Giant Ragweed also known as Buffalo Weed, Great Ragweed, Bitterweed, Bloodweed, Horse Cane, Tall Abrosia. Giant Ragweed is an annual plant in the aster family, native throughout much of North America. Its flowers are green and are pollinated by wind rather than by insects, and the pollen is one of the main causes of late summer hay fever. Flowers are borne from midsummer through early fall. The plant is erect, growing to over 6 meters, though 2 - 3 meters is more typical.
Giant Ragweed is one of the most competitive weeds found in North America At average distributions it can reduce corn crop yields by 55% and soybean yields by 52%. It is very difficult to control Giant Ragweed through mechanical means or herbicides, but it does not tolerate mowing, so planting small grains in succession is an effective way to suppress infestations.