Botrytis / Grey Mould
Botrytis cinerea
Fuzzy grey mould on soft fruit and dying flowers. Thrives in humid still conditions. Major problem on strawberries and tomatoes.
Background
Botrytis cinerea is a broad-host-range necrotrophic fungus. It colonises dying tissue — senescent flower petals, damaged leaves, split fruit — then moves into healthy tissue. In humid weather it sporulates prolifically, producing the characteristic grey fuzzy mould on affected surfaces.
How to identify
- Soft watery rot of fruit, petals or stems
- Distinctive fuzzy grey mould coating the rotted area
- Sometimes ghost spots on tomato fruit (small white halos) where spores germinated but did not establish
- Dark lesions on stems, especially after wounds
Life cycle
Spores wind-borne or rain-splashed. Germinate on wet surfaces in 4-8 hours. New spores on rotted tissue in 3-5 days. Overwinters as sclerotia in crop debris.
Weather triggers
- Temperature: 10-25°C
- Humidity: >85%
- Rainfall trigger: >2mm
- High humidity and extended leaf wetness. Still cool humid weather is peak risk.
Peak season (southern hemisphere)
Red = active season · Dark red outlined = this month
Affected vegetables & crops
Click any crop to see current prices and growing info.
Climate zones at risk
Organic & low-impact control
- Remove affected fruit and dying flowers promptly
- Improve airflow — prune and space plants
- Avoid overhead watering late in the day
- Copper-based protectants at first sign
Chemical control
- Several systemic fungicides (boscalid, fenhexamid) registered for commercial use
- Home gardeners should focus on sanitation and airflow
Always read product labels — registrations change.
Prevention
- Stake and prune for open airflow
- Clean up dying flowers and fallen fruit
- Mulch to prevent soil splash
Companion planting
No direct companion effect.
Biosecurity
Worldwide distribution, no quarantine issue.
Sources
- Agriculture Victoria — Botrytis in horticulture
- NSW DPI — Grey mould in vegetables
Accuracy confidence: high. We update this library as new extension guidance is published.