Troubleshooting
Courgette problems — and how to fix them
Courgette (Cucurbita pepo 'Defender') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Powdery mildew
White powdery coating on leaves is almost inevitable late in the season, weakening plants. Space for airflow, water at the base, remove the worst leaves, and choose mildew-resistant cultivars.
Poor fruit set and rotting tips
Young fruit shrivels and rots at the tip when cold, wet weather or lack of pollinators prevents pollination. Encourage pollinators, hand-pollinate if needed, and pick fruit young to keep plants productive.
Cucumber mosaic virus
Yellow-mottled, distorted leaves and stunted, deformed fruit signal this aphid-spread virus. There is no cure; control aphids, remove and destroy infected plants, and grow resistant varieties.
Slugs on seedlings
Slugs and snails can destroy young transplants overnight. Protect seedlings with barriers and traps, plant out only well-grown plants, and keep the surrounding area clear of debris.
Prevent courgette problems before they start
Most courgette issues are care-mismatch, not bad luck. Dial in the basics:
Looking for courgette in general rather than its problems? Read the full courgette care guide — light, water, soil and feeding.
Courgette problems — FAQ
Why is my courgette powdery mildew?
White powdery coating on leaves is almost inevitable late in the season, weakening plants. Space for airflow, water at the base, remove the worst leaves, and choose mildew-resistant cultivars.
Why is my courgette poor fruit set and rotting tips?
Young fruit shrivels and rots at the tip when cold, wet weather or lack of pollinators prevents pollination. Encourage pollinators, hand-pollinate if needed, and pick fruit young to keep plants productive.
Why is my courgette cucumber mosaic virus?
Yellow-mottled, distorted leaves and stunted, deformed fruit signal this aphid-spread virus. There is no cure; control aphids, remove and destroy infected plants, and grow resistant varieties.
Why is my courgette slugs on seedlings?
Slugs and snails can destroy young transplants overnight. Protect seedlings with barriers and traps, plant out only well-grown plants, and keep the surrounding area clear of debris.