White fungus or mould attacking your garden plants is called sclerotinia. Sclerotinia will cause irreversible damage--such as rot--to hundreds of ornamental plants and vegetables afflicted with the fungus. When eliminating sclerotinia, many only treat the plants and not the soil. If you allow the white fungus to remain in the soil, the sclerotinia will continue to attack the plants year after year.
Wear a pair of gardening gloves and remove all plants--including their roots--that have the white fungus present. Place these plants in a burn pile or garbage bag. Do not compost the plants.
Scoop the surrounding soil with a garden shovel. Remove 5 to 6 inches of the soil. Place the soil inside the garbage bag. Scoop up any of the soil that was clinging to the infected plants that fell to the ground.
Replace the infected soil with fresh soil appropriate for your garden.
Provide adequate drainage for the soil. Poor drainage or an increase of moisture--such as heavy rainfall--will increase the chance of mould and fungus growth.
Plant the vegetation in a different area of the garden than it was planted the previous season. The mould can lay dormant in the soil for many years. Moving the plants every season will reduce the chance of awakening the fungus.
Lay garden plastic on the ground to act as a barrier to prevent the white fungus spores from germinating in the soil.
Remove weeds. Weeds are known hosts for a variety of pests, including white fungus. Removing them from your garden will reduce the risk of pests and diseases.