Allergic Living’s Guide to Fall Allergies

in Outdoor Allergies
Published: July 2, 2010

Fall allergiesIn autumn, it’s an allergic onslaught. Ragweed and molds are in procreating mode, filling the air with nasty pollens and spores. Allergic Living magazine examines the season’s biggest offenders, and offers tips to keep the sneezing, watery eyes and general misery at bay.


Of the sources of autumn allergy misery,ragweed is by far the worst. It is the most common cause of seasonal allergies at this time of year and it’s everywhere. In the one year a ragweed plant lives, it will produce as many as one billion grains of pollen that can be carried by the wind up to 650 kilometres (400 miles) away. Giant and common ragweed are found across North America (though less commonly on the coasts), with the prime blooming season running from late August until the first frost kills off these adaptable plants.

Other Weeds

Though ragweed is the worst offender, others can be problematic for those with allergies:

White Cockle (Silene pratensis) – Grows up to a metre tall, with oblong leaves that are 2 to 10 cm long (1 to 4 inches) and 2 cm (1 inch) wide. White flowers open in the evenings; a prolific seed producer.

Cow Cockle (Vaccaria pyramidata) – Also known as China cockle, this weed has pretty bright pink flowers and bluish-green leaves. Height can reach 60 cm (2 feet).

Mugwort (Artemisia vulgaris) – Perennial; grows between 0.5 to 2 metres (1.5 to 6.5 feet), with a slightly hairy stem that is often reddish-brown. Leaves are dark green on top and silvery underneath; it gives off a sage-like aroma.

Curled Dock/Narrow-leaved Dock (Rumex crispus L) and Broad-leaved Dock (Rumex obtusifolius L) – Long, dark green leaves with wavy edges form a base for a metre-long stem with clusters of green flowers.

Amaranth/Pigweed (Amaranthus) – a family of annual weeds that share similar characteristics: alternating oval-shaped leaves, green flower clusters and smooth stems. Prostrate Pigweed grows along the ground while Redroot Pigweed and Green Amaranth grow upright.

Lamb’s Quarters (Chenopodium album L) – An annual with bluish-green leaves that grows up to 2.5 metres (8 feet) high on stems with purple or red blotches. Flowers are small (up to 3 mm) green petal-lesspods with a blue tinge.

Russian Thistle (Salsola kali L) – Thin, spiky leaves sprout from multiple branches that are often striped with red. Purple-tinged stems grow to more than 1 metre (about 4 feet) tall, which dry out and break off when mature, forming “tumbleweeds” that spread seeds.

Plantain (Plantago major L) – Long, narrow flower clusters (7 to 30 cm/2.5 to 11.5 inches in length) hold numerous greenish-white flowers with wind-distributed pollen. Plant grows to 60 cm (2 feet) high, with smooth, spade-shaped leaves.


Mold can be found anywhere it’s damp, including in piles of decaying plant matter, composters, gutters, rotting wood (like those porch steps you meant to fix) and inside the house in basements, bathrooms and laundry rooms. Several types of mold cause allergy symptoms, and many of them thrive both indoors and out, including Alternaria, Aspergillus, Cladosporium, Panicillium, Epicoccum, Fusarium and Bipolaris. Your allergist can test you for sensitivity to the different types, though all are hard to avoid completely.

According to the American Academy of Allergy, Asthma & Immunology (AAAAI), the weather plays a large role in how badly a mold allergy will flare. The damper the conditions, the more mold there will be.

How Mold Behaves

Mold allergen is spread on the wind in the form of spores, much like the lighter plant pollens. However, unlike weeds, which are generally destroyed by the first good cold snap, many molds simply become dormant over the winter, reappearing in the spring in soggy organic matter such as piles of mulch. During drier summer months, the mold allergic person’s symptoms wane, only to resurface in the fall with more rain and dropped leaves on the ground.

Inside, basements are a fungus’s best friend. With damp walls, leaky foundations, storage boxes full of paper, improper insulation and carpeting, the subterranean level can be the perfect breeding ground. That “musty” basement smell is a dead giveaway that mold has moved in.

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