Pansy Diseases & Insect Pests

Pansy Diseases & Insect Pests

Pansies, loved for their vibrant colors, are a popular choice among gardeners. While these flowers are generally trouble-free, there are a few problems that can affect their health and beauty. In this article, we will explore some common diseases and insect pests that may impact your pansy plants, and provide effective prevention and treatment strategies.


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Anthracnose is a fungal disease caused by Colletotrichum species. It leads to browning and blotching of the leaves, with pale yellow spots that have distinct black margins. As the disease progresses, the spots become dry and tan with a concentric ring pattern. Infected flower petals may develop spots and abnormal growth. Severe cases can even result in plant death.

Prevention & Treatment: To combat anthracnose, dig up and destroy severely infected plants. Additionally, promptly remove infected leaves as soon as they appear. Avoid overhead watering, as it can promote disease development. Applying a thin layer of mulch around plants will also help prevent fungal spores from splashing onto the leaves. In cases of serious infection, you can use fungicide sprays containing chlorothalonil or mancozeb at 7- to 14-day intervals until conditions no longer favor disease development. Make sure to read and follow all label instructions and precautions.

Other Leaf Spots

Pansies are susceptible to various fungi, such as Alternaria species, Cercospora species, Myrothecium species, and Ramularia species, which can cause unsightly spots on the foliage. These spots may be transparent tan, brown, or black and can merge to form larger patches of dead tissue. Leaf spots thrive in moist conditions, so it’s important to remove and destroy infected leaves promptly and avoid overhead irrigation. Adding a layer of mulch can help prevent the fungi from splashing onto plants from the soil.

For fall landscape beds, Cercospora leaf spot is a common occurrence, characterized by dry brown blotches or irregular purple lesions, especially in cool weather. To address serious infections, fungicide sprays containing thiophanate-methyl can be used at 7- to 14-day intervals. Follow all label instructions and precautions.

Black Root Rot

Black root rot is caused by the fungal organism Thielaviopsis basicola, which can affect a wide range of ornamental plants. Infected pansies display yellowing, small crinkled leaves, and black discoloration moving up from the tips of the roots. Professional help may be necessary for accurate diagnosis.

Prevention & Treatment: Remove and discard infected plants. Ensure good drainage to avoid overwatering. While the disease cannot be cured, regular applications of fungicides containing thiophanate-methyl can help suppress it. Read and follow all label instructions and precautions.

Root & Crown Rot

Many fungi in the soil, such as Phytophthora species, Pythium species, Rhizoctonia species, and Fusarium species, can infect the roots or base of the plant (crown) at the soil line. Infected pansies may wilt and die suddenly, or their leaves may turn yellow. Dark sunken areas may be visible on the stem near the soil line, and the roots may appear rotted. Some plants may survive but remain weak and stunted.

Prevention & Treatment: These fungi thrive in poorly drained areas with warm soil. Choose locations with good drainage for planting, and consider using raised beds to improve drainage. Avoid excessive watering, allowing the soil to dry between each watering. Proper spacing and moderate mulching around plants will also promote soil drying. To prevent future infections, always remove and destroy diseased plants. Fungicides can be effective on a preventative basis, but repeat applications are necessary. Fungicides containing potassium salts of phosphorous acid can be applied as a drench in the home landscape, suppressing infected plants. Follow all label instructions and precautions.

Gray Mold (Botrytis Blight)

Gray mold, caused by the fungus Botrytis species, appears as a fuzzy, gray coating on the flowers and stems of various plants, including pansies. Infected areas become soft, slimy, and decayed.

Prevention & Treatment: Reduce disease development by keeping plant surfaces dry, removing aging flower blossoms, and providing good air circulation. Avoid overcrowding plants. For serious infections, use fungicide sprays containing chlorothalonil, mancozeb, or copper fungicides at 7- to 14-day intervals. Read and follow all label instructions and precautions. For more information about gray mold and control, please see HGIC 2100 Gray Mold (Botrytis Blight).

Insects & Other Pests


Aphids are soft-bodied insects, ranging in color from tan to black, that feed by sucking plant sap. They leave behind honeydew, a sugary waste material that promotes the growth of a sooty mold fungus on pansy foliage.

Control: Encourage natural predators like ladybird beetles (ladybugs) and lacewings, which feed on aphids. Planting small-flowered nectar plants like Queen Anne’s lace can attract beneficial predators. In cases where natural predators are insufficient, insecticides such as insecticidal soap, cyfluthrin, permethrin, bifenthrin, lambda cyhalothrin, malathion, or acephate can be used. Read and follow all label instructions and precautions.

Spider Mites

Spider mites are not insects but are closely related to spiders. They feed on pansy plants by puncturing plant tissue and sucking sap, causing pinprick holes in leaves. Infestations are more likely to occur during hot, dry periods.

Prevention & Control: Grow pansies during cool spring or fall weather to minimize mite infestations. When infestations occur, use insecticidal soap or other miticides like tau fluvalinate or bifenthrin. Read and follow all label instructions and precautions.

Slugs & Snails

Slugs and snails are nocturnal pests that feed on pansy leaves and blooms, leaving irregular holes. They leave behind a slimy trail of mucus and hide under moist conditions during the day.

Control: Remove mulch and leaf litter near plants to discourage slugs and snails. Handpick them during late evenings using a flashlight. Traps can be made using shallow containers filled with beer or by placing a board on the ground as a hiding place. Sprinkling diatomaceous earth around plants can also protect them. Metaldehyde bait and newer iron phosphate options are available for control. Read and follow all label instructions and precautions.

Other Issues

Pansies may also experience short blooming periods, spindly growth due to low light levels, warty growths on stems caused by overwatering, and nutrient deficiencies. To address these issues, ensure that the plants are grown in cool conditions with adequate light, avoid overwatering, and monitor soil pH levels. Nutrient deficiencies can be corrected by using appropriate soil amendments or foliar sprays.

For more detailed information on controlling diseases and pests specific to pansies, consult the tables provided in the original article.

Remember, maintaining the health and vitality of your pansy plants requires regular monitoring for signs of disease and pests. By promptly addressing any issues that arise, you can ensure that your pansies thrive and continue to bring joy to your garden.

For more gardening tips and resources, visit Tips Tree Planting.

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