Downy mildew on pumpkin
Pseudoperonospora cubensis infects pumpkin leaves in the second half of summer. Angular yellow patches boxed in by the veins quickly brown, and the plant loses its leaves before the fruit is ripe.
Symptom photos
Symptoms
- Angular yellow patches boxed in by the leaf veins
- A grey-violet growth on the underside of the patches in humid conditions
- Patches browning and drying, then whole leaves following
- Dried leaves curling upwards
- Symptoms working up from the oldest leaves
What it does to the crop
- Leaves lost before the fruit has ripened
- Small, poorly colored fruit that keeps badly
- Sunscald on the exposed fruit
- The growing season ending early
What encourages it
- High humidity and long periods of leaf wetness
- Temperature 15-23°C with frequent rain
- Spores blown in on the wind from a long way off
- A crowded crop with poor air movement
Prevention
- Space plants widely on an airy site
- Drip-irrigate in the morning without wetting the leaves
- Remove the first affected leaves
- Grow tolerant varieties
- Clear crop debris after harvest
⚠️ 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.
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