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Black Root Rot

Thielaviopsis basicola

Black Root Rot

Black Root Rot is a soil-borne fungus that attacks the roots of a wide range of herbaceous plants causing the roots to form blackened areas and stunt the top growth.
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Stunted growth of roots and foliage. Roots turn black. Leaf yellowing or yellow leaf margins. Ultimately, branch dieback.

Growth factors

- Alkaline soils with poor drainage.


Stunted root growth
Stunted top growth
Interveinal chlorosis
Black roots
Yellow leaf margins
Branch dieback

Biological treatment

There are no biological treatments for this disease.

Chemical treatment

Using a chemical fungicide can be effective as a preventative measure but once the plants are infected they should be removed and destroyed.


Maintaining a low soil pH can help prevent infection. Growing in soil-less media. Keeping good plant and tool hygiene. Good pest control.

Affected plants

Blushing Barberton Daisy

Gerbera viridifolia

Flaming Katy

Kalanchoe blossfeldiana

Pansy 'Johny Jumpup'

Viola tricolour (Tricolor Group) 'Johny Jumpup'

Petunia flower


Petunia spp.


Euphorbia pulcherrima

Primula 'Belarina'

Primula 'Belarina'

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