Re: Leaf spot
We feel that the leaf spot is spread by insects. The japanese beetles
spread it on roses and the aphids seem to spread it on the irises. Even your
garden tools can spread it. We have found that by keeping down the aphid
populations we have far fewer leaf spot problems. Also, June bugs spread
soft rot. Don has examined their mouths under the microscope and they had
Erwinia carotovora (soft rot) in them. Possibly they inject it into other
plants then after the soft rot breaks down the rhizome they eat them.