➾ RE S E ARCH FOR THE R EAL WO R L D
cultural practices, biocontrol agents, soil sterilants, and soil surface flaming have been and continue to be investigated as potential control measures with some success. • Whether regulatory actions designed to control the spread of boxwood blight will be implemented by the United States Department of Agriculture — Animal and Plant Health Inspection Service (USDA-APHIS) or by individual states remains unclear; Pennsylvania has, however, become the first state to enact a boxwood blight quarantine (June 25, 2016; http://www.pabulletin.com/secure/data/vol46/46-26/1071. html) and Tennessee is scheduled to become the second state to implement a quarantine on February 4, 2018 (http:// publications.tnsosfiles.com/rules_filings/11-05-17.pdf); these regulations allow the quarantine of any property where boxwood blight is confirmed, restrict the inter- and intrastate movement of any material that my carry or spread the fungus, requires inspection of regulated articles entering Pennsylvania or Tennessee from another state, and requires compliance agreements with growers for production and handling; several other states have implemented voluntary boxwood blight cleanliness programs based on industry-sponsored best management practices and compliance agreements (see below). • Good sanitation and avoiding inadvertent introductions remain best defense; sanitation practices and other actions that can be used to reduce the spread of boxwood blight in nurseries, garden centers, and display gardens and other landscapes include: • Only sourcing boxwood plants, liners, cuttings, and holiday greenery from growers you know and trust and especially growers that are enrolled in state-sponsored boxwood cleanliness/compliance programs. • Inspecting plants for boxwood blight symptoms prior to purchase remembering that asymptomatic plants and plantderived materials can harbor the disease and be a source of infection. • Growing the most resistant boxwood varieties and growing them in full sunlight, with good air circulation, and without overhead irrigation. • Isolating new plant material for at least four weeks away from other plants and shipping areas to allow time for disease symptoms to develop and inspecting these plants weekly. • Avoiding large blocks of boxwood to reduce the potential for significant losses to boxwood blight if it is introduced. • Inspecting boxwood plants and other susceptible species on a weekly basis (scouting), and especially during warm, wet weather. • Wearing clean, disposable shoe/boot coverings (bag and destroy) or carefully removing all debris and soil from footwear between boxwood fields or landscapes and especially locations where boxwood blight is suspected or known to be present. 38
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• Wearing clean, disposable Tyveks coveralls (bag and destroy) or laundering clothes between different field and landscape locations and especially those where boxwood blight is suspected or known to be present. • Disinfecting pruning tools and other equipment frequently and between groups of plants or individual plants in landscape plantings. • Regularly removing and destroying fallen leaves and other plant debris; flaming can be useful in eliminating infected plant debris and in sterilizing surface soils. • Not reusing contaminated growing media or containers or sterilizing used containers; ideally, contaminated media should also be sterilized. • Reporting plants suspected of being infected with boxwood blight and having them tested for confirmation. • After testing, destroying diseased plants by burial or burning (if allowed) on site, double-bagging and sending to landfill, and not composting to avoid spread of the pathogen locally and to new areas. • Following the latest developments in boxwood blight prevention and management and incorporating them into production and landscape maintenance programs. • The boxwood blight pathogen is not going away and will likely continue to spread; breeding for resistance is needed and being pursued; the National Arboretum has a significant boxwood collection and continues to obtain new germplasm from native boxwood populations with the hope that this extensive collection (and others) may be an important resource for breeding and selection activities focused on boxwood blight resistance. Shortly after the disease was confirmed in North America in 2011, AmericanHort (formerly ANLA) created a Boxwood Blight Working Group (BBWG) and, together with the Horticultural Research Institute (HRI; the research affiliate of AmericanHort) and the National Plant Board (NPB), developed research-based guidelines for a Boxwood Cleanliness Program based on a set of voluntary best management practices (BMPs) and a compliance agreement that relies on a systematic approach to clean plant sourcing, early detection, and managing and preventing the spread of boxwood blight. These resources were released in 2012. Since the release of this BMP document, ongoing research focused on species and cultivar resistance, fungicide efficacy, biological control, disease mapping and forecasting, vectors for short- and long-distance spread, pathogen survival, mulch impacts, temperature impacts, and heat treatment (cuttings) and an updated set of BMPs (Version 2.0) was developed and released in September, 2017. The updated version is available through the AmericanHort – Knowledge Center website at https://hortknowledgecenter.org/getattachment/ 7068c31f-fee0-4541-bf4a-ac89350be97b/BoxwoodBlightBMPs2017. pdf?lang=en-US and the “Boxwood Blight Compliance Agreement Template” is available at http://sanc.nationalplantboard.org/state-tools/.