Ambrosia: Information for allergy sufferers

What is ragweed?

Ambrosia, also known as mugwort ragweed or mugwort ragweed, is a plant from the daisy family that is considered highly allergenic, especially for patients with hay fever . It was originally native to North America, but was introduced to Europe through trade in goods. Ambrosia is already a big problem due to its rapid spread and profile as a weed, especially in southern and south-eastern Europe. In Germany there have been mostly small and rather unstable populations of the most common species Ambrosia artemisiifolia.

Danger for allergy sufferers

Each annual plant produces around 60,000 seeds that are viable for up to 40 years. The plant can be pollinated by the wind, which carries the aggressive pollen hundreds of kilometers away. They also use vehicles, trains and soles of shoes as a means of transport.
The pollen are very small and can get deep into the bronchi. About 80 percent of all people who have pollen allergies also react to ragweed. Almost half are subsequently allergic to it. And it can even affect people who previously thought they had nothing to do with allergies. In addition, the plant often causes particularly severe allergic reactions such as asthma – which has earned it the name “asthma plant” in Australia. But even touching the hairy stems can trigger a contact allergy. So extreme caution is required!

Ragweed pollen has been systematically recorded at around 40 measuring stations throughout Germany since 2006.

The most important features

Ambrosia germinates from April to August. From then until October, their blue-violet inflorescence usually appears. As a small plant, it can easily be confused with, for example, a marigold (tagetes) or mugwort. In these two plants, the most important distinguishing feature is the green, slightly hairy underside of the ragweed, in contrast to the white underside of the mugwort. While other plants continue to grow, ragweed takes a one-month growth pause when it reaches a size of ten to 15 centimetres. You should definitely notice this in your own garden: everything is sprouting and growing and there is something in between that is doing nothing at all – it is worth checking more closely in such cases. Because the spread of ragweed must be prevented in any case.

Due to the rapid spread, your help is also needed: Report all finds of Ambrosia in the garden, or wherever you discover them! You can find a registration form at: http://www.forum-biodiv.de/kontakt.html

Plant removal tips

• Always wear gloves and avoid any physical contact.
• In the flowering period from August to December, a face mask should also be worn!
• Remove the plants with roots. Pruning or mowing is of no use as it will start flowering from July no matter how big it is.
• Dispose of the plant in the household waste in a closed bag. Under no circumstances dispose of it in the compost or in the organic waste bin.
• Pay particular attention to places where birdseed (also known as tit rings) has been placed.