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Grey mould (botrytis)

Botrytis attacks soft and damaged tissue in cool, humid conditions: strawberries, raspberries, grapes, tomatoes under glass, lettuce. The grey fur is a mass of spores that puffs out when touched and spreads to the next fruit.

Fungal diseases
A strawberry rotting under fuzzy grey mould
A strawberry rotting under fuzzy grey mould

What it looks like

The grey fur is the giveaway.

  • A fluffy grey-brown mould that releases dust when touched.
    Grey fur A fluffy grey-brown mould that releases dust when touched.
  • Fruit turns brown and soft beneath.
    Soft rot Fruit turns brown and soft beneath.
  • On tomatoes, pale rings on green fruit where spores landed.
    Ghost spots On tomatoes, pale rings on green fruit where spores landed.
  • Pale lesions on stems under glass.
    Stem cankers Pale lesions on stems under glass.

How to confirm it

Touch lightly.

  1. Dust puffs

    Grey spores puff out.

  2. Damp, cool weather

    Common in wet summers and in autumn.

  3. Starts at damage

    Often begins on a dead flower or wound.

What to do

Remove, ventilate, dry.

  1. Remove affected parts

    Pick off mouldy fruit, flowers and leaves into a bag.

  2. Ventilate

    Open greenhouse vents and space plants.

  3. Water at the base

    Keep leaves and fruit dry.

  4. Tidy daily

    Remove dead flowers and leaves.

Prevent it next time

  • Keep strawberries off the soil with straw.
  • Prune for airflow.
  • Avoid damage to plants.
  • Pick fruit promptly.

What not to do

Do not leave mouldy fruit on the plant or the ground.

In the growing guides

Where the guides mention it, with plant-specific advice.

Sources

  1. Grey mould, Royal Horticultural Society