A disease of peonies - Peony Botrytis Blight – was one conversation at a friend’s dinner table last night. Because it does not often present a significant problem to peonies in this area, one of our keen gardening friends at that table suggested I ‘alert’ our customers to its presence and menace this season.
We hope this email reminds you to be on guard for this peony disease that appears quite widespread this growing season. We too have not escaped its presence and want to alert you of what to look for and how to keep your peonies as healthy as possible.
The long, cool and very wet start to summer was just the condition favouring the development of many fungus diseases. The botrytis fungus (and many other funguses for that matter) is commonly present in all soils where it is just waiting to proliferate when conditions are to its liking. Healthy plants can be untouched by the fungus, but weak or previously injured stems can provide a point of entry for the fungus to gain a foothold in the plant. Injury can be as simple as a bruised stem from a hoe or cultivator used to scuff up the soil in a weeding episode.
The two most noticeable visual symptoms of peony botrytis blight on early season peony plants are stems which have fallen over at ground level and decaying portions of these stems at ground level. At bloom time, some buds may turn brown and do not open.
The key is action NOW! Key to controlling this blight is not allowing it to spread in your gardens. This means dispose infected plant parts in the dump-bound garbage, not in your compost pile. Placing botrytis-affected plant parts in compost is creating a massive botrytis incubator – you don’t want to reapply the disease to your gardens next season!
While you are examining your peonies in mid to late season, keep in mind other diseases may be causing stem wilt or leaf discolorations such as spotting or larger areas of decay. Look for individual leaves with brown patches or whole stems that are ‘limp’. These are indicators that you should identify what disease is present before embarking on a remedy.
Below are four excellent university web sites on peony diseases and what to do about them. With your internet browser (e.g. Netscape or MS Explorer) open/launched, just click on each URL to go directly to each site. If this fails to work, copy and paste each address into your browser’s search window and you should get each fact sheet.
Click on each of the following for peony disease information.
http://www.ext.vt.edu/pubs/plantdiseasefs/450-602/450-602.pdf
http://www.extension.umn.edu/distribution/horticulture/DG1153.html
http://plantclinic.cornell.edu/FactSheets/botrytis/botrytis_peony.htm
http://plantclinic.cornell.edu/FactSheets/botrytis/botrytis_blight.htm
