ALL ABOUT WITCHES BROOM

– Tim Attwell

Thank you to Henriette Botha for an interesting article about Witches Broom in a thirty-one-year-old issue of Farmers’ Weekly, 3 January 1985 to be precise.

So what is Witches Broom? Nothing to do with Halloween, you’ll be happy to know. Regular botanical ramblers in the fynbos often see what appears to be a dense, brush-like appendage on protea bushes, exactly where a flower should be. For all the world the brush-like appendage looks like a parasite, only it’s not a parasite, it’s very much part of the affected protea, the product of a disease caused by a microscopic parasite – an unclassified phytoplasma.

Witches Broom on Protea cynaroides (1)
Witches Broom on Protea cynaroides (1)

“So what are phytoplasmas?” you ask. The short answer is that they are bacteria that, in the case of protea species, cause the diseased plant to produce dense clusters of tiny leaf-like structures instead of flowers, a process known as “phyllody”. The prognosis for the affected protea bush is not good. Yellowing of leaves and the gradual deterioration of the plant is almost inevitable and it is unlikely to produce seed and another generation of proteas.

Phytoplasma bacteria are transmitted from one bush to another by tiny insects such as leafhoppers, planthoppers and plant lice which feed on the phloem tissue of plants. Having fed on the phloem tissue of a phytoplasma affected plant, they become vectors for the phytoplasma and the disease spreads.

Witches Broom on Protea cynaroides (2)
Witches Broom on Protea cynaroides (2)