Aster- Alternaria & Colletotrichum Leaf Spots: Alternaria spp. (top) and Colletotrichum spp. (bottom) each cause leaf spots on asters. The spots start as pinpoint dark areas and enlarge irregularly or into a circular shape, sometimes with a yellow margin. The spots are hard to distinguish visually but can be controlled with many of the same fungicides. Prevent leaf wetting when possible.
Myrothecium & Bellis Alternaria Leaf Spots- Myrothecium roridum attacks many ornamentals creating leaf spots and stem rot. The fruiting bodies of the pathogen are very small, black and have a white fringe. They form in dead areas and can be in rings on leaf undersides or anywhere on dead stems. These have been greatly magnified. Alternaria leaf spot on Bellis appears as tan areas surrounded by dark brown to black. The disease is spread by splashing spores and overhead watering should be minimized to reduce this occurrence.