Rose Blooms Turning Rusty Brown: Rain Damage vs. Botrytis Blight

Reg's roses opened beautifully but turned rusty-brown from the edges inward within a day. Photos showed classic symptoms. Jay's initial diagnosis: rain damage (prolonged wetness causes petal browning). He also suggested fertilizing with 10-10-10 or weekly Miracle-Gro for roses.

When Reg confirmed no excess rain and regular fertilizing, Jay offered a second diagnosis: Botrytis blight (gray mold). This fungus thrives in warm days/cool nights, causing flowers to brown and fail to open fully.

Action Steps

1. Apply a rose fungicide labeled for Botrytis.
2. Check watering: underwatering also accelerates petal browning.
3. Improve air circulation via pruning.
4. Remove and destroy affected blooms to reduce spores.

Note: Yellow leaves often indicate water stress (too much or too little) rather than disease.