Botrytis can infect stems and flowers, including stubs left from pruning or flower removal. Infected tissues are usually covered with a fuzzy, gray-brown growth. Infected flower buds may not open, and can show sunken, smooth, grayish spots on the bud and flower stem. Sunken, dead areas may develop on the canes. Infection is worst during cool, wet weather.

Management Options

Non-Chemical Management

Remove all infected portions of plants as soon as the first symptoms appear. This reduces spread of the disease.
Clean up and destroy all dead plant materials.
Increase air circulation in plantings by proper spacing and pruning.
Avoid overhead watering.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

Use as a foliar spray, but focus on cultural controls.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

Bonide Fung-onil Multi-Purpose Fungicide Conc.
Active ingredient: chlorothalonil | EPA reg no: 60063-9-4
Bonide Infuse Systemic Disease Control Lawn & Landscape
Active ingredient: thiophanate methyl | EPA reg no: 53883-183-4
GardenTech Daconil Fungicide Conc
Active ingredient: chlorothalonil | EPA reg no: 67572-82-71004
Ortho Max Garden Disease Control Conc
Active ingredient: chlorothalonil | EPA reg no: 239-2522
This list may not include all products registered for this use.

Images

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Caption: Botrytis on rose blossom Photo by: R.S. Byther
Caption: Botrytis on rose canes Photo by: R.S. Byther

WSU Extension

Hortsense