New Safeguards for Boxwood from Canada
USDA-APHIS announced new requirements for Buxus, Euonymus, and Ilex entering the U.S. from Canada in response to box tree moth presence in Ontario.
Effective immediately, these plant species, including propagative material, must be accompanied by a phytosanitary certificate with an additional declaration certifying that the plants have been produced in a facility officially recognized by the Canadian Food Inspection Agency (CFIA) as being free of box tree moth or that the shipment has been officially inspected and found to be free of box tree moth.
Box tree moth (Cydalima perspectalis) was first identified in the Toronto, ON area in August 2018 by a photo enthusiast. This is the first observance of this pest in North America. CFIA later confirmed box tree moth presence and deployed pheromone traps throughout southern Ontario. In 2019, over 300 residences were found with box tree moth in the landscape, most in the Etobicoke area. Over 400 additional ‘suspect finds’ were documented but remain unconfirmed.
APHIS has also made pheromone traps available to state departments of agriculture wishing to monitor for box tree moth in 2020.
The Ontario Ministry of Agriculture, Food, and Rural Affairs currently does not mandate that infested landscapes be treated. The only pesticide treatment available in Ontario for this purpose is Bacillus thuringiensis. While very effective, few homeowners with positives or suspect finds (less than 10%) have chosen to have their landscapes treated; the vast majority remain untreated.
Box tree moth overwinters as larvae that emerge when temperatures warm in the spring. A female lays about 400-800 eggs over her lifetime on leaf undersides; eggs are very difficult to see. The lifecycle from an egg to an adult takes about 45 days. Adult moths can fly an estimated six to twelve miles per generation, with anywhere from two to five generations per year expected in the U.S. However, human-mediated movement is the likeliest way this pest is spread long distances. Host material includes Buxus, live or dead plants and greenery. Asian researchers have implicated Euonymus and Ilex as two other hosts; however, researchers in the EU have not confirmed this.
APHIS recently announced funding of research projects aimed at plant pest and disease management, including a study to evaluate sterile insect technology and mating disruption of box tree moth.
The EU first reported box tree moth in 2007 in Germany. It spread quickly from there – throughout all of the EU within ten years – primarily through the plant trade. Boxwood producers, retailers, and landscape installers and managers need to be vigilant in scouting. If an unusual caterpillar and/or webbing is visible on boxwood, please contact your county extension agent as soon as possible.