Field Identification
A symptom, not a single villain—round to angular lesions with yellow halos, dark fruiting dots, or shot holes depending on which fungus or bacterium won the lottery on your leaves. Wet leaves plus spores equals a new pattern by morning.
Spots start small, may merge, and often appear first on lower, older foliage after splashing rain or overhead love from the hose. Purely cosmetic until defoliation weakens the plant or opens sunscald.
How to Deal With It
Organic Control Methods
Copper, sulfur, or potassium bicarbonate on a protectant schedule during wet spells; neem or Bacillus-based products as part of rotation—identify host to pick rate and interval.
Antagonistic microbes (Bacillus subtilis, Trichoderma products) colonize leaf surfaces; healthy phyllosphere communities outcompete sloppy pathogens when humidity is managed.
Water at soil line, mulch to stop splash, widen spacing, prune for airflow, and choose resistant cultivars when breeders bothered to.
Strip and hot-compost or remove the bottom infected layer; sanitize tools between plants if bacterial spot is suspected.
Avoid evening irrigation; scout after storms; destroy crop debris that overwinters Pseudocercosporella and friends.
Let Nature Handle It
Natural Enemies
- Antagonistic Bacteria
- Hyperparasitic Fungi
Threat Map