When I first started working in horticulture, I didn’t realise I was allergic to so many plants. Some make me wheeze, some make me sneeze and some give me terrible rashes – but none more so than asthma weed. It’s also known as pellitory, or pellitory in the wall, sticky weed, dead nettle, Kirribilli curse, and botanically as Parietaria judaica. But no matter what it’s called – it’s a shocker.
It’s also called sticky weed because it’s covered in tiny sticky hairs which, if they touch your skin, can cause a rash, which itches and then t turns red like a burn. The plant has tiny flowers that release airborne pollen. If it gets in your eyes it can cause conjunctivitis, or up your nose can cause rhinitis and it can make you wheeze or trigger asthma attacks. One of the dangerous things about asthma weed is that it flowers all year so you’re always at risk.
You may have walked past this plant and never be affected, but like beestings and rhus trees, it builds up in your system as an accumulative poison. The more you’re around it the more likely you are to get an allergic reaction one day.
It’s a tenacious plant, growing between cracks in the wall. It also takes salt spray and wind. Not only does it grow anywhere but it also spreads easily. The flowers are sticky so the perianth sticks to clothes and animal fur to spread. They are also spread by wind and water. One square metre of the plant can produce about 250,000 seeds.
The obvious thing to do is get rid of it. Use an herbicide, like glyphosate, or hand-remove it – but wear gloves and be thorough. Ensure you dig out all the roots – because it can grow from root cuttings. Don’t throw it in the compost, but bag it instead, because it will re shoot. If you’re unsure about anything, contact your local council.
Meredith discovers the perils of asthma weed