Know your trees: Rhus tree causes allergic reactions
Find out more about the Rhus tree which has been around for decades and causes an allergic reaction in people.
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KNOW your trees and shrubs as beautiful, ornamental trees may in fact be quite toxic and cause allergic reactions.
After a stint of gardening, a Hillcrest resident broke out into a severe rash on his hands and forearms.
Bruce Burger said he was initially puzzled when, after chopping down a tree in a neighbour’s garden, he broke out into a rash on his wrists and arms.
He consulted with Dr Neil Crouch, who advised him that it was an allergic reaction to the Rhus tree or Japanese wax tree that Bruce was cutting down: Toxicodendron succedaneum.
What the expert said
Dr Neil Crouch from the KZN Herbarium, said the Rhus tree has been around for decades and causes an allergic reaction in people manifesting as a rash with welts “that drives you scatty”. He said he has also suffered a rash from this tree.
“You need more than an antihistamine such as Allergex, you need cortisone cream. The plant, its sap, pollen or sawdust causes the severe dermatitis.
“Often kids are mysteriously affected with a rash after swimming as a result of the pollen landing up in swimming pools.” He said the rash can occur a day or two after contact.
What the tree fella said
Neil McGennis, a tree fella based in Kloof, said he has found the Rhus tree all over the upper highway area. When a tree needs to be chopped down, his staff wear masks and gloves. He said many people are not aware that this tree is toxic. “When kids climb this tree they get rashes.”
What the doctor said
Kloof’s Dr Michael Westbrook said the allergic effect of the Rhus tree is quite common, usually children are brought in to see him.
“The rash has the appearance of plant dermatitis as there is an acute skin reaction when coming into contact with the tree. It presents as a stripy, raised rash (not a wheel) and I have treated hundreds of people over the years.”
Treatment for adults is a cortisone and antihistamine injection and if itching is excessive, then cortisone tablets and a cream are prescribed. A child is given a cortisone syrup, antihistamine and cream.
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But that may not be the end of it.
Dr Westbrook said what often happens is that immediately after treatment, it appears as if the rash is healing, however, it can recur on another part of the body. Eruptions can occur days later without having further contact with the Rhus tree.
The Rhus succedanea tree or Japanese wax tree
This deciduous, ornamental garden tree grows up to 5-8m high with grey-brown trunks and branches. It is a highly toxic, allergy-causing tree, causing severe dermatitis, presenting in a rash, redness, itching and blisters, wherever the skin has come into contact with the plant or its sap.
Where does this species come from?
East Asia (Japan to India) .
What is its invasive status in South Africa?
NEMBA Category 1b. NEMBA classifications: the National Environmental Management: Biodiversity Act, 2004 (ACT NO. 10 OF 2004) Alien and Invasive Species Lists, 2016 ( Category 1b: invasive species that may not be owned, imported into South Africa, grown, moved, sold, given as a gift or dumped in a waterway.
Category 1b species are major invaders that may need government assistance to remove. All Category 1b species must be contained, and in many cases they already fall under a government sponsored management programme.)
Where in South Africa is it a problem?
KwaZulu-Natal.
How does it spread?
Birds eat the fruit and spread the seed in their droppings.
Why is it a problem?
All parts of the plant are poisonous and in highly sensitive people, merely standing under a tree may be sufficient to cause a reaction. It also invades moist forest and plantation margins.
What does it look like?
Leaves: Bright green, blue-green beneath, turning soft red in autumn. Flowers: Divided into four to seven pairs of yellow-green flowers, 1-2mm long. Fruit/seeds: White or pale yellow-brown, shiny, slightly flattened, one-seeded drupes, 8-10mm across.
(From Invasive species South Africa)
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