Winter and Boxwood: Bronzing

Several species of broad-leaved evergreens and conifers exhibit winter orange-to-purple coloration, referred to as "bronzing." The production of chlorophyll slows, so purple-to-orange anthocyanin pigments present in the leaves are more visible. Drought stress resulting in decreased transpiration can exacerbate the situation. The discoloration can appear on just the tips, one side, or the whole plant. Whether Buxus, Chamaecyparis, or other species, this pigment change is not harmful to the plant. Bronzing is easily distinguishable from other issues, as most diseases either attack lower foliage, cause defoliation, or result in an obvious discolored branch or sector of the plant, not a relatively uniform color change across the surface - dig into a bronze boxwood and you should find plenty of green.
 
The desiccating effects of wind and sun can result in bronzing as a stress response, especially if the plant is already drought-stressed.  Full-sun exposure tends to result in a greater degree of discoloration – and if in partial shade, the “sunny” side may be bronze. Multiple freeze/thaw cycles and south to southwest exposure present the greatest chance of bronzing.  Boxwood planted in a more protected area including the north or east side of a structure are more apt to avoid bronzing.   

Example of bronzing on Buxus sinica var. insularis ‘Franklin’s Gem.’ This specimen is located on the southwest side of a building – partly shaded by deciduous trees in summer, but quite sunny in winter.

Species and cultivars of boxwood vary as to the degree of bronzing. Note bronzing is not an indicator of a lack of cold hardiness.  Buxus x ‘Green Gem’ tends to bronze with full sun exposure but is one of the hardiest boxwood, rated to USDA Hardiness Zone 4. Our own NewGen Freedom (cold hardy to Zone 5) can also bronze if planted in full sun, especially if south-facing and exposed to wind, but seldom suffers cold damage such as desiccated shoot tips. Variegated boxwood may only show discoloration on the light-colored leaf margins. The good news for any discolored boxwood is the rapid recovery in spring when warmer temperatures and ample moisture boost chlorophyll production. Green is right around the corner!

---

The lemon-lime leaf margins of some variegated boxwood such as Buxus microphylla Golden Dream (‘Peergold’) take on an orange cast when temperatures drop. The crisp color contrast returns in spring with warmer temperatures.  

Winter and Boxwood: Diagnosing Cold Damage

We all love boxwood for the beautiful evergreen (and deer-resistant) foliage, but winter injury and discoloration can certainly occur. In this newsletter and the next, we’ll discuss some common issues – fitting, considering the winter we’re having (with more yet to come).
 
We divide cold damage into two camps: frost damage that occurs in fall or spring, resulting in light die-back of the newest growth; and more severe freeze damage because of unusually low or prolonged cold temperatures. Buxus species and/or cultivar cold hardiness is important to note, as there is a fairly broad range of cold tolerance among species. The degree of damage can vary by exposure (sun to shade) and the relationship to topography or structures. Boxwood with southwest-facing, full sun exposure seem to be at greater risk of damage.

Maintenance timing matters as well: early spring or late summer pruning or shearing can stimulate new shoots that will get damaged if there’s not enough time to harden off before a frost or freeze. 

What does cold damage look like? Pale- to straw-colored, desiccated foliage and branch tips, usually at the top and outer tips of the plant. Fresh young shoots are especially susceptible (recall boxwood blight symptoms often first appear in the interior lower branches and base of the plant, as spores spread by rain splash). Additionally, an extreme freeze event in fall or spring can cause splitting of bark - resulting in dead limbs. Snow cover can be fantastic for protecting both foliage and branches if it’s a strongly branched plant. 

This lovely cloud-style planting of Buxus microphylla ‘Green Pillow’ (Zones 6-9) is in full sun located on the west side of the residence. Sun and wind conspired with an extended hard freeze to desiccate the upper, outer foliage. Once growth resumes in the spring, the plants may benefit from a bit of shearing. 

---

NewGen Independence® (Buxus ‘SB 108’ PP28888) (Zones 5b-8).  Last pruned in July, a warm, wet September encouraged a few fresh shoots. Alas, an unusual early-October frost blasted the tender growth. Simply snip these pale shoots off once the danger of frost has passed in the spring.

