The peony is one of the most popular spring flowers. It is a showy and generally hearty perennial that doesn’t require much care. It has large showy blossoms that come in soft rosy pink, deep red, and white.
Peonies are living plants, and like anything that lives they are susceptible to forms of infections and viruses, white mold, viruses, and wilt are common peony diseases. When planted properly and given proper growing conditions, the peony can be grown almost disease-free.
However, when the weather is more wet, rainy, and humid for a period of time the plants will suffer. These are some ways to check for diseases if your peony plants are looking wilted or their growth seems to be stunted.
Diseases of Peony’s
Like any flower, peonies can become diseased also. If planted in a site where there is not enough sun, water drainage, and proper planting that includes spacing for air circulation and proper watering they will become susceptible to disease.
Check the base of your plant, and if the base looks good but the shoots are wilting it may have what’s called Verticillium Albo-Atrum, a soil-born fungus and one that is almost impossible to get rid of.
Cut off a piece of the stem and check the cross-section to see if it is brown (it shouldn’t be) this is the plant’s self-watering system. If it is checked with your local county extension office (County Dept. of Forestry) you will want to make sure before removing and discarding your plants.
The more common one you may expect to encounter, especially if the spring has been unusually cool and wet is a fungus called Botrytis Blight, or White Mold (called Sclerotinia Sclerotiorum).
White mold is a fluffy white mycelium that generally appears under humid conditions. It is a soil-inhabiting fungus, that is impossible to remove and your peony plants will need to be removed and replaced with nonsusceptible ones. Do not replant with peonies.
It is extremely hard to stop this disease since it is a soil-borne fungus. Replacing and planting plants farther apart to allow for air circulation, watering only at their bases in midday will help to reduce the infection.
Botrytis Blight symptoms include flower buds having brown spots, as well as the leaves, are having irregularly shaped spots. The flower buds or leaves of peony tend to covered with a wide area of gray fuzzy fungal spores. Botrytis will also show up when the weather has been a cool wet spring and summer.
The gray mold will cause unopened buds not to open and will spread quickly to open flowering buds. The infection will spread down the stems causing a brown or tan discoloration. The infected petals will drop off into the leaves and cause the entire plant to become damaged.
This fungus will cause the stems to rot on not only your peonies but other herbaceous plants in your garden as well. White Mold will cause a portion or sometimes the entire plant to wilt. The infected part of the stem will become dry and stringy and tan in color. If the weather conditions are humid a fluffy white mold will appear.
To diagnose this, slice the stem lengthwise and check for signs of irregular sizes of hard black sclerotic that will be inside the tan area of the stem. Sclerotinia is a soil-inhabiting fungus that is also nearly impossible to remove. Because it has the overwintering structure it can last in the soil for years.
Shows in the forms of ring spots, mosaic, leaf curls, and or elongation. If your plant has a virus, the leaves will be light and dark green in color, stringy and curly. They will also have a reduction in growth and will be less vigorous.
They will however continue to grow and bloom as usual except they will have a strange pattern on their leaves. No treatment is recommended for this but if it becomes severe remove and discards the plant.
There are fungicides available to treat wilt and whit mold but nothing will cure it. In the fall cut back your peonies and in early spring when the red shoots first start to appear start to treat the new shoots then. Treat the stems and buds at the beginning of the growing season to help prevent infestation.
How To Prevent Peony’s Diseases
It is hard to stop the diseases after they appear, however you can greatly reduce the infections. Remove any spent flowers or blooms, buds, leaves, and or stems. Do this after the morning dew has dried this will prevent water from any wet plants getting on healthy ones. When cutting off infected leaves and stems, clean your pruner with a 10% Bleach Solution or with 70% Regular Rubbing Alcohol.
Always clean you’re your tools before and after cutting off the diseased parts of any plant and before you prune the next one to prevent transfer. Carefully dispose of the infected parts, Do Not Place them in a Compost Bin or Pile. Good sanitation is important when your plants have been infected.
In the fall, you should cut back those diseased plants just below or to the ground. Then add some well-composted organic material as a mulch to the soil.
Fungicides have a limited effect against blights but applying Copper Sulfate, when it’s applied early enough the in spring when the shoots first emerge and reach about 6 inches tall will protect them. Spray all the plant parts to completely wet the foliage and soil. Remember to read and follow the manufactures’ instructions.
Prevent Powdery Mildew
We have issues sometimes where our peonies will get powdery mildew in really bad conditions. I have been trying an experiment now for putting cinnamon around the soil. For your information, fungus hates cinnamon so it can help to repel the powdery mildew away.
You can get a bottle of cinnamon and shake it around the soil surface. Powdery mildew is growing so quickly and you need to apply the cinnamon at the time before these diseases are attacking your peonies.
I normally apply this when the peonies are a lot smaller but it won’t hurt them and this should help to ward off powdery mildew.
Ants and Wasps
Another thing I wanted to talk about is why ants and wasps like to crawl on the peonies. The reason is the peony flowers need the wasps and ants to crawl across them to help open the flowers up. So that’s the reason why ants crawl on the peony buds when they get larger because the peony flower needs them to open the flowers up.
However, if you see the ants are crawling on your other plants, then that can be a bad thing because they could be bringing aphids. but when they’re crying on the peony
Here is the video for peony disease management. You may want to take a look.