Troup extension agent: Boxwood blight moves into Troup County

Published 12:00 am Friday, February 5, 2016

By Brian Maddy

Contributing columnist

We have a confirmed report of the boxwood blight in Troup County.

It has killed both English and American boxwoods in Hogansville. The plants infected were mature, established plants with no record of new plants being brought to the site.

Once infected, the plants die. There is no post treatment at this time.

Boxwood blight was introduced in the United States in the fall of 2011. It has spread to multiple states and Canada. It has been in the United Kingdom and Europe for over a decade.

Georgia reported it first cases in 2014. There are no commercial boxwood cultivars that are immune to the disease. There are more resistant varieties or more tolerant varieties that may act as a “Trojan horse.” These exhibit no symptoms but are carriers and may introduce the disease into an established landscape.

The blight affects other plants in the buxaceae family including pachysandra terminalis and sarcococcca species, which are also known as sweet box.

Symptoms of boxwood blight include circular, tan leaf spots with a dark purple or brown border and black stem lesions or blackening of the stems. The infected leaves turn tan and readily drop leaving bare stems. Sections of the plant or the whole plant turns tan and dies.

Volutella blight is similar except the leaves stay on board. Phytophthora root disease and root disease also mimic the symptoms.

The black stem lesions are the key clue. Wet, humid, shady, warm conditions are perfect for spreading this pathogen.

Leaves remaining wet for 24 to 48 hours is required for the disease. Dry conditions prevent the spread.

How does boxwood blight spread? The spores are extremely sticky and can stick to shoes, clothes, tools, animals, leaves and debris. The spores are not windborne, but leaves that are infected can blow off of trucks and spread the infection.

Spores can stick to the fur and feathers of both domestic and wild animals. Pruning tools are also a big culprit. Shoes and clothing are also culprits.

The best prevention is exclusion. Do not spread the disease by introducing infected plants and tools to your boxwoods.

Inspect all new boxwoods for symptoms and only buy from nurseries that have a boxwood blight compliance agreement. Quarantine new plants for at least a month and do not apply any fungicides to them.

Never install or prune boxwoods when wet. Do not use overhead watering.

Make sure your landscapers or lawn care specialists are sanitizing their equipment from site to site. A 10 percent bleach solution, one part Clorox and nine parts water, works well.

Soak for at least 10 seconds and allow to dry. The best product is Lysol concentrate disinfectant. Mix 2.5 tablespoons per gallon of water. Keep in spray bottles and wet the tools for at least 10 seconds and allow to dry.

Sanitize your shoes and boots, and wash your clothing between working with uninfected boxwoods and infected ones.

Fungicides can be applied preventatively. It will not cure plants infected with boxwood blight.

Fungicides are only effective when applied preventively. Chlorothalonil containing fungicidessuch as daconil, spectro and concert II and those containing fludioxonil, medallion and palladium, provided the best control when applied preventatively.

If you suspect that your boxwoods are infected, call the extension office and we will send a sample to UGA for confirmation. If confirmed, all the infected plants and fallen leaf debris need to be bagged on site and removed to be buried in a landfill to prevent spreading.

All bags should be closed securely. Fallen leaf debris should be vacuumed and bagged or burned on site. It should not be composted. The fungus can live for years in dead plant debris.

An option is to remove the plant soil and replace with new, but this still doesn’t guarantee that the soil will be blight free.

Both English boxwoods and American boxwoods provide much beauty to our landscapes in Troup County. It’s unfortunate that the boxwood blight has moved to Troup County. Inspecting your plants, adjusting your watering methods and applying preventive measures can help aid in the preventing the spread of boxwood blight.

What’s going on in Extension?

Feb. 10: Small farm and agriculture workshop: Localizing the Business of Food, 8 a.m. to 5 p.m.; Callaway Conference Center, 220 Fort Drive. Call 706-881-1249 for more information.

Feb. 11: MGEV meeting, Ag Center, 7 p.m. Guest speaker: Tia Gonzales, Auburn University.

Feb. 15: Troup County Association of Beekeepers, 7 p.m., Ag Center.

Feb. 16: Troup County Cattleman, 7 p.m., Ag Center, dinner starts at 7 p.m. Cost is $6. Program at 7:30 p.m. Guest speakers: 4-H and FFA officers.

Feb. 18: Timber growers meeting, Ag Center, 7 p.m. Guest speaker: Joseph Moore. Topic: Reforestation.

Tree seedlings can be ordered from the Georgia Forestry Commission, 706-845-4122.

Brian Maddy is the ANR Agent for Troup County Extension. The Troup County Extension office is located at 114 Church St. in LaGrange and may be reached at 706-883-1675, Monday–Friday 8 a.m.–noon and 15 p.m.