🍄Fungal diseasesSevere
Septoria Leaf Spot
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When it strikes
Temperature
20–26°C
Humidity
≥90%
Leaf wetness
Required
Season
Summer
About
Septoria leaf spot (Septoria lycopersici) is a major tomato disease in humid summers, causing heavy defoliation from the bottom up that exposes fruit and slashes yield.
Symptoms
Many small circular spots with dark borders and pale grey centres, often dotted with tiny black fruiting bodies, starting on the lowest leaves after fruit set.
Organic Treatment
Strip infected lower leaves, mulch heavily, and spray copper or chlorothalonil at first symptoms. Improve airflow with staking and pruning.
Chemical Treatment
Chlorothalonil or mancozeb every 7–10 days, alternating with azoxystrobin in severe seasons.
Prevention
Rotate away from tomatoes for 2 years, mulch, stake, water at the base, and remove debris at season end.