Impatiens are popular garden plants, cherished for their vibrant blooms in shady spots. While easy to grow, they are susceptible to pests and animals that can cause significant damage. Identifying the specific cause is crucial for effective treatment.
Signs of Damage on Impatiens
Observing impatiens closely can reveal various signs of pest activity. Chewed leaves with irregular holes or ragged edges often point to feeding by larger insects or animals. Tiny yellow or bronze speckles, known as stippling, can appear on leaves, often leading to bronzing or yellowing.
A sticky residue on the leaves and stems, often called honeydew, suggests sap-sucking insects. This residue can also lead to black, sooty mold. Plants might show wilting or stunted growth, even when adequately watered, which can be a symptom of root damage or severe sap loss. Fine webbing, particularly on the undersides of leaves, indicates certain pest infestations. In severe cases, entire flowers or sections of stems may be missing, signaling a visit from larger garden browsers.
Common Pests Attacking Impatiens
Various organisms feed on impatiens, each leaving distinct signs. Understanding these patterns helps in accurate identification.
Slugs and Snails
Slugs and snails are soft-bodied mollusks active at night or on damp days. They leave large, irregular holes in leaves and flowers, often starting from the edges. A clear sign is the distinctive silvery slime trail on foliage and surrounding surfaces.
Aphids
Aphids are small, soft-bodied insects (green, black, pink, or yellow) often found clustered on new growth, stems, and undersides of leaves. They feed by piercing plant tissues and sucking sap, leading to distorted, curled, or yellowed leaves. Aphids excrete honeydew, making plant surfaces sticky and encouraging sooty mold growth.
Spider Mites
Spider mites are tiny arachnids, often red or green, difficult to see without magnification. Their feeding causes small, pale spots or stippling on leaves, progressing to bronzing or yellowing. A definitive sign is the fine, silken webbing they spin, particularly on the undersides of leaves and between stems.
Caterpillars
Caterpillars are the larval stage of moths and butterflies, varying widely in size and color. They chew on plant tissue, resulting in ragged holes in leaves and flowers, and sometimes extensive defoliation. Visible droppings, known as frass, are often found on leaves or at the base of the plant.
Earwigs
Earwigs are reddish-brown insects with distinctive pincers. They are nocturnal feeders that create irregular holes in leaves and flowers, similar to slug damage but without a slime trail.
Japanese Beetles
Japanese beetles are identifiable by their metallic green bodies and coppery-brown wing covers. These voracious feeders consume soft tissue between leaf veins, leaving a skeletonized appearance. They also feed directly on flowers, damaging blooms.
Deer and Rabbits
Deer and rabbits are larger mammalian browsers that can cause significant damage. Deer tear at plants, resulting in ragged edges on stems and leaves, often consuming entire flowers or young shoots. Rabbits make cleaner, sharper cuts, especially on young stems and leaves.
Effective Control Strategies
Once the culprit is identified, several strategies can manage impatiens pest infestations.
Manual removal is a straightforward, non-toxic method for many pests. Slugs and snails can be hand-picked from plants at night and dropped into soapy water. Aphids can be dislodged with a strong stream of water from a hose. Larger pests like caterpillars and Japanese beetles can also be hand-picked.
Horticultural oils and insecticidal soaps effectively treat soft-bodied insects like aphids and spider mites. These products suffocate pests or disrupt their cell membranes. Apply thoroughly, covering both upper and lower leaf surfaces, preferably in cooler temperatures to avoid plant stress.
For larger animal pests, physical barriers and repellents are useful. Fencing, such as chicken wire or mesh buried a few inches into the ground, can deter rabbits. Deer repellents, which taste or smell offensive, can be sprayed on plants.
Cultural practices also support pest management. Proper watering helps plants resist stress, as stressed plants are more vulnerable to pests. Cleaning up garden debris removes hiding places and breeding grounds for slugs, snails, and other pests.
Preventative Measures
Proactive measures can significantly reduce pest infestations. Proper plant spacing allows for good air circulation, which helps foliage dry quickly and discourages fungal issues that can weaken plants and make them more susceptible to pests.
Regularly monitoring plants for early signs of pest activity allows for prompt intervention before infestations become severe. Maintaining overall plant health through appropriate watering and fertilization supports strong growth, making impatiens less attractive to many pests. Cleaning up garden beds regularly, removing fallen leaves and other debris, eliminates potential hiding spots and breeding sites for slugs, snails, and earwigs. Companion planting may deter some browsing animals like deer and rabbits.