Behind the Fluff: Boxwood Psyllid

For much of the U.S.,  boxwood leafminer (Monarthropalpus flavus) is the most prevalent and destructive pest of boxwood. So much so that one of the main criteria for selection of our NewGen® cultivars has been for superior resistance to boxwood leafminer.

But what are these white fluffy bits scattered amongst new growth? The culprit is Psylla buxi, the boxwood psyllid. Nymphs emerge in April to May across much of their range.  The white filaments are secretions that can serve as “cover” for the larvae.

Those aren’t snowflakes! Note the fluffy white secretions from boxwood psyllid nymphs.

As a piercing and sucking pest, they’re after the sap from soft young foliage or unopened buds. The damage from feeding action can result in inwardly cupped foliage at the tips of the branches. The nymphs mature rapidly, with the adult resembling a little leafhopper or tiny cicada. Eggs are laid into bud scales to start the process over the next year. 

Nymph photo (left) courtesy of Nancy Gregory, University of Delaware, Bugwood.org

Damage photo (right) courtesy of Penn State Department of Plant Pathology & Environmental Microbiology Archives , Penn State University, Bugwood.org

The good news? Damage, if visible, is only cosmetic.  Several sources note American Boxwood (Buxus sempervirens, straight species) seem to be the most likely to show damage.

One option is to “let it be” as there are many natural predators that snack on psyllid.  Another is to lightly shear off the boxwood tips in early spring, prior to larvae emergence.  Insecticidal soaps or horticultural oils work if applied prior to spring flush. If just a few of the pests are visible, never underestimate the utility of a strong spray/stream of water directed at infested areas.  If you’re already using a systemic for control of leafminer, psyllids probably aren’t an issue. Always consult your state or provincial authorities’ pest management guide or other regulatory agency for information on labeled chemicals for a specific pest.  

"What's Up With My Boxwood?" - Late Winter Edition

Author: Holly Scoggins, Program Manager

Many of us experienced a relatively warm late fall and early winter. Late December in my own Southwest Virginia garden (Zone 6b, 2100’ elevation) saw some perennials emerging that had no business even peeping until early spring, plus a bit of new growth on some evergreens. Then blammo! Temperatures dropped dramatically, winds increased, snow and ice became the norm for January, and the first half of February hasn’t been much better. What an excellent time to review a few common winter issues for boxwood! Note that as with most things Buxus, susceptibility to abiotic or biotic issues is usually species- or cultivar-specific.  Start with cultivars that are cold-hardy in your geographic region – check tags and other resources as to USDA cold hardiness zone.  Here are a few of those frequently asked questions.

FAQ #1: What’s up with the cream/tan/straw-colored foliage at the tips of branches?

New growth can be susceptible to cold damage, resulting in bleached or desiccated foliage.

Chances are this was new growth that hadn’t had the chance to harden off. The same damage can occur on fresh growth in spring that gets hit by a late freeze. Gradual acclimatization to cold (and then to warm) is ideal but doesn’t always happen. And as with many woody plants, don’t encourage late-season growth. Fertilizer applications and pruning in late summer and early fall can stimulate fresh foliage that is susceptible to damage. Be sure landscape or nursery plants are well-watered going into an extreme cold spell to limit desiccation. While this bleached foliage is unattractive, rarely is the health of the plant compromised. Simply snip off damaged foliage and twig tips in spring.

FAQ #2 Should I remove the ice and/or snow weighing down the branches?

Buxus sempervirens branches can bend under the weight of significant snowfall. 

Nothing insulates and protects hardy plants better than a nice blanket of snow.  However, rarely is the snow deep enough to completely cover shrubs. The weight of snow and ice over exterior branches can cause them to snap or split.  The chance for damage is exacerbated by whacking at the wintery build-up with a broom or shovel – a too-common practice. Let it melt naturally if possible.  If additional snow and/or ice is expected to the point of concern for breakage under the load, remove by gently shaking or brushing with gloved hands. 

FAQ #3:  Why is my boxwood foliage bronze/orange in winter? 

Bronzing happens!

“Bronzing” is the boxwood term for the appearance of purple-to-orange anthocyanin pigments that can occur in winter. The discoloration can affect one side, the whole plant, or just the tips. Bronzing is much more likely to occur on boxwood planted in full sun, especially with southwestern exposure. The pigment change is not harmful to the plant, as the foliage greens up in the spring – but you may consider a shadier or more appropriate site for that specimen. Again, susceptibility to bronzing is a bit cultivar-specific. If the aesthetics of bronzing are an issue and your boxwood will be sited in full sun, pick a cultivar shown to be less prone to the condition.

