Offensive against exotic hay fever plant alsemambrosia: ‘Get it out of your garden’

It is a feared plant for hay fever sufferers: the wormwood mbrosia. Five institutions are calling for the plants to be removed from gardens before they flower in the coming weeks.

Alsemambrosia is an exotic plant that probably ended up in the Netherlands via bird feed. The plant will flower this month and then spread large amounts of pollen that can cause serious complaints in the group of hay fever patients who are allergic to that specific type of pollen. That’s quite a lot of people, says biologist Maurice Martens of Pollennieuws/Flora van Nederland. Alsemambrosia falls under the herbal pollen allergies, and about 1 million people in our country suffer from it to a greater or lesser extent.

Today there is a ban on wormwood mbrosia seeds in bird food. But the seeds can remain viable for up to forty years, so that the plant sometimes still emerges in the garden.

Pollennieuws/Flora van Nederland is one of the organizations calling on people to look for the exotic in their garden, together with the Food and Consumer Product Safety Authority (NVWA), the Leiden University Medical Center, Wageningen University and knowledge organization FLORON.

In this video you can see how pollen is measured and what it means for people with hay fever:

“This has been coming back every year around this time for about thirteen years,” says Martens. “The plant is not very common in the Netherlands yet, but it is spread all over the country. And where it is, it causes problems.” Because the wormwood mbrosia continues to bloom into October, the hay fever season is extended by at least two months.

The government must ensure that sagebrush mbrosia is banned from public areas, but private garden owners must look for it themselves. In 2022 it turned out that 60 percent of the hundreds of reports came from private gardens, which managers of public green spaces cannot do anything about.

“That’s why we’re making that call this year. People often have trouble recognizing the plant. The leaves resemble those of other plants that are traditionally present in our country.”

If you want to remove the wormwood ragweed from your garden, it is better to wear gloves, because the species can also cause skin complaints. If the plant is already flowering, it is also advisable to wear a face mask and safety goggles, says the NVWA.

Once pulled out, plants are not allowed in the organic waste container, the organizations warn. “They should not be disposed of with garden waste, but with residual waste,” says Martens. “You really have to tackle that plant firmly. Otherwise it will continue to proliferate.”

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