What’s Eating My Peony? 7 Peony Pests to Watch for
Peonies will soon awaken for their spring and early summer bloom spectacle. While they’re usually problem-free, they aren’t immune to common garden pests. If you spot signs of stress on your floriferous beauties, scout for the most likely culprits. Gardening expert Katherine Rowe explores peony pests and how to best treat and prevent them.
Contents
Peonies look so scrumptious that it’s hard to believe pests don’t devour the decadent blooms more often. While peonies are mostly pest-free, common garden invaders do affect them from time to time.
You may see nibble damage from deer or rabbits early on when shoots and buds are tender. But, they seldom kill the plant. You’ll likely spot ants, which are totally harmless, drawn to the nectar of the buds. A few other common sap-sucking insects and nematodes cause the most damage.
With regular scouting on a stroll through the garden, spotting signs of pest damage early is the best defense. Ensuring the best cultural conditions for peonies offers a strong foundation for overall health. It’s always a good idea to diversify plantings to attract beneficial insects. Natural predators like lacewings, hoverflies, and ladybugs are the first line of defense as they prey on common pests. Here, we’ll look at pests most likely to impact peonies, as well as how to prevent and treat them.
Aphids
Aphids reproduce quickly and congregate in numbers on the undersides of leaves. They’re sap-sucking insects that feed on plant tissues, preferring new growth like tender shoots and leaves. They also damage buds and blooms with their concentrated feeding.
Aphids are pear-shaped and soft-bodied in light yellow, green, pink, brown, or black. You’ll spot them in groups, and they leave behind a sugary “honeydew” waste. The sticky substance can lead to black, sooty mold, which is unattractive but not as harmful. Over time, it builds up and obstructs photosynthesis. It’s a good indicator that a sap-sucker is present and is attributable to a few common peony pests.
Aphids can stress plants in large populations. They’re also vectors for fungal spores and pathogens. They spread diseases and viruses as they travel between plants, weakening them as they go. Peonies may show curled, yellowing foliage and stunted growth in an aphid infestation. Leaf spot, mottling, and distortion may follow as signs of disease.
To prevent aphids, water consistently to achieve evenly moist soil. They gravitate toward drought-stressed specimens over healthy, well-watered ones. Grow an array of blooming plants to draw a variety of insects for natural pest control.
Treatment
Fortunately, there are a few treatment options for aphids. If you spot aphids or their honeydew, try spraying the peony with a strong stream of water early in the day. The idea is to displace the insects from the stems and leaves (taking care not to blast the plant). Sap-sucking insects have piercing mouthparts, and the spray is meant to detach the mouthparts from their bodies. Doing so in the morning minimizes daily nibble damage but also allows leaves to dry in the day’s sun and breeze, minimizing damp conditions that cause fungal problems like powdery mildew.
You may also prune off impacted stems or leaves if the population is small and limited to a certain section. Effective for larger outbreaks are horticultural soaps and oils like neem. Plant-based, organic insecticidal oils include garlic, clove, rosemary, mint, and cinnamon oils. These treatments affect all insects, including pollinators and beneficial predators. The time of day and application directions are essential in the application.
Diatomaceous earth dusted over leaves and surrounding soil may lessen the spread. The powder creates a sharp surface that damages any soft-bodied insects.
Thrips
Thrips join aphids as sap-sucking insects. The tiny pests feed on petals and foliar tissues and can transmit viruses. They have long, slender bodies, and adults have fringed wings. They range from translucent white to yellow, brown, and black. There are thousands of species of thrips, and not all are harmful. Some feed on aphids and mites as natural pest managers. If you don’t see any damage, hold off on treatment.
When thrips are a problem, the petals develop white spots or distort. Leaves become papery, silvery, and stippled.
To prevent thrips on peonies, avoid overly dry situations, aiming for evenly moist soils. Parasitic wasps, mites, and green lacewings prey on thrips.
Treatment
If you aren’t sure you’re dealing with thrips, gently shake stems over a piece of white paper and look for dark spots (dropped thrips). Clip and dispose of damaged sections.
Neem and horticultural soaps treat outbreaks through coating all surfaces of leaves and stems. The organic treatment Spinosad, derived from a bacteria, disrupts their feeding to kill the insect.
Scale
Scale join their fellow sap-sucking garden pests as they pierce tissues to feed. They appear as black, gray, or silvery splotches underneath leaves and along stems. As with aphids, they leave a sticky residue in their wake.
Scale are mobile in the nymph stage, but most adults become stationary, sticking to leaves and stems to feed in the same spot. The good news is that adults don’t move from plant to plant (with the exception of male armored scale and crawlers).