For a list of cultivars and much more information on winter care of boxwood – visit the NewGen® Boxwood site https://www.NewGen®boxwood.com/boxwood-care#winter

Fall is for Planting...Boxwood!

By Holly Scoggins and J. Bennett Saunders

The cooler, wetter months of autumn are an ideal time for planting woody ornamentals and herbaceous perennials, especially boxwood (Buxus species and cultivars). Let’s review some cultivar selection tips and best practices for design, planting, and aftercare. 

Boxwood, historically the aristocrat of shrubs, remains a popular choice for more formal landscapes. Though substitutes are touted, nothing tops the lush evergreen foliage, shape-ability, and that irreplaceable quality of deer-resistance of boxwood.  

The quiet sophistication of boxwood in a formal garden is unmatched, and best management practices will help keep them healthy and beautiful. (photo courtesy of Tom Belden, John Richmond Landscaping, Inc.)

Boxwood do have a few important pests and pathogens. Regarding pests, boxwood leafminer (Monarthropalpus flavus) is an issue across much of the United States. Box tree moth (Cydalima perspectalis) has made its way to North America. Boxwood blight Calonectria pseudonaviculata is taking its toll on boxwood in eastern North America as well the West Coast. The fungal disease thrives with mild temperatures (60°-77°F) and wet conditions and can survive for years in infected plant debris. However, there are several keys to optimizing boxwood health in the landscape and reducing the chance of boxwood diseases and pests —cultivar selection, attentiveness to mature size/spacing and site selection.

Which Boxwood?

Success starts with plant selection. No boxwood variety can claim complete resistance to both boxwood blight and boxwood leafminer, but research trials and field experience with more than 130 varieties reveal some common-sense selections.  To cross off the list: Buxus sempervirens ‘Suffruticosa’ (European or English Boxwood) - a “plant of the past” that is highly susceptible to boxwood blight - many good alternatives exist.  Buxus sempervirens (American Boxwood) cultivars vary in their landscape performance and degree of blight and leafminer resistance. However, Buxus microphylla varieties topped resistance rating and are thus a good choice for blight-prone areas that also experience leafminer.  The cold-hardy Buxus sinica var. insularis  hybrids such as ‘Green Velvet’ show some resistance to boxwood blight but susceptibility to boxwood leafminer. A terrific source of cultivar-specific information is the beloved “Boxwood Guide” published by Saunders Brothers Inc. and now in its 6th edition - PDF available for free - download at https://www.saundersbrothers.com/page/Boxwood-Guide

All cultivars listed below exhibit reasonable resistance to both boxwood blight and boxwood leafminer. 

·      Low hedges and other edging purposes call for dwarf cultivars, such as B. microphylla ‘Little Missy’ and B.sinica var. insularis ‘Nana’. Always confirm mature size of a cultivar.

·      For classic green orbs as specimens or foundation plants in the 3-to-5-foot range, consider NewGen Freedom® (Buxus ‘SB 300’ PP324421) or NewGen Independence®  (Buxus ‘SB 108’ PP28888),  both of B. microphylla heritage. Buxus microphylla var. japonica ‘Green Beauty’ is also a durable choice but may require leafminer management. When a gold variegated form is desired, B. microphylla Golden Dream (‘Peergold’PP16052) shows reasonable resistance to both issues. 

·      Upright boxwood are irreplaceable for vertical interest. Though a bit more susceptible to blight in trials, B.sempervirens cultivars ‘Dee Runk’ and ‘Fastigiata’ remain popular. When used for vertical interest, proper spacing and placing them in a location with good airflow can help mitigate boxwood blight.

Boxwood plays well with others! Orbs of boxwood NewGen Independence® and a hedge of ‘Little Missy’ compliment the sparkling summer blooms of Oakleaf hydrangea (Hydrangea quercifolia ‘Munchkin’). (Photo courtesy of Paul Westervelt, Saunders Brothers Inc.) 

