The world is returning to something resembling a state of equilibrium.
The collective sigh of relief is moderated by the knowledge that the grass and weeds are growing with wild abandon. Given the substantial and consistent rains during the spring of 2022, the growth and expansion of sneeze-inducing weeds has been tremendous.
The primary offender-to-be is common ragweed (Ambrosia artemisiifolia), an herbaceous plant in the Asteraceae family native to North America. Its capabilities to induce all the negative hay fever symptoms far exceed its reputation as a poster plant for tissue paper sales.
Curiously goldenrod, the common early autumn wildflower, is often blamed for the onset of sneezing and itchy, watering eyes. In reality, it is guilt by association for the highly visible goldenrods.
Currently ragweed is part of the early summer green background of panhandle Florida. The currently innocuous weed will become an allergy nightmare in a few months.
Unfortunately, at least for the goldenrod, they both bloom at the same time and goldenrods’ flowers are much easier to identify and blame. For the record, Goldenrod pollen is too heavy and sticky to be blown far from the flowers, and if there is an allergic reaction the unlucky person must have had very close contact with the bright yellow blooms before symptoms begin.
Common ragweed, and there are other species besides the common, is most often found in disturbed habitats such as cultivated fields, orchards, home or commercial landscapes and roadsides. In panhandle Florida, it is especially abundant along ditch banks where its seeds are easily disbursed by wind and water.
Common ragweed growing in home landscapes will compete with shrubs for light, moisture, nutrients, and space, resulting in significant performance losses from preferred shrubs. This native nuisance can rapidly grow to more than seven feet in height and dominate companion plants.
A prolific seed producer, it is capable of producing up to 62,000 seeds per plant when growing under ideal conditions. Even worse, these seeds can remain viable for many years in undisturbed soil.
While still able to blend into the weedy green landscape of early autumn, the tiny white blooms are releasing billions of pollen grains into the environment. Allergy sufferers can tell without even seeing the source of their sinus misery.
Dormant seeds of this species require a period of exposure to cold temperatures to germinate. Germination is optimal in the spring at soil temperatures of 50 to 80 degrees Fahrenheit.
Temperatures above 86 degrees will halt germination (at least a positive to all the recent 100 plus temperature readings) and send the seeds back to dormancy. After a repeat of the chilling requirement the following winter germination will begin again.
The mature plants are erect and branching with a shallow taproot which produces a fibrous root system. Stems are green to purple with long rough hairs which are usually obscured from view by the medium, green-colored leaves.
The leaves are compound, deeply lobed, and usually much wider at the base than the tip. Mature leaves are mostly hairless, but small leaves often have hairs on the underside.
Inconspicuously small, about 1/8th inch, the green male and female flowers are present on separate heads of the same plant. Male flowers are at the top of the plant and usually drooping, while the female flowers are in the center of the upper leaves and branches
Individual plants produce in excess of one billion wind-dispersed pollen grains, too many of which make it to the noses of north Florida residents.
This plant can be controlled in landscapes with mowing and over-the-counter herbicides, but with 2022’s bumper crop sporadic control may offer little relief to sinus sufferers.
As the old saying goes, misery loves company so buy an extra box of tissue. In a few months you can share it with others affected by common ragweed induced hay fever.
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