Cause Many fungi and bacteria cause a leaf spot on Dracaena spp., but Phoma draconis (formerly Phyllosticta draconis) is most common. Peperomia also is susceptible. Wet, humid conditions favor disease development. Yellow spots can also be from magnesium deficiency.
Symptoms Lesions appear mainly on older leaves, starting as irregularly shaped, yellow areas that later turn brown with a purple margin. Fungal fruiting bodies (pycnidia) form in necrotic areas. Occasionally, a bright yellow halo may form around older lesions.
Cultural control
- Reduce moisture on leaves. Water from below foliage.
- Remove and destroy infected leaves.
- Move to a location with better light, and add Epsom salts for the yellow-spot condition.
Chemical control Several fungicides are registered but not recommended for controlling this problem in the household.
Reference Chase, A.R. 1987. Compendium of Ornamental Foliage Plant Diseases. St. Paul, MN: APS Press.