Site Selection, Spacing, and Installation

When considering placement, note sun tolerance varies by cultivar. Afternoon shade is optimal.  Another siting consideration—high and dry(ish) if possible. Boxwood appreciate well-drained soil and will struggle with wet feet. Good drainage minimizes the chance for Phytophthora and other root zone diseases. 

As with any other landscape ornamentals, confirm cultivar-specific mature size when spacing to ensure long-term satisfaction with the project. What will the garden look like in 10 to 20 years?  

For a border or other row-type application, clipped hedges are perpetually popular, but consider the “pearl necklace” approach as well—generous spacing allows for air movement, a key to reducing the potential for blight. If utilizing boxwood for a foundation planting, ensure sufficient spacing away from the structure and place well away from downspouts to maximize air circulation and minimize potential for a wet rootzone.

When installing, pay particular attention to best planting practices. Planting the top of the root ball approximately 2 inches above ground level, a bit higher than the soil line, helps ensure proper drainage. 

Boxwood blight research has demonstrated that a light layer of mulch (one inch the first year, one-half inch per year thereafter) will reduce splashing of precipitation that might carry spores—boxwood blight spreads easily via mechanical/water movement. Overhead or other spray irrigation is discouraged for the same reason; drip irrigation is preferred. If hand-watering is required, direct your client to water the soil, not the foliage. Immediately after transplanting, water thoroughly again and continue to monitor moisture for 18 months or so, until the plant is established. Once severely drought-stressed, boxwood seldom recovers completely. 

Here’s an example of proper selection and spacing for optimal air movement with Buxus microphylla var. japonica ‘Jim Stauffer’. The light layer of mulch prevents water splash and lessens potential for the spread of boxwood blight.  (Photo courtesy of J. Bennett Saunders, Saunders Genetics, LLC). 

Transplant Tips

If a client has a beloved (and healthy) specimen boxwood that requires relocation, fall is the best time for transplant efforts. Some landscapers have success transplanting during mild winters, particularly in USDA Plant Hardiness Zones 7-9. Proper timing will allow for maximum root growth when moisture is typically more abundant. This in turn better prepares the plant for dry summers. 

Increase chances of success by adequately watering the plant prior to any digging. The root ball should be dug as wide as the canopy of the plant (at a minimum). The root ball size will vary but a rule of thumb should be for every one foot in width, the depth should be six inches. Since boxwood have shallow roots, greater focus should be on root ball width than depth. 

As with any transplant project, do not leave the boxwood above ground for a long period, especially in times of extreme heat or cold. Never allow the root ball to dry out. Never move boxwood during the stress of summer heat or severe drought.

Sourcing Plant Material

To conclude, here are a few final thoughts on sourcing. Departments of Agriculture for many states maintain a boxwood blight cleanliness program along with a compliance agreement for nurseries. These agreements describe comprehensive best management practices to be followed. Source boxwood material from nurseries listed! These nursery growers uphold the highest standards of sanitation and best practices to keep boxwood blight out of the supply chain.  

For in-depth resources and tips on boxwood care for both homeowners and landscape professionals, visit www.newgenboxwood.com.

A similar version of this article by Holly and Bennett appeared in the digital newsletter of the Association of Professional Landscape Designers, August 2021. https://issuu.com/designonline/docs/apld_design_online_august_2021

Japanese Maple Scale Becoming More Problematic

File under “if it’s not one thing it’s another...”  Japanese Maple Scale (JMS) (Lopholeucaspis japonica) has been around for decades but seems to be of increasing concern for nurseries and landscapes. The armored-scale pest damages plants with piercing-sucking mouthparts, causing cells to rupture/collapse, resulting in eaf drop and branch dieback. Moreover, it is a  pest of a very wide range of woody ornamentals (over 45 genera), including Buxus.  Understanding the life cycle of JMS is critical to identification and management - see below for resources explaining the complexity thereof. 

Infestation of Japanese Maple Scale on an interior branch of boxwood. Note the elongated white scale "armor." Photo courtesy of J. Bennett Saunders.

The armored cover of an adult has a waxy coating rendering treatment difficult. This coating (called a “test”) may also make identification as it is similar in appearance to other scales. Compounding the issue:  multiple life stages can be present at once, and multiple generations accumulate and build in older interior wood.   Cooler areas see two generations; warmer mid-South areas may see more.   Stanton Gill, IPM and Entomology Specialist with University of Maryland Extension, has been working on regional JMS for quite a while. It has since made it as far west as Indiana and Ohio, according to Gill.  Bennett Saunders noted he’s seen it impact primarily two Buxus sempervirens cultivars - ‘Dee Runk’ and ‘Fastigiata.’

