Time to act:
Jun, Jul, Aug
Balling is triggered by cool, damp conditions, often in a partially shady site, where water-saturated outer petals fail to dry out before being scorched by the sun. The mushy plant tissue dries to form a stiff straightjacket around the petals, preventing the flower from opening. An invisible soft, slimy layer of mycelium then fuses the petals together. The problem is most acute on roses with a multitude of thin petals.
Apparently healthy rose buds develop and fatten but fail to open. They eventually wither or drop off.
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