Part 2 - Trialing, Trialing, and More Trialing
by Holly Scoggins, Program Manager, NewGen® Boxwood
In Part 1, we shared how NewGen® is working with talented breeders to bring more varieties to market. But before becoming part of our boxwood brand, any selection of interest goes through a very long haul of trialing for good resistance to boxwood blight (Calonectria pseudonaviculata), boxwood leafminer (Monarthropalpus flavus, a serious issue in the Mid-Atlantic), and to get a good look at mature habit and performance to ensure the WOW factor. But wait, there’s more! A multi-year biosecurity gauntlet provides clean material for propagation and production.
As described in Part 1 - we’ve got some really promising selections in the pipeline from our breeders. So what happens next?
The boxwood blight trials field is designed to put the highest blight pressure on potential selections.
In a blight-infested field, far, far away from Saunders Brothers Inc. (seriously, like, three hours away), selections of interest are planted out in replicated trials. In this environment, we are actually encouraging blight, so overhead irrigation is needed. Beginning in early August, misters run every evening between 7:00 p.m. and 11 p.m., when temperatures are in the 60 to 70 degree range. This environment is perfect for blight infection and spread. Boxwood blight data is taken several times through the early fall as the blight gets worse, including level of defoliation and percentage of leaves infected. Promising resistance results gains a selection another year in blight-land, before it is judged worthy of moving forward.
All along the way, size, habit, and landscape performance are taken into consideration and must be superior to other varieties. Dubbed the “WOW factor” by patriarch Paul Saunders, Bennett and the rest of the Saunders family of boxwood experts won’t introduce anything they wouldn’t showcase in their own gardens - perhaps the toughest hurdle for any selection!
As boxwood leafminer was an issue prior to boxwood blight - and remains as such - multi-season trials for resistance to this troublesome pest occurs simultaneously. Selections are planted into decades-old, unsprayed test beds away from the main nursery, guaranteeing loads of leafminer. Leafminer resistance plays a large role in whether or not a plant moves forward.
Another factor in the timeline? Biosecurity concerns for container and field production at Saunders Brothers Inc. With zero tolerance for boxwood blight and strict visitor policies, SBI remains blight-free. To help keep it that way, any promising new selection emerging from the previous trials goes through a multi-year, multi-location process to make it into production and onto the NewGen® roster.
Once a selection is judged to fit the NewGen® model of pest and pathogen resistance plus the WOW factor, cuttings are taken, sanitized, and rooted as it starts the journey from Level 4 (the trials area known to have blight) to a clean hoophouse located miles away from the nursery (Level 3). With overhead irrigation and no sprays, if blight was present it would manifest here. In the quarantine areas, containers of Buxus sempervirens ‘Suffruticosa’ are scattered throughout as the highly-susceptible “canary in the coal mine” If two summers in quarantine yields zero blight, the selection is moved into high-security NewGen® greenhouses (Level 2) but must remain there for an additional year before moving into commercial production (Level 1). This four-level system ensures the highest security and confidence of cleanliness for both SBI products and as the selection is propagated.
Taking into consideration that boxwood are slow growers to start with, this process is not for the impatient. A seedling selection is looking at a 6- to 10-year stint in the NewGen® and Saunders Brothers pipeline before deemed ready for prime time!