Japanese Maple Scale damage, including branch die-back, on Buxus sempervirens ‘Dee Runk’

We asked Gill for a status check at the end of August: “We are in the middle of the second generation [and it] appears to be on the increase in the nursery trade this season.”  Along with the eponymous host, Gill and colleagues are receiving reports of it in both nurseries and landscapes on boxwood, blue holly [Ilex x meserveae and cultivars] and American holly [Ilex opaca and cultivars]” among other taxa. Gill reiterated the very wide host range and urged nurseries and landscapers to be vigilant.  Degree days and careful scouting can be used to detect the crawler stage - the non-armored, most vulnerable stage of development that responds to chemical control measures.

One means of control is mechanical - high-pressure water spray, along with a gentle scrub brush - and one of the best options for homeowners who may have a few shrubs or trees with lower levels of JMS. There are also parasitoids (beneficial insects) that attack JMS - their presence can be detected by tiny holes piercing the scale covers. In order to preserve populations of beneficials, don’t utilize topical insecticides - there are other options.

For the current situation in nurseries or professionally-managed landscapes, Gill says “Distance and Talus are two good Insect Growth Regulators  (IGRS).”  In late fall (no tender leaves on boxwood), he recommends coming back with a 1 - 2% horticultural oil to go after the overwintering second instar males and females.  Due to potential phytotoxicity, always test oils on a small number of plants before more extensive application. Read and follow all pesticide label directions carefully. 

The above recommendations are based on the Mid-Atlantic location, always check your state’s Cooperative Extension pesticide management information for management recommendations and adjust the timing for your locale.  For more information on Japanese Maple Scale, please check out these resources:  

Boggs, J. 2020. Japanese Maple Scale (JMS). https://bygl.osu.edu/index.php/node/1554

Frank, S.  2017. Japanese maple scale management. Nursery Management. https://www.nurserymag.com/article/japanese-maple-scale/

 Frank, S. 2017. Take up arms. Nursery Management https://www.nurserymag.com/article/take-up-arms/ 

Gill, S. and P. Shrewsbury. 2021. Japanese Maple Scale: A Pest of Nursery and Landscape Trees and Shrubs (FS-967) https://extension.umd.edu/resource/japanese-maple-scale-pest-nursery-and-landscape-trees-and-shrubs-fs-967

Any reference to commercial products, trade, or brand names is for information only, and no endorsement or approval is intended. Always refer to tables and information in your state’s Pest Management Guide for active ingredients and trade names of any chemical products.  State regulations may vary - always remember “the label is the law.”

Boxwood Health Check-up at the White House!

As many of you know, Saunders Brothers Inc. supplied over 400 top-quality boxwood, including 350 NewGen Independence® for the 2020 Rose Garden renovation at the White House (but you may not be aware that Saunders Brothers also provided 1,500 boxwood for the original 1962 design during the Kennedy administration). Bennett was invited back in late May to assess the condition of boxwood on the grounds.

After passing through security checks, we joined White House grounds and horticultural staff on an inspection of the new planting where Independence® anchor and define the beds lining the lawn. We are thrilled to report they look fantastic – kudos to the hard-working staff for their outstanding care!

As the day warmed up and cicadas buzzed in the background, we also toured the multitude of boxwood plantings throughout the grounds. Bennett discussed spray schedules and shared other maintenance tips with the staff, and diagnosed issues with some older boxwood. Many have been in place for 50+ years while others are more recently planted. We appreciate the opportunity to assist these dedicated horticulturists who strive to balance the new with the profoundly historic. All in all, an amazing morning in D.C.!

As photography of any structure (and most everything else) was prohibited, Holly was allowed only a quick iPhone close-up of the planting. Check out the healthy, glossy new growth on NewGen Independence®! The roses were also filling in and interplanted with pollinator-attracting perennials and annuals.

Cleaning Up Boxwood Blight in the Landscape

Late summer through mid-fall is the most likely time to see Boxwood Blight in landscapes.  Shorter days, splashing rains, ideal temperatures from 60°-77° F, and slower drying create an environment in which the disease thrives. Be on the lookout!

