vary from year to year not only on when the season can occur but also in how much pollen is produced. Some years the counts are low and sporadic whereas other years occasional moderate counts are observed. The season can start early to mid-May and ends mid to late May.

Birch season can start early April in warm years like 2010 and 2012. Generally the start is from the third week to final week of April and ends late May to early June. Very high counts are observed. They are considered important allergens.

Cedar, juniper, and yew season can start early to late March and end late May to mid-June. Very high counts are observed. Most of the species in Canada are not considered allergenic.

Chestnut season can start the third week of May to early June and end mid to late June. The season can vary from year to year and the occasional moderate count is observed.

Elm are important allergens. The season can start early to late March, depending on the weather, and ends late April to early May with the occational moderate and high counts observed.

Grasses produce moderate and high counts from late May to late July. The season can start late April to the third week of May and end mid-October.

Hemlock season can vary from year to year in how much pollen can be produced and season length. This is due to the effect of weather and cyclical patterns of the species.

The season can start from the second to the third week of May and end the first to the third week of July. Some years moderate counts are observed whereas other years only sporadic low counts are captured on our sampler.

Hickory season can start from the second to last week of May and end mid to late June. The season varies from year to year. Most years low and moderate counts are observed.

Linden and basswood season varies a great deal from year to year. Some years moderate counts are observed whereas other years only rare sporadic low counts are captured. The season can start late June to early July and end mid to late July.

Maple season fluctuates due to the number of species present and the effect of weather. The season can start as early as the second week of March during warm years like 2010 and 2012. Generally the start is from late March to the first week of April and the end is from the third to the last week of May. High counts are observed and some species can create allergic reactions.

Mulberry season can last well over a month. The season can start from late April to early May and end early to mid-June. The counts are in the low to moderate range. They can be considered allergenic in individuals who are highly sensitized.

Nettles and parietaria are considered important in causing allergic reactions due to their small size. The season can start mid-June and end about the third week of September. The counts are in the low to moderate range.

Oak season can start from the second to the third week of April and ends early to mid-June. The counts can get very high. Some species are considered allergenic.

High counts are observed for pine, fir and spruce throughout the pollen season. The season can start from about mid-April to the second week of May and end early to late July. High counts are observed. May cause reactions in highly sensitized individuals.

Plantains produce mostly low counts. The season can start from the third to the last week of May and end early October. Even at these levels, allergic reactions can occur in sensitized individuals.

Poplar, cottonwood, and aspen season can start the 2nd to third week of March in warm years like 2010 and 2012. Generally the season starts from the the last week of March to the second week of April and ends from the first to the last week of May. The counts vary from low to high and may cause allergic reactions.

Ragweed pollen can be observed throughout much of with low counts. Moderate and high counts occur from August to late September. Low pollen counts are observed until well into October or until a hard frost occurs.

Walnut season can start from early to mid-May and end the first to the third week of June. Some years the counts can get moderate but mostly low counts are observed. The seasons vary from year to year based on weather and possible cyclical patterns.

Willows may cause allergic reactions in highly sensitized individuals. Low and moderate counts are usually observed, but rare high counts are possible.

The season can start as early as the third week of March to the first week of April in warm years like 2010 and 2012. Generally the season start is from mid to late April and ends mid to late May.

Some species of alternaria are known to cause allergic reactions. The season is from May to mid-October with the highest counts occuring July to Mid-October.

Aspergillus spores are found throughout the whole counting season and are probably present in significant numbers beyond that period. Significant counts are observed from March to late fall.

Botrytis may be a significant allergen even though the counts do not get very high. The highest counts occur from June to mid-October.

Boletus counts for this spore do get high but significance in causing allergic reactions is not well understood. The main season is mid-July to mid-October.

Moderate counts of caloplaca are observed from early April to mid-October. The season is sporadic. May not be an important allergen.

Cladosporium is the most abundant spore found throughout the whole season. This spore exists all year round and very high counts are known to occur from March to late fall.

Coprinus mushroom can produce moderate and high counts from early May to mid-October. Considered an important allergen.

Diatrypaceae 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.

Epicoccum is not found in really high numbers but some species are known to cause allergic reactions. Season is from May to mid-October.

Erysiphe, also know as powdery mildew, season is from early April to mid-October. Low to high counts are observed throughout the season.

Fusarium counts are very sporadic throughout the whole counting season. The majority of the season occurs from May to mid-October.

Ganoderma or bracket fungus can produce very high counts from June to mid-October. Considered an important allergen.

Helicomyces season is from May to mid-October producing moderate and high counts. The season is very sporadic.

Leptosphaeria season is May to mid-October with great fluctuations in counts from day to day. This is probably due to the effect of weather. The counts are in the moderate and high range. The look-alikes produce some very high counts.

Moderate counts of Myxomycetes are observed from August to mid-October. Allergenic properties are unknown.

Penicillium spores are found throughout the whole counting season and are probably present in significant numbers beyond that period. Significant counts are observed from March to late fall.

Pithomyces season is mostly in the moderate range from July to mid-October.

Allergenicity of polythrincium is unknown but significant counts are observed from late June to early October.

Some species of torula are considered allergenic. Moderate counts are observed from June to early October.

Uredinales or rusts do not occur in really high numbers and not enough is known if they are of significance in causing allergic reactions at these levels. The season with significant counts is from June to mid-October.

Ustilaginales also know as smuts can reach high counts. Allergenicity is unknown. The season is May to mid-October.