Plant Health Problems

See Perennials for a detailed discussion of problems that may occur and are common to most herbaceous ornamentals.

Diseases caused by Fungi:

Anthracnose, Colletotrichum.
Symptoms appear on the infected leaves as light tan to brown spots which can be circular or irregular in shape. The spots often have indefinite purple margins. Small black fruiting bodies may be found in the center of the spots. When infection occurs on seedlings, they topple over from stem infection.

Efforts to maximize plant vigor by fertilizing and watering are helpful. However, watering should be done early in the day to give the foliage a chance to dry before nighttime. It is also helpful to pick and remove symptomatic leaves as soon as they develop. Although not usually necessary, applications of fungicides can be made when new growth emerges in the spring. Among the compounds registered for use in Connecticut is mancozeb. Consult the label for dosage rates and safety precautions.

Leaf spot, Ramularia.
Leaf spots appear first on lower leaves as brown spots with reddish borders. When infection is heavy, entire leaves shrivel and die.

Efforts to maximize plant vigor by fertilizing and watering are helpful. However, watering should be done early in the day to give the foliage a chance to dry before nighttime. It is also helpful to pick and remove symptomatic leaves as soon as they develop. Although not usually necessary, applications of fungicides can be made when new growth emerges in the spring. Among the compounds registered for use in Connecticut are chlorothalonil and thiophanate-methyl. Consult the label for dosage rates and safety precautions.

Insect Problems:

Mealybugs.
Several species of mealybug, including the citrus and ground mealybugs, attack perennials; foxglove and heuchera are particularly susceptible. Mealybugs suck plant sap during all stages of plant growth, causing stunted growth and distorted leaves. White cottony masses appear on leaf surfaces, in leaf axils and sheaths. Among the compounds registered for control of this pest in Connecticut are malathion, insecticidal soap or ultra-fine horticultural oil, which require contact with the insect to give good control. Consult the labels for dosage rates and safety precautions. Ants tend mealybugs to harvest their honeydew, and sometimes move mealybugs to uninfested plants. Ants may also protect sucking insects from their predators and parasites, so ant control should be considered as an important component in managing mealybugs. Imidacloprid applied as a systemic to be taken up by the roots provides season-long control.