Question:
In spring, some of the flower buds on my peonies turn brown and fail to open. Why?Answer:
The browning of the peony buds is likely due to botrytis blight. Botrytis blight is a common fungal disease of peonies. The fungus Botrytis paeoniae attacks stems, leaves and flower buds. It is most common in cool, rainy weather.
Young shoots attacked by botrytis blight discolor at the base, wilt, and fall over. Affected flower buds turn brown and fail to open. The withered buds are later covered with a mass of gray, fuzzy fungal spores. Infected leaves develop large, irregularly shaped dark brown spots.
Botrytis fungi survive in debris left in the garden over winter. In spring, remove withered flower buds and spent flowers. In fall, cut off the peony stalks at ground level. Remove the plant debris from the garden and destroy it. If the peonies are growing in partial shade, move the plants to a sunnier location.