I just walked over to some of my shrub roses and was shocked to see that black spot had attacked with the intention of taking off every leaf!
This summer has been ideal weather for every form of blight and fungus because of our high humidity and the onset of dew lasting from dust through mid morning. A wet leaf surface is required for these disease spores to invade the tissue, and in every 24-hour period the leaf surfaces have been wet longer than they have been dry.
For roses, the leaf loss as a result of black spot is a serious problem because that means less leaves to feed the plant going into dormancy. So I attacked the black spot! Daconil is a good fungicide for that purpose, but both upper and under sides of leaves must be sprayed. Again, I can’t stop the disease on infected leaves; I can only protect new leaves from becoming infected. Any leaves showing the symptoms will still fall off … and that’s the way it will be!
Dogwood shrub leaves are showing symptoms of anthracnose and what you will see there is a dark purplish round spot anywhere on the leaf surface. One spot soon becomes three and three becomes twelve and soon the leaves start to fall. This fungus will not kill the shrub but will give you a lot of mess to clean up. Daconill again is what I’d recommend to prevent the spread of this disease.
On large trees I am seeing leaf loss also, but it is not practical to try to spray a tree this late in the season.