Fusarium oxysporum
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Fusarium oxysporum is an incurable fungus that enters through the roots and then slowly spreads into the plant.
Species of Schlumbergera, Rhipsalidopsis and indeed most cacti and succulents are susceptible to F. oxysporum
Plants stop growing. Foliage turns a reddish-purple. Roots can be completely brown and rotten.
The vascular tissue throughout the plant is characteristiclly orange/brown.
When moisture is high the mycelium of the fungus can develop extensively and cover the entire plant .
Eventually plant parts above ground are coated with reddish-brown , salmon-coloured or violet spores.
When cut open, the plant has a pungent odour.
Made worse in hot weather.
Dispose of all infected soil and plant matter. Sterilise pots.
If disease has not progessed too far, healthy parts of the plant can be saved. Cut with a clean (sterile) sharp knife, treat the cut surfaces with charcoal or sulphur dust and treat as cuttings.
Drench with Benomyl.
Thiophanate methyl is used on some cacti and is effective in controlling Fusarium diseases. Mancozeb is labeled for christmas cactus and may also aid in disease control. Reduction of water applications greatly reduces spread of the pathogen to aerial portions of the plants, thus reducing disease severity