Leaf Mold
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Treat, then re-check in 5–7 days
Pick off the worst material, apply the organic option below, and look again after five to seven days. If the spread continued, escalate rather than repeating the same treatment.
Rain and irrigation splash
Water splashing off soil and infected leaves carries it upward and along the row. Watering at the base and mulching the soil surface break the route.
It carries over to next season in soil, debris or seed — which is why rotation matters here, not just treatment.
Hot compost only
A heap that reaches and holds 55–65°C throughout will destroy it. A cool corner heap will not, and will return the problem to the beds with the finished compost.
When and where to look
Scout the planting while temperatures hold between 18°C and 27°C, with humidity above 85%, after rain or heavy dew, while the leaves are still wet. Risk builds after roughly 10 unbroken hours of those conditions, so the morning after such a night is the moment to look.
Rule these out first
Same category, and at least one host crop in common — so they are genuinely confusable in the same part of the garden.
The signs that lead here
Full problem lists for these crops
About
Leaf mold (Passalora fulva) is a major greenhouse and high-tunnel tomato disease driven by high humidity and poor ventilation, rarely serious outdoors but devastating under cover.
Symptoms
Pale green to yellow blotches on the upper leaf surface with olive-green to brown velvety mould on the underside; leaves curl, brown and drop, starting low in the canopy.
Organic Treatment
Drop humidity below 85%, increase ventilation and spacing, remove infected leaves, and spray copper or Bacillus subtilis.
Chemical Treatment
Chlorothalonil or mancozeb, alternated with difenoconazole in protected culture.
Prevention
Ventilate and heat greenhouses to avoid condensation, space plants, prune lower leaves, and grow resistant varieties.
Crops at risk
Related problems
Leaf Mold risk by location
Each location has a month-by-month profile computed from the weather archive: how many hours a year actually meet this disease’s thresholds.