For area Boxwood shrubs, some good and bad news

Contributed Report

In the last couple of weeks, the Goochland Extension Office has had numerous clients come in with boxwood samples. The good news is that the dreaded boxwood blight (Calonectria pseudonaviculata) has not yet been identified on any sample. Boxwood blight stays dormant while temperatures are below 64 degrees and humidity is low. The bad news is that boxwoods across the county seem to be very stressed.

The source of this stress could be environmental–we had long stretches of dry weather last year, and many landscape plants may not have been irrigated.

This winter has also been all over the place, between the Christmas cold snap and a balmy February. Often, improper cultural practices come into play as well. Shrubs may be planted in the wrong place, mulched too deeply or pruned improperly. Poor pruning can increase the relative hu- midity on the interior of the plant, making it a hospitable place for fungi.

Thus far, the office has seen a fair bit of macrophoma (Macrophoma candollei) and volutella blight (Volutella buxi) on boxwood. These are opportunistic fungal pathogens that take advantage of stressed plants. Volutella appears as a salmon-colored, fuzzy growth on the underside of leaves. Macrophoma looks like ground black pepper. As a general rule, plants with macrophoma and volutella will retain their leaves, whereas plants with boxwood blight will defoliate. Unfortunately, there isn’t an easy fix for these fungal diseases. Most fungicides work best as preventatives and have little ability to cure a disease. Sanitation and reducing plant stress are the best ways to fight these pathogens. Using proper pruning technique, remove the most affected branches. Clean your tools as you move between plants.