The Graham Blandy boxwood (Buxus sempervirens ‘Graham Blandy’) is a popular evergreen shrub, prized for its distinct upright, narrow, and columnar form. Its dense, dark green foliage makes it a favored choice for formal gardens, hedges, and as a vertical accent in various landscape designs. While this plant is generally considered low-maintenance and hardy, it can still encounter a range of problems that affect its health and appearance. Understanding these common issues is the first step toward maintaining a thriving Graham Blandy boxwood in your landscape.
Common Pest Problems
Graham Blandy boxwoods are susceptible to insect pests.
One such pest is the boxwood leafminer (Monarthropalpus flavus), which lays eggs inside leaves. Larvae tunnel within leaf tissue, creating blisters or pockets, and infested leaves may turn yellow or brown before dropping. Control involves systemic insecticides or pruning affected foliage.
Boxwood mites (Eurytetranychus buxi) feed on sap, causing a stippled appearance on leaves that can bronze or discolor. Severe infestations may lead to premature leaf drop. Management involves pruning affected parts or applying miticides, insecticidal soaps, or horticultural oils.
Boxwood psyllids (Cacopsylla buxi) cause new leaves to cup or curl, often with waxy secretions. They feed on new growth, leading to distorted foliage. Pruning infested new growth helps manage populations, and insecticidal soaps or neem oil are effective treatments. Regular inspection is crucial for effective pest management.
Common Disease Problems
Several diseases can affect Graham Blandy boxwoods.
Boxwood blight (Calonectria pseudonaviculata) is a severe fungal disease with dark spots on leaves, black streaking on stems, and rapid defoliation. It spreads quickly in humid conditions and survives in plant debris. Management involves prompt removal of infected plants and debris, fungicides, and strict sanitation.
Volutella blight (Volutella buxi) presents as dull bronze foliage and branch dieback, often with pinkish spore masses on leaf undersides. It is more prevalent in stressed plants; improving air circulation and pruning affected areas are important. Fungicides can also control its progression.
Macrophoma leaf spot (Macrophoma candollei) causes small, straw-colored spots on leaves, often with tiny black dots (pycnidia) in the center. While generally less severe, pruning affected leaves can help reduce its spread.
Root rot, often caused by various fungi, results from overly wet soil conditions, leading to yellowing leaves, wilting, and stunted growth. Improving soil drainage and avoiding overwatering are primary interventions, and in some cases, fungicides may be necessary.
Environmental and Cultural Issues
Environmental conditions and care practices contribute to boxwood problems.
Winter burn, or desiccation, appears as bronzing or browning foliage, especially on exposed sides. It occurs when leaves lose water but frozen soil prevents absorption. Protection involves anti-desiccant sprays, burlap, and thorough pre-winter watering.
Drought stress causes wilting and dull foliage, though established plants are moderately drought tolerant. Deep, infrequent watering is necessary during dry spells. Conversely, excessive watering or poor drainage can lead to yellowing leaves and root rot symptoms, depriving roots of oxygen. Improving soil drainage with organic matter and avoiding waterlogged conditions are essential.
Incorrect pruning impacts plant health and form. Pruning late in the season can encourage tender new growth susceptible to winter damage. Optimal pruning for shaping and removing dead wood is in late winter or early spring.
Nutrient deficiencies, often nitrogen, result in general yellowing, particularly of older leaves. A soil test guides proper fertilization.
Preventative Measures for a Healthy Graham Blandy
Maintaining Graham Blandy boxwood health depends on proactive care.
Selecting a site with proper light and well-draining soil is foundational. They thrive in full sun to partial shade and prefer moist, well-drained conditions. Proper planting, including correct depth and soil preparation, ensures a strong start.
Consistent watering is vital; water deeply and infrequently, allowing soil to dry slightly, and avoid overhead irrigation to minimize disease risk. Fertilize with a balanced, slow-release product in early spring, guided by a soil test. Good air circulation helps deter fungal diseases.
Regular inspection allows timely intervention for pests or diseases. Sanitation, like removing fallen leaves and debris, reduces pathogen reservoirs. Correct pruning, including thinning for airflow and removing dead branches, contributes to plant vigor and disease prevention.