Monarda Pests

Nematodes

• The root lesion nematode is responsible for causing damage to the roots on mint plants, including monarda specimens. The nematode feeds on the small roots, causing them to turn brown. This type of condition occurs most commonly in monarda that grows in soggy soils previously inhabited by onions and potatoes. Fumigating the soil with a product that contains chlorothalanil or myclobutanil can help protect the health of the monarda plant.

Mites

• Mites that feed on monarda plants tend to stunt and distort the upper growth, especially late in the growing season. The mint bud mite is the most common type of mite that attacks mint plants, although the two-spotted spider may also be a culprit. Chemical insecticides that contain propargite or dicofol are suitable for controlling mite infestations. Like most pesticides, these chemicals contain ingredients that may harm beneficial bugs and insects, such as the butterflies and bees that frequently land on monarda plants.

Beetles

• The mint flea beetle is a common pest that feeds on mint plants. The adult beetles feed on the leaves during early to mid-summer. After about three weeks, the adults lay their eggs in the soil near the crown of the plant. As the larvae hatches in the spring, they begin feeding on the nearby roots, then work their way into the stems. Their tunneling causes monarda plants to produce spotted foliage and stunted growth. Malathion or insecticides that contain methomyl can help eliminate these harmful beetles.

Diseases

• Although insects can damage monarda plants, the most prevalent risk to this plant comes from powdery mildew, a type of fungus that creates the appearance of whitish-gray powder over the surface of the monarda leaves. Providing adequate airflow and abundant sunlight, as well as treating the soil with a fungicide drench, can help protect monarda plants.