Plant Health Problems
Diseases caused by Fungi:
Cercospora leaf spot, Cercospora spp.
Cercospora leaf spot generally is not a serious disease of leucothoe. However, in years with a cool, rainy spring, Cercospora leaf spot can be a disfiguring disease problem. Leaf spots are usually red in color, and start small, but they may enlarge and coalesce to cover large areas of the leaf surface. In severe instances, foliage may drop from the plant.
Control can be achieved by raking and removing fallen leaves in autumn to reduce the overwintering inoculum capable of infecting new growth in spring. Chemical control is usually not necessary. However, fungicide sprays can be applied when new growth appears in spring. Several applications may be necessary during periods of extended wet weather. Among the compounds registered for use in Connecticut are chlorothalonil, mancozeb, and thiophanate-methyl. Consult the label for dosage rates and safety precautions.
Andromeda lace bug, Stephanitis takeyai.
This lace bug feeds on the Japanese Andromeda, Pieris japonica, and occasionally on Azalea kaempheri but rarely if ever on other broadleaf evergreens, including P. floribunda. Both adults and nymphs suck the sap from the undersides of the leaves, causing a mottling or blanching. The adult lace bug is about 1/8" long. The head covering and markings on the sculptured wings are intensely black. Eggs overwinter in the undersides of the lower leaves. There are three or four generations each year. Among the compounds registered for control of this pest in Connecticut are malathion, insecticidal soap or imidacloprid. When needed, malathion or insecticidal soap can be applied where nymphs are feeding during the last week in May, just after eggs have hatched. Imidacloprid, applied as a soil drench, gives systemic, season-long control of this insect. Consult the label for dosage rates and safety precautions.