Rob Amburgey | Ragweed, allergies and farmers

Published 11:45 am Wednesday, October 19, 2016

The phrase “hay fever” often is misleading. It might seem that hay fever is caused by cutting hay, however, you can usually blame those reactions on ragweed.

Ragweed is a common foe both to allergy sufferers and to crop producers. In late summer, people may suffer allergic reactions associated with plant pollens, often ragweed plants. Ragweed also has the potential to severely interfere with crop production and greatly reduce crop yield.

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Ragweeds are native species that grow throughout the United States. Individuals who are sensitive to the plant’s pollen are usually very aware of its presence. When plants begin to flower in August and early September, the airborne pollen is the culprit for the severe irritation in sensitive individuals. When exposed to the oil the plant produces, some people develop dermatitis effects.

According to J.D. Green, Extension Weed scientist, Ragweed also can impact agricultural production, especially when present in corn, soybeans and pasture fields. If it’s not adequately controlled, ragweed can cause significant crop yield loss and reduce pasture productivity. The combination of the cost of control efforts and the yield loss has an economic impact on farmers.

Three distinctly different ragweed species can be found in Kentukcy: common ragweed, giant ragweed and a lesser known species called lanceleaf ragweed. All these species are summer annuals and they only reproduce by seed.

Common ragweed is the most widespread and reoccurring of the ragweed species in the United States. It can grow up to 30 inches in height. These common plants tend to be slightly branched, but are best distinguished by their deeply divided leaves with a lace-like appearance. As it matures, green flowers blossom on slender stalks near the top of the plant. Though they are not showy, they do produce a bountiful crop of yellow pollen.

Giant ragweed matures into a much larger plant compared to common ragweed. Kentucky farmers sometimes call it “horseweed” because it can grow up to 10 feet in height. Its leaves are simple, forming three to seven deep lobes, or occasionally, forming no lobes at all. As the plant matures, it can also have green flowers on a slender stalk, capable of producing a bountiful crop of yellow pollen and new seed.

You’re more likely to find the lesser known lanceleaf ragweed in pastures, hay fields and other non-cropland sites. It can grow up to 36 inches in height and its leaves have a simple, somewhat lance-like appearance with three distinct points – the center point is larger than the two on each side.

With the end of summer, comes ragweed pollination, so allergy sufferers be aware. But as you sneeze don’t forget, those ragweeds don’t just impact your health, they are also likely wreaking havoc on your local farmers.

For more information on ragweed or other weeds, contact the Jessamine County Cooperative Extension Service.