As boxwood blight was spreading in the U.S. in the 2010s, executives at Plant Development Services in Loxley, Alabama, and Saunders Brothers Nursery in Piney River, Virginia, were looking for solutions.

Plant Development Services looked to Europe, where blight had been a major issue since 1998, while Saunders Brothers looked to germplasm it had on hand and started focusing on selecting for blight resistance.

Today, thanks in large part to those efforts, several blight-resistant cultivars are available in the U.S. market, and more are expected.

Boxwood blight, a fungal disease that causes leaf spot, stem cankers and defoliation, was first identified in the U.S. with a siting in North Carolina in September 2011. A few weeks later it was found in Connecticut, followed by other sitings on the East Coast as it quickly became a disease of concern.

“We saw it killing these old boxwood plantings at some of the very nice homes and gardens around the country,” said Kip McConnell, business development director for Plant Development Services. “And they were quarantining nurseries, and some nurseries were having to destroy entire plantings when they would find the blight, because there was no cure, and they didn’t have a good program to recognize and prevent it. And so, it was costing nurseries, in particular those in the Northeast and Northwest, hundreds of thousands of dollars.

“That was the trigger that we really need to be looking at this,” McConnell said.

Better Boxwood®

Plant Development Services started its search for a blight-resistant boxwood by reaching out to Didier Hermans, owner of Herplants BV and a well-known breeder in Belgium. Boxwood blight has been a disease of concern there since 1998, when it was first found in Europe.

Hermans had started working with the Flemish Institute for Agriculture and Fisheries Research on developing blight resistant boxwoods in the early 2000s in large part to protect his own business, given that boxwoods were his nursery’s top seller.

“He actually broke down the entire boxwood genus and brought in as much genetic material as he could get from around the world and created a collection of 200 boxwood species and cultivars,” McConnell said. “They started doing hybridizations and testing and trialing to find the ones that were the most blight resistant, and from more than 10,000 seedlings, four resistant hybrids were selected.”

Their efforts resulted in the release of a boxwood-blight-resistant brand called Better Boxwood®, a series of new varieties that McConnell said not only offers blight resistance, but other improved traits.

“They grow really fast, and they have really great root systems,” McConnell said. “That is one of the things we noticed in the very beginning is the root systems on these plants are fantastic. And, of course, that usually makes for a better plant. And so, we’ve been very pleased with that hybrid vigor that they brought, over and above the blight resistance.”

McConnell noted that in a trial in Zone 5 in Ohio last winter, only one of the four Better Boxwood® varieties showed any bronzing, and then only a little. “The other ones had good green color through the winter, which was very good to see because one of the things that a lot of people don’t like to see is winter bronzing on boxwoods,” he said. “So, we are very pleased with that. And there was no cold damage on any of the Better Boxwood® varieties.”

Everde in Orange, California, has partnered with Plant Development Services to bring Better Boxwood® to the U.S. market. Nicholas Staddon, company spokesperson and plantsman, noted that at the Southern California nursery, Better Boxwood® varieties have maintained a dark green color throughout the winter when some of the regular species of boxwoods exhibited a yellow or bronze color.

“We’re seeing the Better Boxwood® program really does maintain a nice, rich green color,” Staddon said.

The Better Boxwood® varieties also meet a range of needs, from the Renaissance™ (Buxus × ‘HER200B01’ PP32274), a low-growing shrub ideal for low hedges, to the Skylight™ (Buxus × ‘HER2009B03’ PP32275), a tall variety suitable for topiary and medium hedges. The Renaissance™ grows 1–2 feet tall and wide, with dark-green leaves, while the Skylight™ grows quickly and is easily maintained at  3–8 feet tall and 3–4 feet wide, with medium-green leaves.

In between are the varieties Babylon Beauty™ (Buxus × ‘HER2010B04’ PP32273), which grows 3 feet tall and  4–5 feet wide and has light-green leaves; and Heritage™ (Buxus × ‘HER2010B02’ PP32309), which grows  3–4 feet tall and 2–3 feet wide, with dark green leaves and is ideal as a hedge or pruning form.

A key to bringing the plants to the U.S., according to McConnell, has been the partnership Plant Development Services formed with Everde Growers, which has which has 15 farms and 6,000 acres in production across the country, including at multiple sites in California, Florida, Texas and one site in Oregon. Together, the companies formed Boxwood Solutions Inc.

“Everde’s production power and Plant Development Services’ track record in introducing new plants, helped persuade Hermans to work with Boxwood Solutions as its sole distributor of Better Boxwood in the U.S.,” McConnell said.

