🥒 Zucchini How hard it is to control: ★★☆☆☆ 2/5

Aphids on zucchini

The cotton aphid and the peach-potato aphid form colonies on courgette leaf undersides and shoot tips. Besides sucking sap and fouling plants with honeydew they transmit cucurbit mosaic viruses.

Symptom photos

Aphids — Shoot tip — dense aphid colony on young leaves — Shoot tip — dense aphid colony on young leaves Photo: Ronald Smith, Auburn University, Bugwood.org, licence CC BY 3.0 us

Aphids — Winged aphid on the underside of a leaf — Winged aphid on the underside of a leaf Photo: Clemson University - USDA Cooperative Extension Slide Series, United States, licence Public domain

Symptoms

Dense aphid colonies on leaf undersides and shoot tips
Young leaves curling and puckering
Sticky honeydew on leaves and fruit
Black sooty mold growing on the honeydew
Shoot tips ceasing to grow and fruitlets dropping

What it does to the crop

Young leaves and shoots deformed
Transmission of mosaic viruses that cannot be cured
Fruit fouled with honeydew and needing washing
Weakened plants and a smaller crop

What encourages it

Warm, still weather from June onwards
Too much nitrogen and lush growth
No beneficial insects around the crop
Weeds acting as a breeding ground for aphids

Prevention

Check leaf undersides and shoot tips once a week
Sow nectar plants for hoverflies and ladybirds
Keep nitrogen feeding moderate
Wash the colonies off with a strong jet of water
Clear weeds from around 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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