Is anyone else still having this problem and did we ever come to a concensus on just what it is? These are not the fungus black spots discussed in the care section of this website. These are only on the undersides of the leaves unlike the fungus spots pictured in the care section. The affliction spreads at a steady pace usually moving from the bottom leaves toward the top. It is a year round problem. I keep wondering if it is connected to microscopic mites of some type, not the spider mites I've seen around here for years. Those and their webs are easy to spot. These are hard to find even with a lighted loop. These mites appear to have developed resistance to Kontos as I've had numerous outbreaks even though the collection has been on the higher concentration of Kontos two sometimes three times per week since last September. Nothing seems to control the black spots which I'm wondering if it's a virus? Plants eventually get weak, go into decline, struggle for about a year, and die. The problem is worse on plants in the house and greenhouse, not so prevalent on plants summered out in the garden, but it's showing up there too. I'm losing about 15 plants a year because of it and frankly I'm starting to consider sending my complete collection (100 plants) to the landfill and stick with roses and daylilies. This is becoming overwhelming. I started growing these exotic hibs in 2004 and didn't see this problem til maybe 3 years ago. Then I only had aphids to deal with, the good old days.
dave
