How do I prevent Botrytis/Gray Mold from spreading on my cut peonies? I have...

Asked June 9, 2015, 1:31 PM EDT

How do I prevent Botrytis/Gray Mold from spreading on my cut peonies? I have around 2000 cut flowers in water that are in cold storage. They are stored at 40 degrees Fahrenheit. What types of fungicide or preventative measures can I use in order to prevent Botrytis growing on the cut flowers?

Fairfield County Ohio cut flowers botrytis horticulture

1 Response

Hello -

There are several management practices that can help limit the incidence of Botrytis on cut peonies. Botrytis spores require a film of water to germinate and cause infection - which can occur on stems, leaves, buds, etc. Sanitation and keeping flower petals and foliage dry is key to prevention. A quick overview of Botrytis can be found here: http://ohioline.osu.edu/hyg-fact/3000/pdf/3070.pdf. Some things you can do to prevent botrytis:

  • Limit standing water on foliage, petals, buds, etc. Whenever possible, allow cut stems and flowers to dry before storing them in cooler.
  • Inspect all plants for signs of Botrytis spores before storing and discard any plant material with visible symptoms.
  • Sanitize cutting tools, surfaces, etc. to prevent spread
  • Maintain proper temperature and humidity levels in the cooler to prevent condensation. Condensation on the buds, petals, leaves occurs when warm air cools and forms water droplets on cool surfaces. Opening and closing cooler doors allows warm air to enter and increases the likelihood of condensation forming.

There are several products labeled for use in postharvest of cut flowers to minimize botrytis - these include Phyton 27 and Rhapsody.

Phyton is a copper-based product and can be used on cut flowers as a spray or a dip. Because a rate for peony is not specifically on the label, you would want to try the lowest rate on a few plants to make sure there are no adverse effects such as phytotoxicity: http://phytoncorp.com/wp-content/downloads/P27_US_Label_2010.pdf

Rhapsody label: http://chippersinc.com/files/8513/4772/0691/Rhapsody.pdf

This is also an excellent resource on cut flowers that you might be interested in having: http://ucanr.edu/datastoreFiles/234-1906.pdf


I hope that some of this information is helpful! Please let me know if you have additional questions or need further assistance!