Since 2011 when Boxwood Blight was first discovered in the United States, there has been a great deal of research and much has been learned regarding control and living with the disease. The earliest assumption was that any landscape infected by Boxwood Blight would need to be destroyed, however; research has shown there are many steps that can be taken to clean up Boxwood Blight properly. If certain steps are taken early, many landscapes of Buxus sp. can survive and even thrive after Boxwood Blight.

Rubber boots are easily cleaned after being worn in landscapes containing boxwood.

If Boxwood Blight is suspected:

• Take samples to testing labs and limit access to the area until results are obtained.

If you suspect the disease in the landscape, you should take great care in collecting samples by double bagging them and taking them to the local Extension office or another testing lab. The area should be roped off or temporarily fenced off until the results are obtained.

If Boxwood Blight is confirmed:

• Take great care not to further spread disease.

• Do cleanup on dry, sunny days when foliage is dry.

• Consider fungicide applications before and during cleanup to control spread.

• Wear rubber boots and disposable clothing during cleanup to lessen contamination of clothing and shoes.

• Cut and place the infected plants in a plastic bag and take care to minimize leaf litter.

• Clean up as much leaf debris as possible. Roots are not believed to carry Boxwood Blight.           

• Debris should be burned or taken to landfill with care to not let leaves escape.

• After cleanup, wash skin, launder or dispose of outer clothing, and wash boots.

• Increase airflow in and around remaining plants by thinning and removing lowest limbs.

• Do not bury debris as the disease can survive in the soil for long periods of time.

• All tools and equipment should be thoroughly cleaned when moved between different gardens or areas.

• Mulch to lessen the splashing of spores.

• Replant with cultivars that are more resistant to Boxwood Blight.

• Monitor boxwood in times of optimal conditions for new infections and flare-ups.

Crews at Saunders Brothers, inc. wear disposable clothing to help avoid introduction of Boxwood Blight that may enter the nursery on their clothing.

If Boxwood Blight is confirmed, you must be diligent and careful in cleanup. Extreme care should be taken to avoid infecting other plants. Choose a time to cleanup when it is sunny and when foliage is dry. The plant is less likely to be sporulating when foliage is dry. Consider applying fungicides to any area where you are working to kill any spores that are present.

Always wear some sort of disposable suit, like disposable Tyvek® coveralls, and rubber boots as they can easily be cleaned. If possible, put a plastic bag over the infected plant and cut the plant off at the base. Take care to catch as much leaf litter as possible. Then, clean up any leaves that fall before disturbing the soil as you do not want to incorporate diseased debris into the soil. After all debris is cleaned up, remove the roots. All debris should be bagged or covered to eliminate the possibility of it blowing or falling out. Do not compost the debris. Burning the debris is the best possible option.

The most effective way to sterilize soil is to burn any debris around the base of the infected plant.

After the cleanup is complete, remove outer clothing and launder or dispose of it. Laundering with detergent and hot water will kill spores. Boots should be thoroughly washed, and all tools and equipment should be carefully cleaned as well. Prune any other boxwood in the landscape to increase airflow to maintain dry foliage. Remove any limbs that touch the ground and might get rain splash, and be sure plants are properly mulched. Continue to monitor the boxwood during environmental conditions conducive to infection.

If planning to replant with boxwood, be sure to choose cultivars that are more resistant to the disease. Saunders Brothers, Inc. and Saunders Genetics have tested and trialed boxwood in search of varieties and cultivars that prevail against Boxwood Blight.  Buxus sempervirens ‘Suffruticosa’ (English boxwood) is the most susceptible cultivar, whereas Buxus microphylla, Buxus insularis, and Buxus harlandii species and cultivars tend to have more resistance. It is difficult to completely define groups based on species as we have found exceptions based on plant architecture and structure. Open, more upright plants tend to be less susceptible while short, compact cultivars seem to be more susceptible. NewGen Independence® and NewGen Freedom® offer strong resistance to Boxwood Blight as well as fantastic landscape appeal.

Once the landscape is cleaned and replanted, diligently monitor plants to catch any early signs of re-infection. With a combination of careful clean up, replanting with resistant cultivars, and best management practices to avoid Boxwood Blight, landscapes of Buxus sp. can continue to flourish after Boxwood Blight.

