The Boxwood Revolution

By Lindsay Day

Boxwood (Buxus sp.) have been gracing landscapes for thousands of years. These slow-growing evergreen shrubs stand as a symbol of a gardener’s commitment and investment to a green space. Boxwood have held their reputation for many years because they are low maintenance, provide structure to a garden, and have few pests and disease pressures. Unfortunately, this reputation took a hard hit in the United States in 2011 with the discovery of Boxwood Blight. Many growers became concerned about the future of this beloved plant.

Saunders Brothers, Inc. in Piney River, VA, a family-run nursery with a long history of boxwood production, responded to this threat by investing in research to find a solution. With over 70 years of experience in boxwood cultivation, they had seen boxwood through setbacks before.

Boxwood Leafminer

In the early 2000s Saunders Brothers, Inc. moved towards larger field-grown boxwood and continued to grow many different varieties and cultivars. Buxus microphylla ‘Green Beauty’, Buxus x ‘Green Velvet’, Buxus sempervirens ‘Justin Brouwer’, and Buxus x ‘Green Mountain’ soon became huge sellers for Saunders Brothers, Inc. as well as other nurseries throughout the United States. With time, however, these four boxwood cultivars were discovered to be highly susceptible to Boxwood Leafminer damage.

Robert, Tom, Paul, Bennett, and Jim Saunders walking through one of their peach orchards.

Bennett Saunders, who oversaw field boxwood production, noticed that the Boxwood Leafminer was cultivar-specific, meaning certain cultivars showed heavy infestations while other cultivars showed minimal, if any, damage by the burrowing larvae.

An adult Boxwood Leafminer on a branch of infested leaves

In 2007, Saunders Brothers, Inc. engaged Dr. Bob Dunn, a retired nematologist from the University of Florida, to collect data on natural resistance of cultivars to the Boxwood Leafminer. Dunn planted replicated research trials in a boxwood growing area that was infested with Boxwood Leafminer. Over a period of ten years, he gathered data from almost 150 cultivars to determine varietal resistance to Boxwood Leafminer.

Dr. Bob Dunn dissected leaves and counted live Boxwood Leafminers over a ten-year period.

In the meantime, Bennett traveled through the eastern United States to Blandy Research Farm near Winchester, VA, the National Arboretum in Washington, D.C., and to many nurseries and private collectors, seeking other cultivars which showed natural resistance to the Leafminer. Some of these varieties were brought back to Saunders Brothers, Inc. for formal testing and to be added to the Saunders Brothers, Inc. collection.

Boxwood Blight

After the introduction of Boxwood Blight into the US in 2011, Saunders Brothers sent a team to Europe to learn as much as they could about the disease. Growers and researchers in Europe remarked that they had seen a difference in susceptibility to the disease based on the genetics of the plants. With Saunders Brothers’ diverse collection of boxwood cultivars, they were excited that some of their cultivars would have resistance.

Symptoms of Boxwood Blight, including leaf spots and dark streaking on the stem

In the spring of 2012, Saunders Brothers began to ship hundreds of cultivars to North Carolina State University. Kelly Ivors, a research scientist in Mills River, North Carolina, began a 3-year study to determine the relative susceptibility of various boxwood cultivars to Boxwood Blight. Ivors’ research found the cultivars that Saunders Brothers, Inc. delivered were highly variable in their susceptibility to the Blight. Some cultivars showed extreme susceptibility and others showed extreme resistance to the disease, with all shades of susceptibility in-between.

The team of researchers at NC State

Several years later Kelly Ivors moved to the West Coast, but Saunders Brothers, Inc. continued to research Boxwood Blight. Bennett found a site about 150 miles away from the Saunders Brothers, Inc. that had already been infected with Boxwood Blight where they began to do “real world” testing.

The team of researchers at NC State

Around these infected boxwood, they planted the most promising cultivars from NCSU research in replicated trials. Bennett and others returned to this site several times during the growing seasons to evaluate the degree of defoliation of the boxwood, depending upon weather conditions.

One example of a research plot

It has always been important in the Saunders Brothers, Inc. research trials to select boxwood which consistently showed good results in different trials in different years. As such, many of the cultivars were tested in as many as 5 or 6 different replicated trials.

Bennett Saunders looking over the recently installed 2020 Boxwood Blight research plots immediately after planting

Over a period of eight years, at least 157 different cultivars were tested by Saunders Brothers, Inc. and Kelly Ivors. Through this extensive research, Bennett and the Saunders team saw how many different cultivars reacted to varying amounts of Boxwood Blight pressure in different seasons of the year as well as rainy or dry seasons.

Buxus NewGen Independence® in trial.

Both plants had been in that location for three years. The inoculated plant is on the left.

In the summer of 2018, Saunders Brothers, Inc. felt they had good answers to Boxwood Blight and Boxwood Leafminer problems after well over ten years of intensive research. Saunders Genetics, LLC was created to breed, source, test, evaluate, and market the best boxwood cultivars with consideration to all aspects of culture and garden performance.

Saunders Genetics introduces NewGen® Boxwood

Two plants, unnamed selections at the time, consistently outperformed many common varieties in the trials. Feeling optimistic about finding a solution to the potentially devastating disease, Saunders wanted to share these genetics with the industry, and NewGen ® Boxwood was born.

NewGen Freedom®

NewGen Independence®

NewGen ® aims to be the standard bearer of a distinctively better family of boxwood. This new generation of plants offers improved genetics to the industry and promises better resistance of Boxwood Blight and other boxwood diseases, better resistance to Boxwood Leafminer, and maintains a “WOW factor” in the landscape.

Saunders Genetics looks to continue to be a trusted industry resource on boxwood information by continuing to research and stay up to date on boxwood issues and solutions. Also, by maintaining bio-secure testing methods and standards, Saunders Genetics plans to continue trialing and introducing selections of superior plants that fulfill the NewGen™ brand standards.

Introduced to the market in 2020 were NewGen Independence ® and NewGen Freedom ® . With names that evoke imagery tracing back to 18th century colonial America, where a new country was blazing a trail in history, these plants will lead the industry demonstrating better resistance of Boxwood Blight, resistance to Boxwood Leafminer, and WOW factor in the landscape.

NewGen ® worked to establish both a regional and international network of premier licensed growers and propagators to share these plants in retailers and landscapes across the US. They will continue to expand their network of growers as the market needs arise. The first two introductions, NewGen Freedom ® and NewGen Independence ® , will be available at five wholesale nurseries: Overdevest Nurseries, NJ; Prides Corner Farms, CT; Saunders Brothers Nursery, VA; Willoway Nurseries, OH, and Sheridan Nurseries, Ontario.

NewGen™ Boxwood intends to raise the bar for boxwood to meet the changing dynamics of a new generation of the American garden and gardener. •