This past week I confirmed GA’s first case of Boxwood blight in a residential landscape in the Buckhead area of Atlanta. I then visited a second Buckhead site and it too had boxwood blight.
Boxwood blight is not a federal or state regulated disease. It is however, a very devastating disease for landscapers and boxwood growers. The disease spreads quickly and easily. It is often introduced into nurseries and landscapes on infected plants; however, in one of the infected sites, the disease cannot be traced back to an introduced plant. The landscape was likely infected by workers pruning boxwoods or installing annual flowers within the landscape bed. This means that there are likely other landscapes that are infected that we don’t know about yet. The second landscape consisted of field- and container-grown plants originating from NC that were transplanted within the past two months. Almost all of the plants (100+) showed symptoms to some extent.
Also, last week infected boxwoods originating from Monrovia Nursery in Oregon were found in a retail garden center in Chattanooga, TN. All but 25 plants were recovered from that location. It is likely that some of these plants or other shipments from the same nursery have ended up in GA. As of yet, we have not found boxwood blight in any commercial production nursery in the state.
I wrote a disease alert/fact sheet for the industry on boxwood blight. You can access it here: http://plantpath.caes.uga.edu/extension/extension/documents/GABoxwoodBlightAlertv1.pdf
Be extra cautious about boxwood samples. We have seen a lot of dieback in boxwood across the state from winter injury, Phytophthora root disease, and Volutella blight. Boxwood blight symptoms usually develop rapidly. Leaf spots can develop within days of inoculation progressing to blackening of the stems, foliage death, and leaf drop within two weeks. However, much of the state has been dry and the disease progression within the Atlanta landscapes has been slower. Moisture is the key. If we enter into a period of late afternoon thunderstorms and high humidity, disease progression will be quicker.
There is no control for this disease other than removal of infected plants and strict sanitation to reduce disease spread. Fungicides are only preventative. They are ineffective in controlling the disease once present.