“A bed of my hostas suddenly wilted and died this week. I always thought that hostas were trouble free. What is this, and what can I do to prevent future problems with one of my favorite plants?”
— Abigail Jefferson, Glencoe
Hostas generally are care-free plants, so when a planting crashes at this time of year, it warrants a close look. Early in the spring, anthracnose was attacking some hosta plants, which looks considerably different than the issue you describe.
More Top Picks Best Amazon Prime Day Corsair Gaming Deals 2026
You may be having a problem with southern blight, based on your description. Southern blight (Pellicularia rolfsii, Sclerotium delphinii and Sclerotium rolfsii), commonly called crown rot, has been a sporadic problem at the Chicago Botanic Garden, and the staff has been taking steps control it.
As the name implies, it is a disease that is common in the southern states and said to be rare in Illinois. It is a fungal disease that affects herbaceous plants and some woody plants, and results in plant collapse and death.
Southern blight is favored by very hot (high 80s and 90s in Fahrenheit degrees) and humid, wet weather. The pathogen can remain viable in soil for three to five years. It affects many host plants and seems to favor hostas here.
Since it is an uncommon disease in this region, gardeners need to look for it when plants crash unexpectedly in the garden, and take action to avoid spreading it further throughout the garden.
It is relatively easy to identify this disease in the late stages — look for wilting plants with yellowing leaves that collapse and die. The key identifying characteristics are the presence of white, fuzzy mycelium (the vegetative part of a fungus, consisting of a network of fine white filaments) at the center of the plant’s crown, near the soil line.
Also, look for sclerotia, which are small, round “seed-like” growths that are white, reddish tan or brown. If you see the sclerotia at the base of your hostas, then you most likely have southern blight affecting them.
Plants in the vicinity and downslope from these plants could be infected but not yet showing symptoms, so will need to be monitored going forward. Moving water will spread this disease, along with contaminated tools, plants, soil, gloves and shoes.
Promptly remove any infected plants along with the soil around them. Try to remove the soil to a depth of 8 inches and 6 inches away from the plant. Place the plants and soil into a heavy-duty trash bag and put it in the garbage; this debris should not be placed in your compost pile.
Do not do this work during wet conditions, and be careful to contain the soil and plant debris that can spread the disease. Bring in fresh soil to fill any resulting low spots. It is important to sanitize any garden equipment used to do this work. I use Lysol disinfectant spray to sanitize my tools when needed.
Other good practices to help contain this disease include the following: avoid or minimize walking through the area that may have southern blight; do not mulch, because the mulch helps create favorable conditions for the disease; avoid watering or minimize watering to avoid runoff; and do not transplant plants from the area that may be infected with southern blight to other parts of your garden.
There are fungicides that can be applied to help protect your plants. If you are able to eradicate the disease from your hosta bed, then divide the remaining ones or purchase new plants to fill the holes. If the disease persists, then you may need to replace all the hostas with plants such as goatsbeard, maidenhair fern, royal fern or hellebore, which show resistance to southern blight.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at [email protected]. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.