The Pansy Tops Are Rotting

Crown Rot

• Crown rot, caused by the soilborne fungus, Phytophthora parasitica, is a common pansy disease and the likely cause of rotting tops. The leaves turn brownish-green and may have water-soaked spots. Over time, the entire plant succumbs and dies. Remove and discard any infected plants to keep the disease from spreading. Crown rot is most prevalent in warm, moist conditions. Plant pansies when daytime temperatures range between 45 and 65 degrees Fahrenheit. Pansies are usually discarded when hot weather arrives.

Anthracnose

• Anthracnose, caused by the Colletotrichum fungus, causes yellow spots with black margins to form on the leaves. As the disease progresses, the spots turn brown and the leaves die. The flowers may be deformed. Prevent anthracnose by spacing plants so air circulates freely. Using soaker hoses rather than overhead sprinklers can also help by keeping the leaves dry. Remove any infected leaves promptly and destroy severely infected plants. A fungicide treatment, such as one containing mancozeb, can be applied every seven to 10 days throughout the season. Dilute the solution at a rate of 3 teaspoons per 1 gallon of water and place it in a sprayer. Spray to coat each leaf thoroughly. Check the directions on the label because rates vary by brand.

Botrytis Blight

• The Botrytis fungus causes gray mold or botrytis blight, which is characterized by a green or gray fuzzy growth on the leaves and flowers. Later, the infection spreads to cause slimy growth followed by plant death. Botrytis blight can also be controlled by applications of a mancozeb fungicide. Prevention is usually preferable, though. Plant pansies so air circulates freely and water drains quickly. Avoid planting them in areas where disease has occurred previously.

General Guidelines

• Pansies need slightly moist, but well-draining soil. All fungal diseases thrive in heavy, soggy soils. Use a lightweight, sterile potting mix in pots and sterilize old pots before planting by washing them in a solution of 1 part chlorine bleach to 10 parts water. Amend garden soils with compost or peat moss to improve drainage or grow pansies in raised beds. When buying pansies, choose plants that have dark green, compact growth. These plants are the most healthy and are more likely to remain free of diseases. Tall, leggy plants are usually stressed and are more disease-prone. Pansies are short-lived evergreen perennials that might grow year-round in U.S. Department of Agriculture plant hardiness zones 6 through 10. Generally, pansies perform poorly during summer heat and are treated as annuals, either for spring or winter, depending on your climate.