Peony Leaf Spot Causes: Tips For Treating Spotted Peony Leaves

Peony Leaf Spot Causes: Tips For Treating Spotted Peony Leaves

By: Darcy Larum, Landscape Designer

Peonies are an old-fashioned favorite in the garden. Once a well-known harbinger of spring, in recent years new, longer blooming varieties of peony have been introduced by plant breeders. These hardworking horticulturists have also developed more disease resistant varieties of peony plants. In this article, we will discuss common afflictions that cause spots on peony leaves.

Why are My Peony Leaves Spotted?

Spotted peony leaves is usually an indicator of fungal disease. Once a fungal disease is present, there is very little that can be done to treat it. However, preventative measures can be taken to ensure that plants do not get fungal diseases. Preventative use of fungicides in early spring is one method. When using any product, it is important to follow all labeling instructions thoroughly.

Proper cleaning of garden tools and plant debris are also important steps in preventing disease infections. Pruners, shears, trowels, etc. should be cleaned with a solution of water and bleach, between each use to prevent the spread of disease from one plant to another.

Fungal disease spores can lay dormant in plant debris, such as fallen leaves and stems. Cleaning up and destroying this garden debris can help prevent the spread of disease. Fungal spores can also remain in the soil around infected plants. Overhead watering and rain can splash these spores back up onto plant tissues. Watering plants with a slow, light trickle, directly at the root zone can help prevent disease spread.

Diagnosing Peony Leaves with Spots

Here are the most common causes of spotted peony leaves:

Leaf Blotch – Also known as peony measles or peony red spot, this is a fungal disease caused by the pathogen Cladosporium paeoniae. Symptoms are red to purple colored blotches an inch (2.5 cm.) or larger on leaves, and the foliage may be curled or twisted near the spots. Red streaks may form on stems. This disease is most prevalent in mid to late summer.

Gray Mold – A fungal disease caused by Botrytis paeoniae, symptoms include brown to black spots on foliage and flower petals. As the disease progresses, flower buds may turn gray and fall off, and fluffy gray spores will appear on foliage and flowers. Gray mold disease is common in cool, wet weather.

Phytophthora Leaf Blight – This fungal disease is caused by the pathogen Phytophthora cactorum. Black leathery spots form on peony leaves and buds. New shoots and stems develop large, watery, black lesions. This disease is common in wet weather or heavy clay soil.

Foliar Nematodes – While not a fungal disease, insect infestation caused by the nematodes (Aphelenchoides spp.) result in wedge shaped yellow to purple spots on foliage. These spots form as wedges because the nematodes are confined to the wedge-shaped areas between major leaf veins. This pest problem is most common in late summer to fall.

Other causes of peony leaf spot are powdery mildew and the viral diseases peony ringspot, Le Moine disease, mosaic virus and leaf curl. There are no treatments for viral spots on peony leaves. Usually the plants must be dug up and destroyed to end the spread of infection.

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Solving Peony Problems

No Flowers - Improper Culture
There are many possible reasons why peonies fail to bloom. Some of the most common cultural reasons are:
1) Plants are too young. They need 3 or more years to mature.
2) Roots are planted too deeply. Be sure eyes are no more than 1 to 2 inches below soil or mulch.
3) The weather is too hot. In hot climate areas choose early blooming varieties.
4) The plant needs dividing. If the clump has been undisturbed for a decade or more, divide it.
5) Competition from shrub and tree roots. Move the plant to a location without dense tree roots.
6) A late spring frost has killed flower buds. Cover the plants with agricultural fleece to protect them when late frost is expected.
7) Waterlogging from too much rain. Move to a higher, better-drained location if this is a chronic problem.
8) Plants are undernourished. Sprinkle a handful of granular fertilizer around the plants.
9) Ground is too dry. Give plants 1 inch of water per week.
10) Too much shade. Move to a sunny or lightly shaded location.
11) Gophers, voles, or moles have harmed the roots. Control the animals.

Weak Flower Stems - Inferior Plants Deficient Soil Excess Shade
Weak stems that do not stand up well when the blossoms are out indicate either a weak stemmed variety, a phosphorus deficiency, or the plant is in too much shade. Fertilize with a balanced, high-phosphorus fertilizer. If the plant is in shade, move it to a sunny location. If the problem persists, you may have to either stake the flower stems or try another variety.

Ants - Ants on Stems
Ants feed on the sticky syrup covering the buds, but they do not cause any direct harm.

Flower Petals Eaten - Rose Chafer
Adult rose chafers are tan beetles with a reddish head, and about 1/2 inch long with spiny legs. They feed on peony flowers, sometimes ruining them completely. Hand pick them off the plants. Spray heavy infestations with pyrethrum. For long term control, scratch milky spore powder (Bacillus popilliae) into the soil to kill grubs.

