Roses are very susceptible to fungal diseases. Whilst you can cope with a bit of mildew a bud that fails to open is somehow more annoying. These buds had been hit by a lot of rain and a long period of humidity and nothing was going to help them.
- Try to water roses in the early morning so that any excess water on the leaves and blooms will evaporate quickly.
- Water the roots not the buds and leaves, it takes less water to do more good that way.
- Your roses will be happiest if you remember to mulch! mulch, mulch, mulch!
- Buds and flowers infected with botrytis will appear grayish-brown and shriveled. Prune and destroy diseased parts and keep the soil under the roses clean.
Bud blast on rhododendrons is a disease that produces black, bristle-like fruiting bodies on the surface of the bud. In spring they are dry, brown and covered with characteristic ‘bristles’ which prevent the flower from opening.