By Trevor Lennox, PAg, Range Management Extension Specialist, Swift Current
Absinthe Wormwood is a noxious weed in Saskatchewan that continues to spread across the prairies. It usually starts by invading disturbed areas such as cropland edges and roadsides, and then moves to hayfields and eventually into disturbed areas within native plant ecosystems.
Absinthe is unpalatable to cattle and produces allelopathic chemicals, which inhibit the growth of other plants nearby. Absinthe is a perennial with a strong pungent sage odour. It has a shrub-like appearance, with plants ranging from 0.7 - 1.2 meters (two - four ft.).
Small fine hairs cover the entire plant to produce its silvery-grey colour. The lower leaves are alternate, long-stalked and deeply lobed; the upper ones are neither stalked nor lobed and are lance-shaped. The entire plant is very aromatic, with an unmistakable sage-like scent. Because its pollen is wind borne, absinthe, like the other Artemisia species, can cause hay fever. Its odour can cause great discomfort to sensitized persons, especially those working close to absinthe infested areas. A single plant may produce as many as 50,000 seeds in a growing season and these seeds may be viable for up to four years.
Where can it be found?
Absinthe is found in dry soils, overgrazed pastures and rangelands, waste places, ditches, ravines, borrow pits, gravel piles and fence lines. It is most noticeable on fence lines and roadsides. Absinthe is found throughout Canada, but it is most abundant on the Prairies.
Absinthe does not tolerate frequent disturbance, and is therefore rarely a problem in annual crops. Mowing prior to the plant setting seed helps control its spread. Seed production is only reduced as the plant then sends out horizontal stems that will also set seed. Hand weeding, though labour intensive, works effectively to control smaller areas. It is especially important to dig out all the roots if possible. By not overgrazing, forages and pastures remain healthy and less subject to invasion. There are a limited number of registered chemicals for control of absinthe, and it may take more than one application to effectively control this weed.