Leaves And Flowers Discolored - Thrips
Flower thrips are slender, lemon yellow to brown, with 4 narrow, fringed wings. They move about very actively, like a bunch of animated exclamation points. The nymphs are wingless. They rasp at plant tissues with their tongues and lap up the sap. Brown spots on light colored flowers and red spots on darker flowers indicate thrips damage. Set out yellow sticky traps as early warning devices. As soon as thrips appear on the traps, check plants and spray with insecticidal soap every 3 days for 2 weeks. For more information see file on Dealing with Thrips.

Small Bumps On Leaves - Scale
Scale insects lurk beneath their rounded waxy shells, which are colored white, yellow, or brown to black, and are about 1/10-2/5 inch in diameter. The first sign of a scale attack is often discoloration of the upper leaf surface, followed by leaf drop, reduced growth, and stunted plants and obvious bumps along stems and branches. Heavy infestations kill plants. Some species excrete honeydew, which coats foliage and encourages ants and sooty mold growth. Scraped minor infestations off plant surfaces with a finger nail or a cotton swab dipped in rubbing alcohol. Spray heavily infested plants with a mixture of alcohol and insecticidal soap every 3 days for 2 weeks. For more information see file on Dealing with Scale.

Shoots Wilt and Collapse Leaves Spotted - Botrytis Blight
The most common disease of garden peonies is caused by a gray mold called botrytis. In spring when shoots are about 1 foot long, they may wilt suddenly and fall over. When pulled out or cut off below the ground, a brown or blackish rot appears at the base of the leaves and stem. Stalks just above ground level are covered with gray mold. Buds and opening flowers are also attacked. Remove and destroy infected plant parts. Put them into a plastic bag before discarding. Pull mulch away from crowns and don't wet their foliage when watering peonies. For more information see file on Dealing with Fungal Diseases.

Do you have a gardening question? Ask Nancy

A sick Peony Help

Hi have two Double pink. 4 yr old peonies/ Growing up against a row of Pyramid Cedars ( Neighbors)
One has very red/ shriveled leaves? and much smaller? than its sister Plant :( The other one has budds already. It is in a sunny location.I have looked for bugs can't see any Ideas anyone I love these babies>:) I am in Kelowna British Columbia canada Zone 6b (lake affect).

Could it be competition and leaf litter from the Cedars? Some trees or large shrubs can be very greedy, and get the lion's share of water and nutrients.
Did you have to cut out a lot of fine roots from the Cedars when you planted the Peonies?

Peonies like lot's of sun, infact, when planting these tuberous plants, it is importand that you add lot's of humus or well rotted animal manure to the planting hole as this allowes air, nutrients, helps hold some extra moisture around the greedy tubers, as you plant the large tubers, you need to have the top (crown) of the tuber JUST under the soil as they like the tuber to be baked in sun to help produce their beautiful flowers and floiage, never cut the foliage down after flowering, allow the foliage to die down and either remove it once shrivled and dead, cut it away or in cooler areas, lay it over the tuber area to protect the tuber from frost or very cold conditions. I like to add a compost mulch end of summer with a handful of multi purpse feed mixed into this mulch and make sure you dont forget to scarpe some mulch away in spring so the tuber is not buried too deep under the soil.
These plants are very greedy and mulching around the root area each year will help maintain some nutrients and water retention but dont ingrore a watering regime also as they need a good drink often.
My plants after about 2 years need a good plant support to help prevent damage if wind, heavy rain etc causes the flowering buds or open flowers to fall over being full of rain water, the foliage looks much nicer too if given support as it looks really nice even after all the flower buds have been removed once flowers have withered, to help the plant build up strength for next years flowers, I remove the dead flowers as I dont want the plant to produce seeds, this can weeken the plant and uses up a lot of energy, I'd rather have the energy going into the tuber for the following year and the making of larger tubers and root system to help stability with wind.
Hope this helps a bit and you enjoy many, many years of beautiful flowers, I have some Peonies that were here before we came and they must be about 50 years old by now. Maybe move the plants to a better area of garden would help too.

Red or pink leaves are normal on peony sprouts. Some varieties keep a reddish cast to their foliage all season. See photos below taken a few minutes ago, the young plant with very red shoots and the pair of mature plants, one with red shading on the foliage and the all-green variety behind it.