Better Boxwood™ debuted in the Southeast markets this past spring, and more will be available this fall and in spring 2025, McConnell said. Approximately 40 growers across the U.S. are licensed to propagate and market the four varieties, according to Staddon. And Plant Development Services also is working with JRT Nurseries in British Columbia to represent Better Boxwood in Canada.

NewGen® Boxwood

At Saunders Brothers, work started on a identifying a blight-resistance boxwood in 2012.

“Our signature plant for 75 years has been boxwood,” said J. Bennett Saunders of Saunders Brothers Nursery and General Manager of Saunders Genetics LLC. “And when blight hit in 2011, we knew we had to do something if we were going to stay in business, because we quickly found out that most of the cultivars we were growing were fairly susceptible to blight.”

The nursery started focusing on blight resistance in its replicated, multi-season trials, Saunder said.

“People have been giving us plants for years to test, because they know we are into different varieties,” Saunders said. “And so, we already had one mutation and one plant that a friend had given us that had good resistance to blight and the boxwood leafminer, and we quickly got those going within our program.”

Saunders added that in addition to testing for boxwood blight resistance and leafminer resistance, observations are made regarding resistance to other pests and diseases, as well as grower and garden friendliness.

Today, the company has three blight-resistant boxwood varieties available, marketed under the brand NewGen®, all with leafminer resistance, as well.

NewGen Freedom® (Buxus ‘SB 300’ PP32421)  is a boxwood Saunders Brothers released in 2018 that is fast-growing with deep green foliage that tends to be more compact than some boxwoods and is easy to shape. “It is a vigorous grower, so we strongly recommend annual pruning to encourage branching,” Saunders said.

Saunders described NewGen Independence® (Buxus ‘SB 108’ PP28888), a second boxwood that the company released in 2018, as a high-gloss leaf plant with more of a classic boxwood look. “It is just a really beautiful boxwood,” he said.

The third variety, released the summer of 2023, is NewGen Liberty Belle™ (Buxus sinica var. insularis ‘RLH-BI’ PP24443), a plant Saunders described as a little slower growing with a “billowing” shape that makes an excellent shade specimen. He added that Liberty Belle™ “has shown outstanding blight resistance in our trials.”

Saunders Genetics also expects to release a cold-hardy boxwood with blight resistance in the next year or two.

“We have teamed up with a breeder in Wisconsin, Mike Yanny, and we are testing his selections, which are considered more cold hardy,” Saunders said. “We’re looking for the same criteria we are with other boxwoods — attractive plants with insect and disease resistance plus grower friendliness — but add to that cold hardiness. We are very excited to offer that combination of traits to our more northerly growers and their customers.”

To date, the NewGen® Boxwood cultivars are popular sales options in the East and Southeast, and they are gaining in popularity in the West and in the Midwest, according to Ken McVicker, sales manager for Woodburn Nursery & Azaleas in Woodburn, Oregon, which is licensed to grow and sell the varieties.

“I think there is room in the market for more NewGen® boxwood sales,” McVicker said. “It’s very popular in the Southeast and on the Eastern Seaboard. It’s less known out in the West at this point and in the Midwest. But I think with the work that NewGen® is doing in its awareness program — their education, their advertising and marketing — it’s gaining more popularity throughout the country.”

Saunders added that the company is expanding its network of licensed growers, noting it now has 33 licensed finishers with right-to-propagate. “Plus, liners are available through Decker’s [Nursery], Spring Meadow and Briggs,” he said.

Management practices

As for the future of the boxwood blight-resistant varieties, sources said it will be imperative for nurseries to use best management practices when increasing and maintaining supplies of the varieties.

“I will say to maintain a really good quality boxwood, the cuttings only should be taken from the very best quality plants,” Staddon said. “It is imperative that the cuttings come from the very best stock that is available to us.”

Saunders noted that Saunders Brothers and Saunders Genetics have long collaborated with the research and outreach efforts of the Boxwood Blight Insight Group and the Horticultural Research Institute of AmericanHort in support of best management practices.

“We have all along stressed best management practices, especially sanitation, and also to use more blight-resistant cultivars,” Saunders said. “We’ve been saying that since 2011 and we continue to say that.”

Working with Keith Yoder, who leads the company’s inhouse breeding program, Saunders Genetics also is continuing to evaluate thousands of seedlings for blight resistance.

Saunders added that he believes the industry has made huge strides in blight mitigation over the last decade. “It’s very quickly becoming a managed disease, not the plague that’s going to kill your business,” Saunders said. “As with other insect and disease issues, you’ve just got to change some of your management practices and utilize more resistant varieties.”

From the September 2024 issue of Digger magazine | Download PDF of article