How to Cure Crown Rot on Foxgloves

The spots on a foxglove are called "honey guides" because they point the way to the nectar.

Foxglove is an herbaceous biennial plant that is grown for its dangling tubular flowers. It is an attractant for hummingbirds, butterflies and pollinators. Foxglove spends its first year as a rosette which will overwinter and then flower the following year. Foxgloves will reseed themselves and most gardeners find that there are foxgloves or digitalis popping up in the same areas year after year. Crown rot is common in the south and areas with hot, humid weather. It stems from a fungus called Sclerotium rolfsii which attacks ornamental plants. It is nearly always fatal and there is no cure but there are preventative techniques.

Things You'll Need

• Magnifying glass
• Shovel
• Water bottle with 10 percent bleach spray
• Potting soil
• Shagnum peat moss
• Fungicide
• Pot
• Sulfur
• Moisture meter
• Water

Instructions

1. Identify the disease before you take drastic measures. The fungus causes the leaves to yellow and wilt. The base becomes mushy and with up close observation you will find fluffy white web or threads of the fungal mycelium. Use a magnifying glass at the base of a leaf to see the mustard yellow round fruiting bodies called sclerotia.

2. Remove the infected plant. Attempting a cure is impossible in the bed because you cannot control all the conditions. Dig up the plant and remove as much soil adhering to the roots as possible. Spray your shovel with a bleach solution to kill the fungus. Make a mix of 30 percent potting soil and the rest sphagnum moss and mix in a fungicide at the rate recommended on the package.

3. Dust the roots of the infected foxglove with powdered sulfur. Be careful not to inhale it. Pot the foxglove in the soil and moss mixture. Push the stem of a moisture meter into the pot and water slowly until it registers just above "dry." Keep the meter in and only water when the soil registers that it is "dry." Water only the soil and do not get any water on the leaves or stem of the foxglove.

4. Prevent crown rot by mulching around the foxglove to protect it from the heat. Water sparingly when the air is damp and warm. Avoid splashing water onto the plant as the fungus may be living in the soil and can travel in this manner.

5. Plant foxgloves in semi-shady areas to prevent the plant from overheating. Place them in well-drained soil and do not overcrowd them in a bed or they will be overcome by the humidity. Enhance air flow wherever possible. The best way to control crown rot is to choose resistant plants. Consult your county extension service for information on which plants might be suitable for your yard.

References

• "The Toronto Sun"; Falling for Foxglove; Janet Davis
• "Iowa State University Sustainable Urban Landscapes"; Crown Rot- A Serious Disease of Hosta and Other Ornamentals; Brooke Edmunds, Mark Gleason; February, 2000