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 a short early short season that may occur from late March to mid-April. The main season can start from mid to late April and end mid-May to early June. The difference in seasons from year to year is due to the effect of weather and the spring temperatures.
Alnus sp.- Alder fluctuates, most years, from low to moderate counts throughout the season due to the number of species and the effect of weather. Rare high counts can occur. The season can start from late March to mid-May and end the first week of June to the end of June.
Betula sp.- Birch season can vary by as much as a month. Counts can be in the very high range. The season can start from mid-April to mid-May and end late May to mid-June.
Corylus sp.- The hazelnuts have a season lasting approximately two to three weeks and moderate counts can be observed. The pollen season can start from early to late April and end late April to mid-May.
Pinaceae family- This group includes the pine, spruce and firs. Some very high counts can be observed. The season can start from early to mid-May and ends early to late July. There is a month's difference in when the season can occur. This group is very important to those who have allergies to these trees.
Cupressaceae family- 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 can start mid to late March and end early to mid-June. The season fluctuates due to the effect of weather. May not be of significance in causing allergic reactions.
Populus sp.- Poplar, cottonwood and aspen season can start from early to mid-April and ends early to late May. 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 can last up to a month and the time of the pollen season can fluctuate due to weather. The season can start mid-April to mid-May and end mid-May to early June. Most years the counts do get high with many low and moderate counts observed.
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 mostly low counts (moderate counts are possible). The second season has high counts and can occur from early May to early June lasting approximately three weeks ending from late May to the third week of June. Some of the oaks are considered important allergens.
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 mid-April. The main season lasts approximately two weeks, with some very high counts, and can occur from mid to late April and end early to late May. The season fluctuates a great deal from year to year due to the effect of weather.
Salix sp.- The willows produce mostly low and moderate counts with the occational high count, depending on the year. The season can last four to five weeks. Season start is from mid-April to early May and ends late May to almost mid-June. The fluctuation in the season is due to the effect of weather. May only cause allergic reactions in highly sensitized individuals.
Gramineae family- 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 from mid-May to early June and ends mid-October.
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.
Urticaceae sp.- Parietaria and nettles occur in significant numbers and they are considered important allergens. The season is from mid to late June and ends early to mid-September.
Artemisia sp.- The sagebrushes and mugworts can cause allergic reactions. The main season can start from mid to late July and end mid-October. Significant counts, in the moderate range, occur 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 low to moderate range, with the occasional high count observed. The season can start from late June to mid-July and ends late September to mid-October.
Plantago sp.- The counts are in the low range but highly sensitized individuals may react even at these levels. The season can start mid to late June and ends early September.
Cruciferae sp.- The mustard and cabbage family are responsible for contact dermatitis and food allergies. They are not necessarily considered important in airborne allergies, since they are mostly insect pollinated, but a significant amount of pollen is observed in our samples at this location. The season can start late June and can last until late August. Mostly low and moderate counts are observed.
Diatrypaceae sp.- The counts are sporadic with some very high counts. The season is from late March to early October.No known allergic properties.
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.
Erysiphe (Oospora) sp.- 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 sp.- 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 sp.- 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 sp. & 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 : 3 March 2015
The information presented here is designed to inform, not replace, the relationship that exists between a patient and a medical professional.