Pests & diseases › Powdery Mildew
Powdery Mildew
White dusty fungal coating on leaves and stems. Worst on courgettes, squash, cucumbers and peas in dry summers.
Symptoms
- White powdery patches on upper leaf surfaces
- Coating spreading to cover whole leaf, then stems
- Leaves yellowing and crisping at the edges
- Reduced yields, smaller fruit
Lifecycle
Thrives in warm dry days and humid nights. Worst late summer.
What to do
- Remove worst leaves — bin, don't compost
- Spray with diluted milk (1 part milk to 9 parts water) — proven to suppress spores
- Bicarbonate of soda spray (1 tsp per litre water + drop of soap)
- Improve airflow — thin lower leaves
If it's bad
- Sulphur-based fungicides (Bayer Garden range) — organic-approved
Stop it coming back
- Water at base of plant, never on leaves
- Mulch deeply to keep roots cool and moist
- Wide spacing for airflow
- Resistant courgette varieties: Defender, Parador, Tuscany
Crops it goes for
Plan the plot, track every sowing, cook the harvest
Sowing reminders and harvest forecasts for your own frost dates, the Seed Tin, Scan Centre for any label or packet, and the Potty Mouth Garden Club. Free to start.