Aster yellows (phytoplasma-like organisms)

[bigdaddyscondition]

I recently acquired more experience with this disease than I ever cared for, specifically in my Wright Echeveria hybrid, 'Pappy's Rose'. Some basic research and discussion with the Wrights at Wright Nursery gave me some tools to deal with the infection, and I have saved some plants. What seemed to work for me was heat treatment by immersion of the severed rosette and stem in tap water at exactly 105 degrees F. for 30 minutes. Any hotter will destroy the plant, I was told. I've repotted about 5 rosettes (admittedly none showed stigmata of infection, but were grouped with or shared a stem with frankly infected rosettes) treated this way, and they appear healthy and disease-free. Agri-Mycin, an agricultural preparation of the old aminoglycoside antibiotic streptomycin recommended to me, did not work. The four yellowed, diseased plants pictured below were treated with two foliar and soil drenches of Agri-Mycin solution four weeks apart, with no discernible improvement. These plants, along with the soil they're in, are headed for a plastic bag and disposal. Another photo shows the same plants at an earlier stage of infection, about 4 months ago.

The pathogen is a poorly defined microbe vaguely called phytoplasma-like organism (previously called mycoplasma). Its sole vector is the aster leafhopper. The agricultural extension resources I've consulted say there is no antimicrobial effective against this pathogen.