Troubleshooting Furry Mould On Fuchsia Stem

This furry mould on a ripe (woody) fuchsia stem is caused by Botrytis, a pathogenic fungus. Botrytis is a problem with fuchsias in warm muggy weather and in cold damp, still air. I spotted this yesterday and sprayed with 'Systhane' (myclobutanil). Doesn't look like it's having much effect.

If left alone, the branches die back one by one, until the fungus has destroyed the whole plant. If caught early enough, it can sometimes be cut out. However, it is often too near to the base of the plant (usually on the main stem) for this type of control.

It often starts from old decaying plant material left lying on the surface of the compost, then travels across the compost to the main stem of the plant. It is also often found at the point where a branch has been cut back and bleeding has occurred, leaving sugary sap on the stem around the wound. This is ideal food for the fungus.

Cuttings in too wet compost can also suffer due to the organic matter in the compost, which feeds the fungus. Best to use sterile perlite and water at this time of year.

PREVENTION
It seems this disease can only be contained by preventative measures applied BEFORE the fungus penetrates the plant tissue. i.e. only CONTACT fungicides and husbandry techniques are effective.

• Myclobutanil (a systemic fungicide) does seem to work on botrytis, but as a PREVENTATIVE only. Spraying it on the foliage and compost surface BEFORE ATTACK will offer resistance, just as a contact fungicide will do. So will a drop of two of bleach (chlorine) per litre of water used in the same way. This prevents the spores from germinating. I tried watering the pots with chlorinated water last year but, at the concentration used, it was only successful on older, established plants.
• Keeping the foliage and compost surface DRY is most effective. Should watering be necessary (and it often won't be), it can be done from the bottom by standing the pots in a saucer of water for about 20 minutes.
  
• Do not cut back stems too soon after watering. Best if this can be done when plant is near wilting point, just before watering (allow wound to heal first!).
  
• All dead leaves and other debris should be removed as soon as possible, before they become infected.
  
• Ventillation is useful when plants are inside, especially in winter. But botrytis also affects plants outside in the summer months.