It does kill the daylillies just like Iris I only had 3 plants but they were 4 years old so good size clumps and they got the same look as the iris did I thought it can't be the same thing but when I pulled some of the foilage they pulled out of the ground just like the Iris bulbs with no roots.
As far as it not hurting the Rhizome because you don't see a hole or rot does not mean it is not harmed, the scorch kills the plant, it is a organism that has to have a host to live in the form of a insect (leaf hopper, Aphid) or other leaf peircing insect it feeds on the plant and then transmits it to another then another, I was told it is similar to the Dutch Elm disease that has destroyed much of the Chinese Elms, what it does is destroys the cells that transport the nutrients to the plant it basically starves to death.
Once again it has to have a host to survive that is why you need to destroy any plants that have it ,if you leave them in place and some may try to grow back again but when they do they will have the scorch growing with it and the cycle repeats the only way to get rid of it is to heat the bulbs above 110 degrees for multiple days and you would need a greenhouse or something to that effect to do it. That is why it is important to get rid of anything that you know is infected if left in place it will serve as a reservoir for further infection and it continues hopping from plant to plant. From what I was told the difficult part of this is determining what has it , there are plants that have not been infected long enough to know if they are infected yet so if left to long the insects will continue to transmit it.
I chose to remove anything that even looked like it had it, and dig and move anything that looked unaffected hoping that I got rid of all of the sick ones, I cut the foilage low on them hoping the leaf hoppers would chose other plants to feed on and leave the Iris alone ,it has been a few weeks since I got most of them moved and yesterday I was checking my field bed and 95% of what I replanted has started to root and re grow with know signs of Scorch but I found about 10 bulbs that showed no growth and no roots and I tossed them in the dumpster maybe Im a little paranoid but I would rather error on the safe side then let it get started again.I was told Merit will not kill the leaf hoppers they must be sprayed directly I tried a number of products from Home Depot (Sevin) is listed as one that says it will kill them but I think it must need to be in a higher concentrate than they sell because it did not work for me at all I am using a product called Demon and Talstar and those sprayed directly on them work within minutes. I hope you can get it under control it has certaintly opened my eyes.
