Chrysanthemums (mums) bring vibrant color to the garden, but their foliage and flowers are appealing food sources for various animals. Identifying the specific culprit is the most accurate way to address the damage and implement an effective treatment plan. Feeding signs offer clear evidence pointing toward the responsible animal.
Insect Pests Targeting Mums
Minute invertebrate pests cause significant damage by chewing tissue or sucking out internal fluids.
Aphids are small, soft-bodied insects that use piercing mouthparts to extract sap from new growth and leaf undersides. This feeding results in distorted growth, stunting, and the excretion of honeydew.
Spider mites are arachnids difficult to see without magnification. They use piercing mouthparts to remove cell contents, causing fine stippling or tiny yellow spots on the leaves. These pests often leave a fine, silky webbing over affected parts of the plant.
Insects with chewing mouthparts remove larger pieces of foliage. Caterpillars consume tissue directly, resulting in large, irregular holes or skeletonized leaves. Thrips have rasping mouthparts that scrape plant cell surfaces, leading to a silvery or streaked appearance on the leaves and flowers.
Mammals and Mollusks Responsible for Larger Damage
Larger animals and mollusks cause noticeable damage by quickly removing substantial amounts of foliage and stems.
Slugs and snails are soft-bodied mollusks that favor moist, humid conditions near the soil line and feed primarily at night. Their feeding creates irregular, often large holes in the leaves and flowers, giving the plant a tattered look.
Rabbits are ground-level foragers that consume young stems and lower foliage. They possess sharp incisor teeth that leave a clean, angled cut on the stem, similar to a cut made with shears. This damage rarely exceeds 1 to 2 feet in height.
Deer also browse on mums. Unlike rabbits, deer lack lower incisors and must tear or pull the plant material to feed. This results in a ragged, uneven break or tear at the end of the stem or leaf. Deer damage is typically found above two feet from the ground.
How to Identify the Specific Culprit
Examining the damage site closely reveals specific clues about the pest’s feeding mechanism.
Winding, pale trails etched between the upper and lower surfaces of the leaves indicate damage caused by leaf miner larvae. The presence of sticky honeydew, sometimes accompanied by a dark, sooty mold, is a strong indicator of sap-sucking pests like aphids or whiteflies.
When large portions of the plant are missing, inspect the cuts on the remaining stems. A clean, 45-degree angle cut suggests a rabbit, while a stem that looks torn or frayed at the end is characteristic of deer browsing.
Physical Evidence
Specific physical evidence confirms the presence of certain pests:
- Silvery, dried mucus trails left on the leaves, stems, or ground confirm slugs and snails.
- Fine, silky strands of webbing stretched between leaves or stems, particularly on the underside of the foliage, indicate spider mites.
- Small, dark pellets found near the base of the plant confirm the presence of mammals like rabbits.
Protecting Your Mums
Effective protection begins once the specific pest is identified.
For small, soft-bodied pests like aphids and spider mites, a targeted spray of horticultural oil or insecticidal soap can be applied directly to the affected areas, ensuring coverage of the leaf undersides. This treatment smothers the pests and disrupts their life cycle.
Larger chewing insects, such as caterpillars, can often be managed by hand-picking them. Slugs and snails are controlled by removing their daytime hiding spots (mulch and debris) and using non-toxic bait or copper barriers placed around the plant base.
Preventing damage from mammals like deer and rabbits requires physical exclusion or repellents. Installing a fence or cage barrier prevents larger animals from reaching the foliage. Motion-activated water sprinklers or commercial repellents can also be used as deterrents.