Problems With Boxwood Hedges

Boxwood (Buxus) plants come in a diverse range of sizes, forms and textures and are among the most popular plants used for creating hedges, edging plants, borders and natural screens. Shallow-rooted boxwoods grow well in areas of full sun but prefer partial shade. Boxwood plants are susceptible to a number of problems including cultural stresses, fungal disease and insect infestations.

Boxwood plants often suffer from winter damage characterized with reddish brown, yellowish, gray-green foliage color. Often the leaves lose color entirely and there is branch dieback, especially in the middle areas of the crown. Winter injury is also evident with the appearance of sunken areas on the trunk just above the soil line. Poorly growing plants are most susceptible to winter injury. Often plants do not get a chance to harden well before the advent of winter due to untimely rains which can lead to winter injury. Prevention includes spraying boxwoods with an anti-desiccant spray during late November in areas with severe winters.

Boxwoods are susceptible to infestation from boxwood leafminer, 2 1/2mm long flies resembling mosquitoes. The larvae of the flies are 3mm long, light yellow maggots. Boxwood leafminers spend the summer and winter in yellow, blotch-like blisters on the foliage and start emerging as flies during spring. The less vigorously growing boxwoods are more susceptible to damage from boxwood leafminers. Infested leaves take on a water-soaked look. The larvae damage foliage with their feeding. Control includes the use of contact sprays and herbicides at the time of larvae hatching and before damage becomes more severe.

Phytophthora root rot is a fungal disease of boxwoods caused by the soil-borne fungus Phytophthora parasitica. Early symptoms of the disease include loss of vibrant foliage color. Infected boxwood growing in the sun assume a light straw color while plants in shade change to a dull green color. Phytophthora root rot symptoms start from a single branch or section of plant and rapidly spread through the entire plant. The disease is most common in plants growing in poorly drained sites. The best control option includes improving soil drainage and making sure plants are growing well. The use of chemicals for phytophthora root rot has limited effectiveness.