Ambrosia pollen is a major cause of allergies and flies until October. The plant is therefore hated by hay fever sufferers. The bitter: It really picks up speed on roads, of all places.
After birch, hazel and grass, many allergy sufferers in this country have long since been prepared to be tormented year after year by the pollen of new, immigrant species. The already hated ambrosia has an extremely unpleasant additional effect: of all places, it becomes really aggressive on roadsides.
Nitrogen dioxide (NO2) from exhaust gases causes stress in the plant. This changes the protein composition of the pollen . This is what researchers at the Helmholtz Center in Munich found out. The amount of so-called allergenic proteins is increasing, explains the head of the Institute for Biochemical Plant Pathology, Jörg Durner. Depending on the allergen, by a factor of two to ten.
For those affected, this ultimately means: The body releases more histamine, and this causes allergic reactions – hay fever and asthma. Skin inflammation is also possible. And: “An ambrosia plant can shed between 3,000 and 60,000 seeds in its one-year life cycle,” explains Bavaria’s Minister of Health Melanie Huml (CSU). “It can also release up to a billion pollen into the air.”
Mugwort ragweed: Climate change is causing stocks to grow
NO2 itself has a damaging effect on the mucous membrane. “Now more aggressive pollen meet more irritated mucous membranes,” says Durner. How strong the effects are together, whether they add up or exponentiate – i.e. increase significantly more blatantly – is now to be tested on a model. Here the scientists are still at the beginning: “The easiest way would be to have a person with ambrosia in a chamber that is treated with NO2. But of course that is not possible,” says Durner. Now the question is whether an animal model should be used or whether an artificial mucous membrane will be developed for test purposes.
The North American mugwort ragweed, Ambrosia artemisiifolia , also called upright or mugwort-leaved ragweed, was probably introduced to Europe years ago via bird seed. In Germany, according to Matthias Werchan from the German Pollen Information Service Foundation, it is mainly represented in the warmer south. The Ministry of Health in Bavaria alone recently counted 393 larger stocks in the Free State. But in Brandenburg, for example, there are also stocks “beyond good and evil,” said Werchan. Ambrosia is also spreading because of climate change.
Your pollen is one of the strongest allergy triggers – more so than grass and birch, for example. The weeds, which can be up to 1.80 meters high, do not bloom until around mid-July, and pollen counts from August to October. For allergy sufferers, this may mean an extension of the suffering period by around two months.
Tear out ambrosia – preferably with a face mask
The bitter: According to Werchan, there is another problem, especially at roadsides, where the pollen is becoming more aggressive. “The green strips on the motorways are mowed regularly. Then the plants are pulled along and the seeds are distributed in the ground.” They could germinate there years later. The Ministry of Health in Munich therefore recommends tearing the plant up – only with gloves and, in the case of flowering plants, even with a face mask – and dispose of it in a plastic bag with household waste. Authorities should be consulted for stocks of around 100 plants or more.
Since 2007, the Julius Kühn Institute has been taking action against ambrosia nationwide and also the Free State with action programs. “All in all, an uncontrollable spread like in other countries has been prevented so far,” says Minister Huml . Werchan and Durner are of the opinion that far too little is being done in Germany – also politically. According to the information, there are just about 40 measuring stations in the entire republic to record pollen count.
Werchan also refers to Switzerland, which has enshrined in law that ambrosia must be combated. “The plant is almost wiped out again,” he says. In Germany there are only local actions. “The fight is much cheaper than waiting.” Bavaria’s head of department Huml says: “We are observing in Bavaria whether a legal obligation to report and control ragweed plants could also become necessary here.”
However, Professor Durner from the Helmholtz Center for Ambrosia has something good to say about it: “This is a great model for research because a single plant develops so much pollen.”