Tag Archives: boxwood blight

Update on the Boxwood Blight Situation in Virginia and Recommendations for Minimizing Disease Introduction and Spread from the Virginia Boxwood Blight Task Force

Current situation in Virginia, 10/6/17

According to records of the Virginia Boxwood Blight Task Force, to date boxwood blight has been diagnosed in over 70 locations and approximately 30 counties in Virginia. There are likely additional undocumented incidences of the disease, for example, if no sample was submitted for diagnosis through Virginia Cooperative Extension or the Virginia Department of Agriculture and Consumer Services.

Although boxwood blight has been diagnosed in many counties in Virginia, there is no indication that it is widespread throughout any Virginia county. This is not unexpected, based on the current understanding of the biology of the boxwood blight pathogen. Boxwood blight is typically initially introduced into a new location on infected boxwood or other susceptible plants (e.g. pachysandra and sweet box). Holiday greenery containing infected boxwood can also introduce the disease into a new location. However, boxwood blight is not spread long-distance via wind currents. Therefore, one need not panic even if the disease has been found in one’s county. However, if the disease has been identified in one’s neighborhood, then there is a heightened risk of local spread of the disease.

After the initial introduction of boxwood blight-infected boxwood (or pachysandra or sweet box) into a location, neighborhood boxwood plantings are at risk for boxwood blight. There are a number of means by which the sticky spores of the fungal pathogen can move through a neighborhood. For example, they can be spread via contaminated pruning tools, spray hoses, equipment, vehicles, clothing, shoes, or infested leaves spread by leaf blowers. Wildlife (including birds), insects, domestic animals or humans that have been in contact with the spores may also move the infective spores through a neighborhood. Movement of the pathogen by many of these means has been documented in locations in Virginia.

To safeguard Virginia boxwood plantings and production, we call for community awareness and efforts to avoid accidental introduction of boxwood blight into new locations and prevent local spread of boxwood blight:

Specifically, we recommend and stress the following:

  • Purchase boxwood, pachysandra and sweet box only from a nursery that is listed as a member of the Boxwood Blight Cleanliness Programand/or from a retailer who sells only boxwood produced by nurseries in the Boxwood Blight Cleanliness Program.
  • If boxwood blight is suspected, immediately contact your local Extension office, which can submit a sample for confirmatory diagnosis. Where boxwood blight is confirmed, it is strongly recommended to immediately remove and double bag all diseased plants and fallen leaves as well as contaminated soil underneath the planting. The bagged waste should be removed to a designated landfill to mitigate disease spread to other boxwood in the landscape and other properties nearby.
  • Employ only landscape professionals who are aware of how boxwood blight spreads, since boxwood blight can be introduced to properties through landscape maintenance activities. The fungal spores and fallen diseased leaves can be moved on tools, boots, tarps, hoses, clothing and vehicles. Landscape professionals should have a stringent sanitation plan in place to decontaminate tools, equipment, vehicles, clothing, shoes, etc. between landscape locations and other practices that minimize the chance to move the disease through landscaping activities.
  • Adhere to best management practices outlined for boxwood blight, which are detailed in PDFs available at the Virginia Boxwood Blight Task Force website.

Additional Precautions for Landscape Professionals:

  • Landscape professionals are strongly advised to walk through a site before beginning work. This is to identify any potential boxwood blight problems and/or risks. We have heard anecdotal reports from landscape professionals of both serious equipment contamination issues and spread of the disease by unexpected encounters of the disease in a landscape.
  • Landscape contractors should at all times be equipped with a sanitation “kit” for disinfesting tools and equipment and take precautions to avoid moving spores on clothing, boots, hoses, vehicles, etc. Specific recommendations for effective sanitation methods are detailed on the Virginia Boxwood Blight Task Force website (under the “Sanitizers” tab).
  • Landscape companies should ensure their staff are familiar with the symptoms of boxwood blight so that they can recognize the disease in the landscape. Laminated wallet cards with images of symptoms of boxwood blight and information on the Virginia Boxwood Blight Task Force website are available through your local Virginia Cooperative Extension

Resources: the Virginia Boxwood Blight Task Force website and Best Management Practices

Refer to the Virginia Boxwood Blight Task Force website for further information on boxwood blight. We recommend that you familiarize yourself with the appropriate Best Management Practice (BMP) for your situation. The BMPs are available on the website as PDFs.

Update on Boxwood Blight in Virginia

English boxwood defoliated by the boxwood blight pathogen following introduction of infected container plants on the patio. (Photo by A. Bordas)

English boxwood defoliated by the boxwood blight pathogen following introduction of infected container plants on the patio. (Photo by A. Bordas)

Recent outbreaks of boxwood blight, caused by the fungus Calonectria pseudonaviculata, are causing concern in Virginia. Boxwood blight can cause severe defoliation of susceptible boxwood, including English and American boxwood, and is of serious consequence to nursery growers, landscapers and homeowners. All diagnoses of boxwood blight in home landscapes made by the Virginia Tech Plant Disease Clinic since last fall are linked to new boxwood purchased from several Virginia locations of one national retailer, and new cases are likely to emerge. (See news article at: http://www.newsadvance.com/news/local/boxwood-blight-hits-lynchburg/article_a2860e97-438c-523a-9c63-202902eaf42b.html).

We strongly recommend that growers purchase boxwood from a nursery or retail outlet that has purchased boxwood exclusively from a boxwood producer in the Boxwood Blight Cleanliness Program (http://www.vdacs.virginia.gov/plant-industry-services-boxwood-blight.shtml). These producers follow stringent practices to avoid the introduction of this disease to their nurseries and are subject to followup inspections by the Virginia Department of Agriculture and Consumer Services.

Black streaking on green stems of boxwood plant with boxwood blight.

Black streaking on green stems of boxwood plant with boxwood blight. (Photo by A. Bordas)

Symptoms of boxwood blight include leaf spots, black streaking on stems and severe defoliation. Other diseases of boxwood, such as Volutella blight and root diseases, can be confused with boxwood blight; therefore, laboratory confirmation is necessary. Learn to recognize symptoms of boxwood blight by viewing the image gallery on the Virginia Boxwood Blight Task Force web site (http://www.ext.vt.edu/topics/agriculture/commercial-horticulture/boxwood-blight/). Information on best management practices, resistant boxwood cultivars, and sanitizers for cleaning tools is also available on the web site.

In all the cases of boxwood blight diagnosed by the VT Plant Disease Clinic in home landscapes, the disease was introduced on infected boxwood plants. The fungus has sticky spores and is not adapted for movement on air currents; however, spores may stick to and be transported by spray hoses, tools, clothing, shoes, and vehicles. The fungus can also be transported in soil and likely by animals moving through infected plants, e.g. deer, dogs. Infected boxwood may also be present in holiday greenery.

If you suspect boxwood blight, collect symptomatic branch samples with at least a few green leaves still attached. Double bag the samples in sealable bags and take them to your local Virginia Cooperative Extension office (http://www.ext.vt.edu/offices/index.html). Samples will be forwarded to the Virginia Tech Plant Clinic for diagnosis.