For allergy sufferers, spring often brings sniffling, sneezing and watery eyes, said University of Illinois Extension horticulture educator Rhonda Ferree.
“One culprit is pollen from flowers of trees, shrubs, grasses and weeds,” explained Ferree. “Though most of these bloom for just a short period, something is almost always blooming. In early spring, it’s the trees and shrubs. In summer the main pollen source is flowering grasses. In late summer and fall, weedy plants from roadsides are the problem.”
Pollen is an important part of plant reproduction and must be moved around from flower to flower. Showy flowers attract insects such as bees, which help pollinate the flowers, but not all plants use insects. Most plants that cause allergies use wind to spread their pollen.
Not all pollen causes allergies. Allergenic trees are usually a problem from March through May and include maple, willow, poplar, elm, birch, mulberry, ash, hickory, oak and walnut. Grasses are more powerful allergens than trees and bloom from May through summer. A few allergenic grasses include orchard grass, bluegrass, timothy, Johnson grass, Bermuda grass and redtop.
“Late-summer and fall allergenic plants include many weeds such as ragweed, pigweed, lambs quarters and wormwood,” Ferree said.
“Common and giant ragweeds are serious hazards to hay fever sufferers. Both types of ragweed are included on the Illinois noxious weed list for municipalities. It is illegal to allow ragweed to grow on ground you own or work on within any municipality in Illinois.”
The best way to manage these pollen producers in the landscape is through proper identification. While it is impossible to completely eliminate allergies, because pollen travels great distances, identifying and eliminating plants in the immediate area can help.
“The greatest allergy offenders are grasses and weeds, so try to keep them from blooming through mowing and weed management programs.
“For some dioecious plants, you can plant the female instead of the male plants, because it’s the males that produce pollen, but remember that female plants produce all those seeds,” Ferree said.
Pollen and mold counts are routinely provided in weather reports. Counts are usually ranked from low (1) to high (10) and indicate to allergy sufferers the potential for symptoms of hay fever or asthma.