White fungal spots on the leaves of a pansy causes the plant to look unhealthy and its blossoms don't last as long. If left untreated, the fungus can kill the plant. Leaf spot diseases occur in wet, warm areas of the garden, where it is easier for them to thrive.
Leaf spot diseases and powdery mildew are two of the fungal sources of white spots on pansy leaves. The fungus will begin as small, white spore spots on the tops or undersides of the pansy's leaves. These produce spores that allow the fungi to reproduce and spread throughout the garden and onto other plants. As the fungus matures, it will spread to cover the entire leaf, leading to numerous health problems for the pansy.
Fungal leaf spot diseases and powdery mildew attack and kill pansy leaves as they mature. The progression of these diseases can lead to the death of the flower. The disease prevents the pansy from absorbing sunlight during the day by covering the leaves, which stops photosynthesis, and sapping nutrients from the plant to support its own growth. Fungi can kill, defoliate and kill pansies.
Keep the soil around pansies free of standing water, as this is a growth spot for fungi that cause the white spots to appear on the leaves. Dig channels in the soil to drain water away, if necessary. Pinch off severely affected leaves, especially those that have turned yellow or brown and started curling. Remove any fallen leaves from around the base of the pansy, as these act as hosts for the fungi.
A fungicide spray helps kill spores on the pansy and prevents spores from maturing. Additionally, fungicides help control the spread of the fungal disease between pansies and other garden shrubs, flowers and even trees, where diseases like powdery mildew cause additional health problems. Apply a spray fungicide to the pansies and surrounding plants according to the directions to kill the fungal spores that may be present but not mature enough to produce spots.