Question
Hey David

I live in St. Louis, MO (zone 5)I have 4 disease proned peony bushes. This year they have grown beautifully, they're about 3 feet tall already. They appear to be very healty however they develop black spots on the leaves then shrivel up and die before the end of the summer. My neighbor's bushes normally last thoughout the season and remain beautiful all summer long. I need to know how to treat the bushes that are already developing buds.  

Answer
It is most likely a fungal or bacterial leaf spot.  I would take off all the affected leaves and destroy them.  Then I would treat with a product made by Hi-Yield called "copper fungicide". The copper has activity against both fungi and bacteria.  You may need to re-treat in 7-10 days.  Then I would watch the new growth for symptoms of the disease and treat as necessary.  In the fall, cut all of the old plant material off and destroy.  The new growth next spring may need to be treated early in the season to prevent the disease from showing up.  I hope this helps.  Good Luck.