Himalayan balsam is a prohibited noxious weed in Alberta, other portions of North America, Europe, Asia, and New Zealand. Unfortunately, it is growing in Slave Lake and the M.D. of Lesser Slave River. Under the Weed Control Act, land owners must eradicate prohibited noxious species.
Alberta Invasive Species Council says, “Seeds germinate in the spring to produce dense, even-aged stands which shade-out competing vegetation, with some plants growing to three metres tall. Himalayan balsam has a shallow, fibrous root system. In winter, erosion can occur as a result of balsam’s shallow rooting having replaced the deeper rooted native vegetation.”
Himalayan balsam likes wet soil and riparian (along streams) areas. It blooms from July to frost. The blooms attract bees and other pollinators away from native species.
When touched, the seed pods shoot the seeds far afield. Plants produce around 700 to 800 seeds, which can survive in water for two years.
Repeated mowing and hand pulling are the recommended way to remove the weed, with the plants bagged and put in landfill or burned. It doesn’t make sheep or cattle sick, but grazing is never a recommended form of noxious weed control.
Rototilling isn’t an option in riparian areas. There is no chemical specific to Himalayan balsam, also “the use of herbicides in aquatic environments requires Alberta-specific applicator certification and permits.”
“Stems are smooth, hairless, and usually hollow, tinged red-purple and are easily broken. Stems grow one to three metres tall and there may be some branching.
“Leaves are lance shaped or elliptic with pointed tips and rounded bases, and six – 15 cm long. The leaves are stalked and have sharply serrated edges. They occur opposite or in whorls. Leaf size decreases with height on the stem.
“Flowers are large – 2.5 to four cm long – in shades of pink through purple, occasionally white. Flowers occur five – 10 together in racemes (clusters on short equal length stalks) on long stems borne in the upper leaf axils. Flowers have five petals and are bilaterally symmetrical. The upper petal forms a hood over the reproductive structures (resembling a British policeman’s helmet) and the lower petals form a platform for landing insects.
“Seed capsules are 1.5 – 3.5 cm long and up to 1.5 cm wide and contain up to 16 seeds.”
Information from Alberta Invasive Species Council.