How to Treat a Soil-Borne Fungus

Remove plant residue when possible. In the fall, when your garden plants have died back, remove them from the garden space. Plant residue makes excellent compost and can be added to the soil, but it should be removed to a composting location to age and should not be returned to the garden soil until it has decomposed completely. This will prevent fungus from growing in the old plant matter and infecting new plants.

Remove dead plants that are infected with fungal disease. Do not put them in the compost bin where it can infect the compost. Instead put it in with the burnable waste and burn it.

Dig up affected plants, and replant them. Remove the affected soil and replace it with sterilized potting spoil. Use potting soil that is guaranteed to be free from pathogens.

Set up a sterilization chamber. Set up a heavy plastic in a tent over the contaminated soil and then put a heat lamp on the outside of the plastic to heat the soil. If you raise the temperature of the soil to above 100 degrees, the fungus will find it harder to survive.

Treat the outside of the plant with an anti-fungal agent like neem oil or fungicidal soap. This may help you save a plant that is newly infected.