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All problems
Moderate
Disease

White powdery patches on leaves (powdery mildew)

Dusty white or grey patches on the upper surface of leaves, spreading until whole leaves are coated.

Commonly affects: Cucumbers, Basil, Strawberries, Tomatoes

What you'll see

  • White powdery dust on leaf surfaces
  • Yellowing and curling of affected leaves
  • Spreads quickly through the canopy
  • Reduced yield and stunted growth

Likely causes

  • High humidity (>70%) combined with poor airflow
  • Cool nights and warm days (condensation on leaves)
  • Overcrowded canopy
  • Susceptible crops grown in greenhouses without ventilation

How to fix it (step by step)

  1. 1Remove and bin (don't compost) the worst-affected leaves
  2. 2Seek advice on a registered crop treatment and follow its label, including harvest intervals
  3. 3For persistent cases, obtain qualified diagnosis before selecting a registered crop treatment
  4. 4Increase airflow with fans, prune to open the canopy
  5. 5Drop humidity to 50–60%

Stop it happening again

  • Always run a fan over the canopy
  • Space plants for good airflow — don't overcrowd
  • Avoid wetting leaves in the late afternoon
  • Choose mildew-resistant varieties of cucumber, basil, etc.

Need a second opinion?

Share dated photos, root observations, water readings and your mixing record so our team can assess the problem. Visual symptoms alone do not confirm a diagnosis.

Confirm the cause before treating the crop

Collect observations that distinguish possible causes

Record the first appearance of symptoms, the affected plants and whether old or new tissue is involved. Inspect roots, delivery and visible pests. Compare a healthy plant nearby. Record pH, EC, temperature and recent changes. Several causes may act together; the symptom title is a starting point, not a confirmed diagnosis.

Verify calibration and the complete mixing record. Product links explain nutrient roles; they are not instructions to use one bottle alone. Record your correction and assess subsequent growth because damaged leaves and fruit may not recover.

Escalate safely

Rapid wilting, collapse or spreading root symptoms need prompt checks of flow, oxygen and hygiene. Protect unaffected plants where practical and seek qualified diagnosis. Treatments must be registered for their intended crop and use and applied according to label, including harvest intervals.

When asking for help, provide dated root and leaf photos, water readings and mixing records. Do not combine nutrient changes with disinfectants or pesticides without compatibility advice. An online guide cannot confirm a pathogen or prescribe a universal chemical treatment.

Further reading

These sources support general cultivation guidance, not verified Nana Organics product performance. Current NaO instructions take precedence over another brand’s feeding schedule.