Facts about Ragweed
Total eradication of ragweed is considered impossible, owing to the plant's frugality and tremendous seed-producing capability.
Areas where ragweed has been reaped should be mowed down every three weeks to prevent regrowth.
The act of manually uprooting ragweeds, sometimes shown in the media for public awareness purposes, promises more than it can deliver.
Great ragweed ("Horseweed"; A. trifida) may grow to four meters (13 feet) or more.
Ragweeds occur in temperate regions of the Northern Hemisphere and South America.
Common ragweed (A. artemisifolia) is the most widespread of this genus in North America and attains a height of about a meter (three feet).
Ragweeds are annuals, perennials, and shrubs and subshrubs (called bursages), with erect, hispid stems growing in large clumps to a height of usually 75 to 90 centimeters (29.5-35.5 inches).
Despite this important negative impact on humans, ragweeds do have valued ecological functions.
Anecdotal claims are made of honey giving some relief for ragweed pollen allergies, which is noteworthy because honeybees very rarely visit ragweed flowers, and even then only for pollen.
The seeds are an important winter food for many bird species, and ragweed plants are used as food by the larvae of a number of Lepidoptera (butterflies and moths).
Common ragweed (A. artemisiifolia) and Western ragweed A. psilostachya are considered the most noxious to those prone to hay fever.
Ragweeds prefer dry, sunny grassy plains, sandy soils, and grow along river banks, along roadsides, disturbed soils, vacant lots, and ruderal sites.
Today, no area in the United States is ragweed pollen free, and moving can only offer a degree of relief.
One efficient method for large-scale ragweed extermination is chemical spraying.
Ragweeds bloom in the northern hemisphere from early July to mid-August or until cooler weather arrives.
That being said, ragweed is best uprooted in late spring, before the flowering season and before a strong root system has developed.
Other animals, such as some ungulates, also will forage on ragweed, and various birds and small mammals will use it as habitat or for nesting material.
Ragweed pollen can remain airborne for days and travel great distances, affecting people hundreds of miles away.
Ragweeds—mainly common (A. artemisiifolia), Western (A. psilostachya), and great ragweed (A. trifida)—were accidentally introduced to Europe during World War I; they thrived and have greatly spread since the 1950s.
Common ragweed (A. artemisiifolia) and Western ragweed A. psilostachya are considered the most noxious to those prone to hay fever.