🦠 Botrytis bunch rot (grey rot)
Bunch rot in damp weather: the berries get a grey dusty coating and spoil.
Grey rot is a grape disease caused by the fungus Botrytis cinerea. In damp, warm weather the fungus settles on the bunches. The berries become covered with a grey dust, split and spoil. Wine made from such grapes loses flavour and colour.
The fungus is helped by dense foliage that does not air well and stays wet for a long time. That is why growers remove leaves around the bunches: air and sun then dry the berries faster. Damage to the berries, for example from the European grapevine moth, also opens the way for rot.
Interestingly, the same fungus can be useful in dry weather. It then causes noble rot, which is the basis of sweet wines such as Monbazillac or Tokaji. The difference is the weather: dampness brings grey rot, while a dry autumn brings noble rot. If rot has already appeared, affected bunches are removed by hand at harvest. They must not reach the winery, or the wine will get an unpleasant taste.
How it connects to Wine
🦠 Botrytis bunch rot (grey rot) ← affects ← 🦠 Botrytis cinerea → kind of → 🌿 Viticulture → kind of → 🍷 Wine
Links
- Previous step
- 🦠 European grapevine moth
- What affects it
- 🌿 Leaf removal, 🦠 Botrytis cinerea
- What it affects
- 🍷 Noble rot
- Part of
- 🦠 Grapevine diseases
- Similar and different
- 🍷 Noble rot
Frequently asked questions
What is grey rot on grapes?
A bunch disease caused by the fungus Botrytis cinerea. Berries get a grey dust and spoil.
How is grey rot different from noble rot?
It is the same fungus. In wet weather it ruins the crop; in a dry, warm autumn it causes noble rot used for sweet wines.
How do growers fight grey rot?
They remove leaves around bunches for airflow, control pests such as the grapevine moth and harvest on time.
Similar
🦠 Anthracnose (grape) · 🦠 Black rot (grape) · 🦠 Esca · 🦠 Pierce's disease · 🦠 Flavescence dorée · 🦠 Grapevine leafroll