Crown Rot in My Hostas

Asked August 14, 2017, 9:51 PM EDT

I am certain that what I have going on is Sclerotium Rolfsii, Crown Rot: Bottom leaves falling off,Mycelium and Sclerotia present. I removed one hosta and dug out the soil and replaced soil. Will drenching the soil with boiling water help to sterilize it and kill sclerotia? I have 3 other hostas nearby which are infected. I have removed mulch, mycelium, sclerotia and rotting bottom leaves. There is a lot of healthy plant left. Do I really have to bite the bullet and dig them up and discard them as I did the first one? All infected hosta are surrounded by cement landscape blocks. The fungus would need to travel over the cement blocks, across cedar chips (6-8') to reach other hosta beds if traveling across the ground. I am now aware of sanitizing and quarantine needs. Stupid question, but would the Shaklee product "Basic G" solution sprayed onto base of leaves and surrounding soil do anything to help? Essentially i am asking if there is any way to "disinfect" and save a plant which has been attacked by the fungus. What do you think of the treatment of digging up the plant, soaking roots with hot water and bleach (10 parts water to 1 part bleach) and replanting in new soil?
Also, does spraying plant and soil with peroxide work? Can I use undiluted 3% peroxide? If dilution is recommended, how much? Thanks, Kay Taylor

Ramsey County Minnesota

3 Responses
The most effective treatment is a fungicide.
Fungal spores are hard to kill and travel by air as well as water. Southern Blight can pop up at random. With regards to decontamination.
Basic G is an effective
sanitizer but not as effective as bleach. Bleach is also more damaging. It makes sense to start with Basic G. Trying to sanitize the soil with a hydrogen peroxide is not practical and probably not possible, the soil volume is too great and the soil will inactivate the soil before it kills the fungus. The same is true for treating the soil with boiling water, the volume of soil will cool the water before enough time has passed to heat treat the soil.

Bleach treatment works if the infection is not in all parts of the plant.

Hope this is helpful. I appreciate trying to save your hosta but the most important thing is to prevent southern blight from taking hold in your garden.

FUNGICIDE: I have fungicide on order, expected Sept. 6. Online discussions talk about "drenching' the plants. Does this mean the leaves and the soil? Sounds like pouring from a pail... Any advice on specifics of 'drenching?'

BLEACH: Meanwhile, I have been using 1/10 bleach/water in a spray bottle, spraying soil and base of petiole, but not the leaf. How often can I, should I spray this? Really did not stop more and more getting affected, but I was out of town for 4 days. I sprayed again when I got back home, then after a couple of days decided to remove the whole plant and the soil around them.
Today I decided to try to keep the 2 big Sum and Substance I dug up yesterday. I cut off all affected parts, scraped away most of the soil on the root ball and put in a plastic tub, sprayed soil and petioles with bleach solution again. Will quarantine until fungicide arrives. Have been very careful about sanitation through this process.

Drenching is most often done for trees but the protocol is the same, dosage will be different. Follow the instructions that come with the fungicide. These give the best results and the label instructions are legally binding. Use care to avoid exposing yourself to fungicide. Be sure to wear safety glasses and gloves.
Here is a step by step guide to drenching the soil.
Bleach is caustic and does cause tissue damage and using may damage the outer layer of the hostas opening it up to more infection. I agree with this writer about the problems with using bleach as a disinfectant. I don't think one can kill the fungus with bleach without killing the leaf tissue. Leaf tissue is more fragile than fungal growth.
Suggestions on how to treat fungal infections with a soil drench.