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University of Illinois Extension

Ragweed Currently Causing Allergy Problems

September 19, 2013

It seems that many are suffering from sneezing and sniffling right now due to allergies. Although some are quick to blame the lovely, yellow blooming goldenrod, the culprit is really ragweed, states University of Illinois horticulture educator, Candice Miller.

Ragweed is currently flowering here in northern Illinois releasing its lightweight pollen grains into the air by the millions. Each ragweed plant can produce an estimated one billion pollen grains.

In Illinois you'll find two types of ragweed, both native annual plants; common ragweed (Ambrosia artemisiifolia) and giant ragweed (Ambrosia trifida).

Common ragweed is indeed common along roadsides, cultivated fields, vacant lots and pastures. It grows one to four feet tall with densely hairy stems and deeply lobed (almost ferny) leaves. Common ragweed grows well in gravelly areas along roads where it thrives under abuses that would knock out most plants.

Giant ragweed is a larger version at 13 to 15 feet tall. Its coarse, rough stems hold large, slightly hairy leaves that grow almost a foot long with three or sometimes five pointed lobes. Giant ragweed can be common in cultivated fields, fence rows, roadsides and unmown construction sites.

Since ragweed is an annual weed, the key to controlling it is getting to the plants before they set seed. Get plants removed as early as possible this fall and be sure to remove any next season as well before they flower.

Gardening during allergy season can be a challenge. Weather conditions can make a difference in the pollen levels. The most favorable conditions for high pollen are warm and dry while high humidity and rainfall lessens pollen release. Also the time of day can influence pollen levels. Pollen release is highest in mid-morning after dew has dried.

If you're an allergy sufferer and go outside during the worst times for pollen levels, horticulture educator, Sandy Mason, recommends reducing your exposure by wearing gloves, a long sleeved shirt, hat and sunglasses or goggles. A pollen mask may be necessary. After working outside take a shower and thoroughly wash hair and clothes. Look forward to October. Ragweed allergy season generally lasts through September.

Need help identifying ragweed? Call the University of Illinois Extension Master Gardener Helpline and speak with the volunteers who are available to answer your questions and identify your plant samples. There is no cost for this service. Contact: 618-344-4230 or 618-939-3434.

Source: Candice Hart, Extension Educator, Horticulture, mille116@illinois.edu

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