Many fungi and bacteria
Hosts, Symptoms & Signs
- caused by many fungal and bacterial pathogens
- affects all ornamentals
- leaves start to develop brown to black spots in varying sizes
- in some cases, the brown areas will fall out leaving a hole behind
- in some cases (i.e., black spot on roses), infected leaves will turn yellow and fall off
- overwinter in fallen leaves or diseased branches
- spores land on leaves and germinate during moist conditions and colonize the leaf
- fruiting structures develop on lesions; spores spread from lesions during wet conditions, colonizing new areas of the same, or nearby leaves
- bacteria from lesions are washed across the leaf and enter new leaves through openings like stomates or small wounds
- Rake and remove leaves in the fall.
- Apply fungicides and bactericides like copper to prevent the spread to uninfected leaves; these will not cure infected leaves.
- Avoid wetting leaves with irrigation.