NewGen Freedom® in the field.

Being Water Smart with Boxwood

Older boxwood that are established in the landscape can survive longer periods of drought because of their more extensive and established root systems.

As we trudge through the peak of summer heat, irrigation and water is on everyone’s mind. In Central Virginia, it is common to see several weeks of unforgiving heat which can lead to dry soils and drought. Summer showers that sweep through offer some relief but rarely are absorbed into the ground enough to really help a boxwood.

The arrows show holes on the drip tape where the irrigation water escapes.

It is important to have plants in the landscape that can tolerate the ebbs and flow of the seasons. Boxwood are known for their toughness and their drought tolerance which makes them a great addition to any landscape. However, just like any plants, they have their limits, and extended periods of drought can require supplemental water. Pay close attention during these hot and dry summer months, so that boxwood do not stress. For the first 1-2 years after planting, boxwood grow best with about 1” of irrigation or precipitation a week during the summer months. Allowing the root zone to dry between irrigation events will encourage root growth. Older plants that are well established generally need minimal irrigation because their roots are deeper in the soil.

The black drip tape that runs along the mulch at the base of the plants provides water directly to the roots of the boxwood.

Drip irrigation is the ideal method for watering boxwood. Simple drip systems can be installed either on top of or under the mulch and will offer thorough irrigation without wetting the foliage. In a drip system, water seeps from the drip tape without splashing. It enters the ground without puddling and conserves water. The rate of water from drip tape is very low, typically ¼”  per hour per emitter. With almost direct access to the roots, less water is wasted thereby reducing costs and environmental impact. Drip irrigation is ideal for places where water may be limited during times of drought.

Not only is drip irrigation more cost effective and beneficial to the environment, it is better for the plant because it drastically reduces the amount of water that splashes onto the leaves of the plant. Fungal diseases such as Boxwood Blight can be spread through water splashing that often occurs with sprinkler methods of irrigation.

Drip tape is commonly used in field production because of the benefits to the plant and the reduced costs on the environment.

If a drip system is not an option, overhead watering is still acceptable, but it is important to take precautions to protect the plants. Make sure overhead watering takes place in the early morning, giving the leaves ample time to dry. Never water boxwood in the late afternoon or evening because wet foliage through the night can lead to diseases and stress on the plant. Be careful not to overwater or let water pool around the roots for too long, as it can lead to root disease like Phytophthora.

It is important to be smart when watering boxwood. Remember that they can tolerate drought but like anything, they have their limits. Boxwood that show signs of stress from either too much or too little water are unforgiving.  Pay attention to provide the appropriate amount of water and boxwood will continue to provide elegant structure to the landscape for many years to come!

July 2020: Now is the Time to Treat for Boxwood Leafminer

Adult females deposit fertilized eggs through the underside of the tender new boxwood leaves.

Although boxwood are known for their low maintenance and tend to have few pests, Boxwood Leafminer (Monarthropalpus buxi) can be a challenge for growers in the Mid-Atlantic region and around the United States. Technically a midge, not a leafminer, this pest causes damage that starts small as discolored leaves but can become severe as populations build over a period of years. Luckily, this tiny orange insect has only one life cycle per year, providing easy and effective ways to treat it.

View fullsize

The life cycle begins in the early spring as the previous year’s larvae pupate and cause the boxwood leaves to discolor, blister and swell. Those pupae emerge as adults in April/May (in central Virginia), hovering only inches above the boxwood due to their weak flying abilities. Over an approximately 3-week period, adults emerge in waves to mate. Females then complete their life cycle after they lay eggs in the tender underside of the new boxwood leaves. These eggs hatch in early summer (mid-June in central Virginia) and the larvae begin the cycle of growth that will conclude the following spring.

Photo taken July 1: The young Boxwood Leafminer larvae are only visible under a microscope.

These early instars are very small, see them here compared to a pin head.

Chemical controls are the best alternative for complete treatment of Boxwood Leafminer. It is unnecessary to time a chemical application that successfully kills Boxwood Leafminer adults because the adults emerge over several weeks and live only several days, requiring multiple sprays. The larval stage provides a much longer spray window and is likely to be significantly more effective. The eggs hatch around mid-to late June in central Virginia, and the larvae are eating and growing, during the summer and fall. Research has found systemic insecticides to be effective in killing larvae until temperatures turn cold, which in some years is not until late October or early November. This strategy can provide control for up to 2-3 years as a thorough spray totally wipes out the population.