In heavy infestations, peony leaves turn yellow before wilting and dropping, and stems die back. New growth becomes stunted or deformed.
To prevent scale, water regularly and rinse dusty leaves. They flock to dry, gritty situations.
Treatment
When possible and in cases of severe damage, remove impacted areas. For very small numbers, tackle adult scales by hand using a cotton swab dipped in rubbing alcohol. A soft toothbrush and soapy water also help to detach them, though these techniques likely aren’t feasible in the scope of the garden. Soaps and oils are effective in controlling nymph populations.
Nematodes
Foliar nematodes are slender roundworms that are difficult to see with the naked eye. The peony pests damage the upper growth and spread quickly. The first sign of foliar nematodes is yellow-brown lesions on the leaves between veins. These spots start on the lowest leaves and work their way up. They’ll eventually cover the entire leaf, which dries and drops prematurely.
Foliar nematodes climb (or swim) up stems after rain or watering. They use the water channel to travel up and enter the leaves for feeding. Their damage may kill the peony, and the initial lesions and outward signs mimic other fungal diseases, masking the true source.
Nematodes overwinter in the soil and debris from affected specimens. Good garden cleanup around peonies is a best practice. Mulching prevents water from splashing onto stems and leaves, lessening access for nematodes. Water is at the soil level, whether by hand, drip irrigation, or soaker hoses.
Treatment
Because nematodes spread readily and dwell for years in debris, remove and discard severely infected plants and the surrounding surface soil. Dispose of them away from the garden and compost pile.
Insecticidal soap may help as a treatment. In severe cases, spray surrounding plants, too, to catch nematodes before they enter the tissues of otherwise healthy selections.
Mealybugs
Mealybugs are soft-bodied pests with waxy, white, and cottony fibrous bodies. They move slowly and group together on the undersides of leaves, along veins, and in joints on stems.
When scouting, you’ll see the insect along with yellowing, wilting, stunted leaves, and general decline. With piercing mouthparts, mealybugs feed on sap and lay eggs in cellular tissues. The larvae feed as they hatch and continue the cycle.
Mealybugs leave behind the signature sticky honeydew and the telltale sooty mold that develops in humid conditions. Early infestations are easy to control, but if not caught, they’re challenging to get rid of entirely.
To prevent mealybugs, aim for consistent moisture during the growing season and a site with good sun exposure (though most peonies enjoy afternoon shade protection in intense summer sun and heat). Avoid applying too much fertilizer, as many peony pests feed on tender new growth with high nitrogen levels (excess fertilizer promotes both).
Treatment
Use the hose-stream of water technique to dislodge the insects. The cotton swab dipped in isopropyl alcohol for wiping the stems and leaves may be doable on a single specimen. It instantly reduces small populations. Horticultural soap or neem oil on both sides of the leaves mitigates outbreaks.
Bulb Mites
Peonies grow from tubers (fleshy, starchy enlarged root structures) where roots and shoots grow from bud “eyes.” Bulb mites are a peony pest that impacts the tuber. When the mites enter the bulb to feed, they cause weakness and allow exposure to fungal problems like rot. The tubers then become nonviable with extensive damage.
Bulb mites are milky white little rounds with short brown legs. They cluster to feed and occur in tubers in storage and the ground. Upper growth diminishes, decays, or fails to appear with bulb mites and their host of problems beneath the soil surface.
Treatment
The best way to prevent and control bulb mites in peonies is to purchase tubers from a reputable grower. If storing tubers over the winter, take care to avoid injuring the bulb when lifting. Inspect the tubers, especially when bringing them out of storage, for overall health, and toss any that are soft, mushy, or damaged.
Hoplia Beetles
Hoplia beetles feed on peony blooms, creating holes in the petals and damaging early buds and flowers. While they don’t eat the leaves, stems, or roots, their active season corresponds with spring and early summer blooming. Often mistaken for Japanese beetles and rose chafer beetles (they prefer roses, too), hoplia beetles create destruction as adults when they fly from flower to flower to feed.
Hoplia beetles have a dark brown head, an iridescent green body, and brown wings. The beetles are most attracted to light-colored blooms.
Treatment
Hand-picking (or shaking blooms) over a bucket of soapy water is the best course of action for these peony pests. Cut off any blooms with a heavy presence as a streamlined approach. Reducing the insects by picking also minimizes the potential for future populations.
Chemical sprays are viable in catching the immediate offenders, but because hoplia beetles fly and travel, there’s likely a new group ready to take their place. Fortunately, they’re only active for two to four weeks, with mild to moderate damage in their short period of activity.
