cure for botrytis blight on my roses?

Answer 1

MASTER GARDENER TO THE RESCUE

Who told you your Rose has botrytis blight? I'll bet you a new Rose bush (installed) that you do NOT have botrytis blight. It just doesn't do Roses. I bet all you have is some powdery mildue?
Botrytis rot, or gray mold attacts friuts and veggies & is not know to go after woodie plants, like the Rose. Commonly affected crops include strawberries, lettuce, squash, melons, beans, peas and an occational artichoke, but seldom a Rose.
Damp areas near the ground turn leaves, flowers and green fruit turn brown & develop a gray or brown fuzzy growth of fungal spores.
Botryis cinerea, survives in decaying plant material in the ground and usually infests only the plant parts nearist the ground.
Just to make you happy, lets say your Rose has it.

Avoid nitrogen fertilizer. Good ventilation is a must & nitrogen will encourage growth stopping air flow. Remove infested fruit, like bunches of grapes. (you didn't say if your Rose had any grapes growing on it, did you?)
Clear away infected foliage, plant your next crop of Roses in a raised bed and use furrow irrigation. Stake any low hanging Rose buds to avoid soil contact. Prop heavy ripening fruit or Rose buds with an old strawberry basket. Keep the ground and area around the infected plant clear of all debris. Infected plant materials should be disposed of well, so not to allow spores to spread. Keep the plants as dry as possible & treat as you would for powdery mildew because that is what you really have.

Answer 2

You can indeed have botrytis on your roses. Botrytis is typically found in areas that are high in humidity, so if it was humid in your area, you may have had the disease. In order to reduce incidence of disease, you should reduce the humidity around your plants by pruning your roses to allow more air flow through the plants, modify the watering schedule around the plants to decrease humidity, and don't put down too much mulch or other ground cover under your roses as mulch can also increase humidity. You would also want to remove infected debris and cut off any infected plant parts. In order for disease to occur, a pathogen, susceptible host, and conducive environment must be present. If you remove any of those components, you will no longer have conducive conditions for disease development. This holds for ANY disease!!

Answer 3

Hi Doc, welcome back.

If your rose has white/grey fuzzy looking patches, Doc was correct suspecting powdery mildew. My cure (that worked) is fresh coffee grounds (cheapest you can buy, roses don't care) and beer (also cheapest). Sprinkle at least a pound of coffee per rose bush around them and then add beer...2 cans per bush. Your roses will love you.