Winter Damage

• Damage to boxwoods in late winter or early spring has the potential to inhibit the season's growth of the boxwood shrub. Emerging through the discolored leaves will be wounded young wood, leaf buds and branches. Pruning the boxwood to remove dead or damaged branches helps remove the brown leaves and make the boxwood shrub more attractive. Dead branches contribute to disease and pest problems; removing them keeps the boxwood healthy.
  
  

Leafminers

• Leafminers are pest insects that delve into the leaves of various landscaping plants and shrubs, including the boxwood. The leafminer makes tunnels through the leaves, using them for food and laying eggs. As the leaves get damaged by leafminers, they curl and turn brown. Severe infestations lead to premature leaf drop. Control leafminers with regular applications of pesticides throughout the growing season. Insecticides are targeted to control adult and larval forms of the insect.
  
  

Phytophthora Root Rot

• Phytophthora root rot is a fungal disease affecting boxwood shrubs, according to the Alabama Cooperative Extension Service. As the disease progresses, it causes leaves to turn light green and yellow or brown as they die. Sections of the bush may change color simultaneously, while other portions remain unaffected. Prune severely damaged portions of the boxwood plant and apply a fungicidal treatment to control the presence of the fungus.
  
  

Leaf Spot Diseases

• Leaf spot diseases are caused by a variety of fungi in plants and shrubs. Macrophorma leaf spot affects both English and common boxwood shrubs, causing the leaves to turn brown at the tips and edges and produce dark discolored spots. The spots produce additional fungal spores and spread the disease. Prune affected boxwood plants. Use a fungicide to treat the boxwood and remove any fallen leaves from around the base of the plant, as they can cause repeated infections.