🥒 Zucchini How hard it is to control: ★★★☆☆ 3/5

Gray mold on zucchini

Botrytis cinerea enters the courgette fruit through the withering flower. The tip of the fruit rots first, then the mold covers it with a beige-grey, dusty bloom.

Symptom photos

Gray mold — Fruit tip — dense, beige-grey layer of spores — Fruit tip — dense, beige-grey layer of spores Photo: Schlaghecken Josef, licence CC BY-SA 4.0

Gray mold — Fruit — mould spreading from the flower remains into the tissue — Fruit — mould spreading from the flower remains into the tissue Photo: Schlaghecken Josef, licence CC BY-SA 4.0

Symptoms

The fruit rotting at the tip, from the withered flower end
A beige-grey, dusty bloom of spores on the rotting tissue
Watery, soft rot working into the fruit
Flowers and fruitlets rotting and dropping
Brown constrictions on the stems where they are damaged

What it does to the crop

Fruitlets and young fruit lost
Fruit rotting after picking, in storage
Sections of stem dying back
Losses climbing sharply in cool, wet summers

What encourages it

Humidity above 90%
Temperature 15-23°C with cool, rainy days
Withered flowers left hanging on the fruitlets
A crowded crop and fruit lying on wet soil

Prevention

Pick the withered flowers off young fruitlets
Harvest regularly, without leaving fruit on the plant
Mulch so the fruit does not lie on wet soil
Thin the leaves for better air movement
Take infected fruit out of the crop

⚠️ Before you reach for a spray

This atlas is informational and still growing — different diseases can look almost identical. Confirm the diagnosis and read the product label before applying any plant protection product. If you are unsure, ask your local extension or advisory service.

Keep the disease atlas with you in the garden

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