I had a peonaflious that had rot on the base of the leaf. I treated it with Bayer Advanced All-in-One Rose and Flower Care. It stopped the rot and the rotten part dried up and I didnt lose the leaf even though it rotted about half way through the base! I actually planed on posting this on aroil-l tonight. here's what thier website says and how it works, you pour it ant the base and it gets absorbed from the roots and protects the plant from the inside out. Its three systemic products in one providing complete rose and flower care, with fertilizer, insect protection and disease control. * 3 systemic products in one
o Fertilizer - feeds and renews
o Insect control
o Disease control
* Protects against insects and diseases for up to 6 weeks
* No spraying. Just mix in a watering can and pour at plant base

How It Works:

Water moves the product down into the root zone where it is taken up & moved into the plant. The entire plant, even new growth, is fed and protected against insects and disease. Rain or watering cannot wash off this long-lasting systemic protection.

Kills:

Adelgids, Aphids, Black Vine Weevil Larvae, Black-spot, Japanese Beetles (adults), Lacebugs, Leaf Beetles (including Elm Leaf Beetles and Viburnum Leaf Beetles), Leafhoppers (including Glassy-winged Sharpshooters), Leafminers (including Holly Leafminers), Mealybugs, Psyllids, Powdery Mildew, Rust, Scales (including Armored Scale (suppression) and Soft Scale), Southern Blight, Thrips, Whiteflies

Here is a link that might be useful: here is thier website

I have used this product.
I really like it.
I was having trouble from all the rain we had this year, and then comes the fungus and bugs.
So I was to the point I was going to start pulling up all my plants they were getting so awful looking. Stunted growth and loss of color and brown spots etc everything had something.
A week to 10 days after I applied this my plants ALL perked up and started growing.
Too bad it now going into fall. :(
Bonnie

Dig it out, wash it well and cut out any rotted material. Sprinkle it with powdered sulfur (drug store or local ag coop store) especially the raw, cut areas. Let it dry in the shade for a day. Replant. The sulfur will help stop the rot, cauterizes the cuts to stop "bleeding" and will chase the bugs.

Unfortunately, help came way too far late. I had to throw the tuber out a few weeks ago; rot had reached the growth point and it all pretty much liquified in my hand.

Thanks for the posts though, everyone! :) Sad to have lost a gift (and what got me into the Amorph. species!), but at least it wasn't a rare species. I can probably get another one fairly cheap.

In the spring, Hurts Gardens on ebay sells the in blooming size for like $12.