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Problem
(factsheet)
Plant NameTypeDescription 
Box blightBoxwoodDiseaseBox blight is a fungal disease that causes leaf spots, stem cankers or black streaks, and foliar blight, and defoliation. Symptoms of blight and defoliation can appear suddenly and affected plants may lose all their leaves. Blighted leaves may be straw- to bronze-colored. White fungal growth may be observed on the underside of the infected leaves. Box blight can be confused with other problems, including boxwood canker. Boxwood canker often infects plants infected with box blight. High humidity or free moisture are necessary for the fungal infection. Planting boxwoods in hedges and/or severely shearing them can result in more disease. Buxus spp. and cultivars, Pachysandra and Sarcococca are hosts.
CankerBoxwoodDiseaseBoxwood canker is caused by a fungus which often infects branches through pruning wounds or at branch crotches, where infected, dead leaves have accumulated. Leaves of affected branches often change color to light green, yellow, then tan. The leaves of affected twigs turn upward and lie close to the branch. Twigs may die back above the infection site. Fungal fruiting bodies may be present on the affected leaves. They are rose-colored and waxy in appearance. English or common boxwood (Buxus sempervirens) is reported to be susceptible to canker.
Leaf spotBoxwoodDiseaseBoxwood leaf spot is caused by fungi which survive in fallen, diseased leaves beneath the plant. Leaves develop discolored spots and may turn tan or brown from the margins and tips inward. Small, black fruiting bodies of the fungus often appear on the discolored spots or the underside of the leaves. Leaf spot is favored by wet, humid weather and damp planting conditions.
Phytophthora root rotBoxwoodDiseasePhytophthora is a fungal infection of the roots and crown. Infected plants often show wilting, discolored or dead leaves which remain on the branches, dead twigs and branches, stunting, gradual decline, and premature plant death. Infected roots become watersoaked and rot. Streaking or dark staining may be observed when cuts are made into the wood near the crown of the plant, or cankers may be present on the crown. The fungus persists in the soil and in diseased plant material. Phytophthora prefers high soil moisture.
Boxwood leafminerBoxwoodInsectLeafminers feed by removing green tissue from between the upper and lower leaf surfaces. Feeding by leafminers can be detected by the presence of yellow to brownish blotch-like mines or by a blistered, thickened appearance of the leaves. The larval stage of the boxwood leafminer is a small yellow to green maggot found inside the mined leaves. The adult is a small (1/10") orange to yellow fly which emerges in early May. Damage is mainly aesthetic, but repeated severe infestations may damage shrubs.
Boxwood miteBoxwoodInsectBoxwood mites are small and greenish brown. Their presence is typically indicated by small white, yellow, or bronze streaks resembling fine scratches or speckles on the upper surface of leaves. The mites may be found on the upper or lower surface of leaves. Heavy infestations may result in premature leaf drop. Mite infestations are often worse during dry, dusty conditions.
Boxwood psyllidBoxwoodInsectThe presence of the boxwood psyllid is indicated by the cupping of leaves at the tips of terminals. The white immature psyllids (nymphs) feed on the developing buds and leaves at the tips of branches, causing the characteristic cupping and sometimes killing the buds. The greenish, aphid-like adult psyllids are about 1/8" long and jump. Honeydew, a shiny, sticky material produced by the insects, may be present. The honeydew may become covered with a growth of black sooty mold. English boxwood (Buxus sempervirens) is reported to be somewhat less susceptible.