Stopping the Spread of Blight with Science & Strategy

Corrina Murray

With its capacity to quickly transform boxwood bushes from green and thriving to brown and blighted in rapid time, Cylindrocladium buxicola (also known as Calonectria pseudonaviculata)—the cause of boxwood blight—appropriately alarms wholesale growers and home gardeners alike.

Symptoms of blight often first appear as light or dark brown leaf spots and black stem cankers; defoliation may follow rapidly. Pathogen spores are easily spread by rain, irrigation water, and even contaminated tools and equipment.

Pictured: More than 50 historic gardens have been replanted with Better Boxwood varieties, including the Palace of Versailles, which was renovated for the 2024 Olympics in Paris.

Boxwoods are hugely popular landscape plants, beloved by horticulture industry members and homeowners for different, but connected, reasons: Boxwood’s huge economic value to the nursery industry is driven by the plant’s foundational role in home landscapes. The numbers tell the story well—according to the 2019 Hort Specialties Census, about 28 million boxwood plants were in production in 2019, with more than 12 million boxwood plants sold for total sales of $141 million.

In 2011, boxwood blight was detected in Connecticut and North Carolina. Since this first U.S. detection, boxwood blight has been reported in more than 20 states and three Canadian provinces. But long before U.S. growers became familiar with the potential devastation of boxwood blight, Flemish breeder Didier Hermans was scouring the boxwood genome for blight-resistant boxwood varieties.

Boxwood blight, first found in the United Kingdom in 1994, had spread throughout the country in just six years and was subsequently found in continental Europe. Plant breeders like Didier knew finding a solution was crucial.

Didier’s company Herplant BV accumulated more than 200 buxus species and cultivars from around the world, including wild European buxus populations. Their research mapped out the best characteristics, including hardiness, leaf color, leaf shape, winter color, and of course, resistance to disease. Beginning in 2007, with the best selections Herplant produced 10,000 seedlings, inoculating those with fungal spores and then subjecting the survivors to strenuous field testing.

The 20-year process eventually resulted in four blight-resistant varieties and this spring, Plant Development Services—in partnership with Everde Growers—introduced them in North America in select retail stores (the launch will expand nationwide in 2025).

Introduced as Better Buxus in Europe and Better Boxwood in North America, the new boxwood varieties are the first collection of boxwood scientifically bred for their ability to resist boxwood blight.

Because of the outsized impact of blight on Europe’s historic landscapes, the Better Boxwood team sought the endorsement of these trusted landscape managers as they released the new varieties. More than 50 historic gardens have been replanted with the Better Boxwood varieties, including one very well-known example: the Palace of Versailles.

When the garden managers of the venerable Palace of Versailles decided to renovate the Palace’s boxwood parterre gardens this summer in preparation for the Paris 2024 Olympics, they chose the newest and most exciting boxwood introductions to hit the market in decades.

Cream of the crop

The lengthy breeding, trialing and selection process that the Better Boxwood varieties underwent had another benefit, said Kip McConnell, Director of Business Development for Plant Development Services, Inc.

“We were thrilled to see that these new varieties excelled in characteristics beyond disease resistance. They are vigorous plants that stay green longer during cool seasons, and demonstrate cold and heat hardiness. Not only were they bred for blight resistance, but they are also better boxwood,” Kip said.

More than 50 wholesale growers across the United States are now part of the licensed grower network for Better Boxwood, but Kip invites interested growers to join the team.

“We have the chance to deter boxwood blight wherever it might spread, with monitoring, detection, and with the growing and planting of these resistant varieties,” Kip said.

Along with reducing disease potential, growers can expect increased profits, said Kevin Northrop, Vice President of Marketing & Operations, Plant Development Services, Inc.  

“Plant Development Services and our partner Everde were selected to introduce Better Boxwood in the United States, in part due to our long track record of introducing game-changing plant brands and supporting their path to retail in a way that makes money for growers and retailers,” said Kevin. “This is the perfect example of our process to increase grower profits. We’ve introduced an improvement on a beloved traditional plant type, and we’re backing that introduction with impactful consumer marketing, with an emphasis on flexible grower partnerships that support wholesale growers.” GT 

Corrina Murray is the Director of Marketing for Plant Development Services, Inc.