First: Are both plants the same variety? If not, you may have two double pinks that sprout and grow at different rates.
Second: Do both enjoy the same growing conditions? Same amount of sun, same drainage, same amount of impact from the cedars? Like WeeNel mentions, peonies grow much better with good sunlight. So, if the smaller one is in a shady site, it may have struggled in prior years and this spring it just doesn't have much energy to develop its new foliage. If that's the case, I'd move it now rather than lose it.
Third: Is this the first year you've experience this? I ask because peonies are fussy about the depth at which they are planted. They like the eyes/sprouting points to be 1.5-2" below the soil level. Plant them deeper and while they'll often live, they won't thrive and will be smaller, less robust and often won't bloom.

If these three questions don't provide clues, I'd take a leaf from the smaller plant to a good garden center to have them check for botrytis which is a fungus that tends to shrivel leaves and is particularly prevalent during wet springs.

You people have been most helpful. Thank you so much :) The peonies are.( Pink Peony. Paeonia lactiflora 'double pink ) This is what it states on the stick that came with the peony. The leaves are curled up on one. hmm. and it is much smaller. Yes they are the same plants exactly bought at the same time. But are blooming right now Not open yet but usually are gorgeous. I will wait til they go through their flowering .I will cut the flowers off. and let them do their thing Til' fall and transplant in a better location and hopefully they can have their way. instead of competing with those ( thirsty thieves)= Pyramid cedars. They are in a sunny location and summers here get very hot usually like a desert climate.
Diana_K said" Could it be competition and leaf litter from the Cedars? what do U mean by this. wouldn't leaf litter be giving the plant nutrients. This is an awesome question. I do not understand.

I am also afraid of burning things with fertilizer. I did this last year with some rose plants.

We certainly do have active aphids here as the plum trees new growth has curled up leaves. could be something else.But I will either cut off curled leaves on plum tree or. I live in The Okanagan valley" which has many orchards and vineyards. lots of over-use of pesticide here. many birds and good critters are coming back since the "new chemical laws were changed"

Does anyone have any idea where I could get my plum leaf question answered>? Its costly to spray and I have a Westhighland white terrier who cannot be near chemicals. They have the highest rate of bladder cancers.:(

I am sending a picture of my dog She is 13 yrs old. Her name is Tessa'
Thank you for any comments U have been most helpful
Michelle from sunny Kelowna, British Columbia canada

[email protected] very frustrating when you think there is something wrong with a plant and when you describe your problem we all take a different view of what we imagine so bare with us. As for the curled leaves, My Peonies are not yet in flower here in UK but, some of the foliage as it grows from a tight bud /ball, it starts off curly and as it grows and unfurls, they do look like they are curling up but in fact, they are UN-curling, I could be completely wrong by what you are describing though.

As for the competition from tree's, weeds or other growing plants, Peoney and many other flowering plants especially when they are tuberous or bulbs, don't like to be beside other greedy plants /trees who have much larger / stronger roots that when it rains or you offer any water / feed, these stronger growing plants / tree's will naturally be able to take up all the moisture /feed they require and the likes of flowering plants cant compete with this type of bed fellow.

As Mentioned before, a Peoney is a large tuberous plant and as it grows more each year so does the tuber underground increase in size, so it needs a good rich humus rich soil to sustain the requirements to help it grow those lovely large flower heads and the amount of flowering stems will also increase each year, the humus helps retain moisture when given a watering or rain, and helps air and feeds the tuber too, also they dont like to be burried way under the soil, allow the top of the tuber to be JUST under the top soil. I would leave any transplanting till ALL the foliage has died down at the end of summer so it has less stress to deal with and time to recover and settle down before new growth the next spring.

As regards burning plants with Fertilizers, that normally only happens when the instructions have been miss read and there has been too strong a dosage watered onto the plant, or onto the soil and dug in or watered into the soil, so next time make sure you read all the do's and don't and follow the dosage to the T, it is very easy to over do feeds / fertilizers so your not alone when you worry about this but if in doubt, use half the amount given on the package / bottle as this will do no harm and when your happy the plant is doing good, you can add the next half dose say a week or two later.

Cant help you with fungside for bugs as I try never to use them but there are times when no mater what you use, there's a time when you have to go to the chemical route, I would start spraying with dish washing soap liquid and make this into a watered down liquid to spray onto the plants /shrubs/ tree's etc for the type of things like aphids ( green, white fly ) these cause a sticky substance on the leaves that then attract other insects to feed on this stick stuff called honey fungus, the dish soap kills off these tiny flies IF you keep up the spraying every few days. try this before you use chemicals if you don't like to use them.

Type of Sample Needed for Diagnosis and Confirmation

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if you plant has this disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents. If your sample is from outside of Iowa please do not submit it to the Plant & Insect Diagnostic Clinic without contacting us

Peony flower with a case of leaf blotch

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