Buxus Problems

Buxus, commonly known as boxwood, is an evergreen shrub that grows between 15 and 20 feet tall. The shrubs are widely used as hedges in formal gardens and as topiaries. Boxwood shrubs are susceptible to a number of diseases and insect problems.

Types

• Phytophthora parasitica and Phytophthora cinnamoni fungi cause phytophthora root and crown rot in boxwood plants. Macrophoma candollei fungus causes macrophoma leaf spot, while the Volutella buxi fungus causes volutella stem blight. Parasitic nematodes feed on boxwood roots. Monarthropalpus buxi or boxwood leafminers feed inside the leaves.

Effects

• Phytophthora root and crown rot is a primarily a problem in damp soil, according to the Virginia Cooperative Extension. The disease is characterized by soggy, rotten roots. Sections of the foliage turn yellow or brown, and infected plants usually die. Boxwoods with macrophoma leaf spot have dark specks of fungal growth on dead leaves. Volutella stem blight causes dieback in twigs. Nematodes stunt the root systems and inhibit plant growth, while boxwood leafminers create swellings on boxwood leaves. Serious infestations cause defoliation and plant death.

Prevention/Solution

• Adequate drainage for plants prevents root rot. Chemical controls prevent infections. Macrophoma leaf spot appears only in stressed plants; the source of the plant stress must be addressed to treat the infection. No chemical controls are available for volutella stem blight. Infected branches must be cut out and destroyed. Soil sprays or biological controls may be helpful against nematode infections. Only those leafminer infections that threaten the plant's health should be targeted with chemical controls, according to Clemson Cooperative Extension.