Severe blistering and discoloration are the result of heavy Boxwood Leafminer populations.

Boxwood Leafminer adults are small, orange, mosquito-like midges, that are often found hovering only inches from the foliage because they are weak flyers.

For Boxwood Leafminer control, growers have had excellent success with products in the neonicotinoid group that contain the active ingredient imidacloprid, thiomethoxam, or dinotefuran. There is a great deal of ongoing discussion regarding neonicotinoids and other chemicals and their possible effect on pollinators. Nurseries and gardeners should follow good science and alternative methods to control these pests to further eliminate use of this group of pesticides. All growers should minimize the use of any pesticide by practicing Integrated Pest Management or IPM. The goal of IPM is to effectively control a pest while minimizing negative impacts on pollinators, the environment, and employees.

Examples of insecticides listed in the Virginia Tech Nursery Crops Pest Management Guide are thiamethoxam (Flagship 25WG at a rate of 6 oz./100 gallons of water) or dinotefuran (Safari SG ¼ to ½ lb. / 100 gallons of water). These systemic products are absorbed and dispersed throughout the plant. Only one application a year is necessary to target the larvae feeding within the leaf. In central Virginia, it is recommended that the application takes place late June through mid-October.

To be noted: While Saunders Genetics has worked with nursery growers who have successfully used the pesticides listed above, no guarantees or promises, nor any opinions concerning the effectiveness or safety of these or any other pesticides are made. Always read the labels and other product information from the manufacturer and discuss the proper use and application of products with appropriate company representatives or acknowledged experts.

Although chemical control is an option on susceptible cultivars, there are also many boxwood varieties that have shown genetic resistance to Boxwood Leafminer. This genetic resistance is a defining feature in the NewGen™ Boxwood program where the goal is to provide grower-friendly plants that can thrive when faced with pest and disease pressure. NewGen™ boxwood were chosen for the program because they are more resistant to Boxwood Leafminer than most varieties currently on the market. If you are replacing or planting boxwood, consider NewGen™ varieties so that costly and troublesome sprays will not be necessary.

Frost or Freeze Damage and How to Manage It

Straw-colored foliage is typical of spring frost injury.

This year, 2020, is already in the history books as the “Year of the Coronavirus,” but boxwood growers will also remember it for some of the worst frost/freeze damage seen in decades. Central Virginia experienced two abnormally late spring frosts, one in mid-April and the other on Mother’s Day morning, May 10. Although boxwood are typically hardy evergreens that can tolerate cold, they can be susceptible to injury when extreme weather events occur. There are two different types of cold temperature-related issues. Abnormally cold night temperatures in the fall or spring result in frost or freeze damage whereas extreme cold winter temperature events result in cold injury.

Frost or Freeze Damage

Running irrigation water over the plants during a cold event can minimize frost or freeze injury.

The terminology frost damage usually refers to a rather mild frosting of plants in the fall or spring, generally resulting in light die-back in the tops of boxwood. Freeze damage occurs at the same time but describes more severe damage as a result of colder temperatures or more prolonged cold temperatures. In the mid-Atlantic area of the United States, the damage from these weather events can occur in the fall from October through early November, or in the spring from late March through early May. The resulting damage is a “burning” of the most tender foliage, usually the tips of the newest growth, of the boxwood. The damage occurs when the temperature gets below 30 degrees Fahrenheit, with the worst damage occurring during a freeze event when the temperatures get into the low to mid 20’s. An extreme freeze event, with temperatures in the low 20’s in the fall or spring, can cause bark splitting, with resulting dead limbs of perhaps even the entire plant.

Frost blankets are specifically designed to be placed over plants during cold weather events. The fabric is breathable to prevent diseases, but warm enough to protect tender boxwood.

The discoloration and spotting on this Buxus microphylla cultivar could be mistaken for Boxwood Blight but is actually a common sign of frost or freeze damage.

In the fall, the extent of the damage of a frost/freeze event is related to the temperatures leading up to the cold temperatures, with the worst damage occurring with a very warm fall followed quickly by a severe and early frost or freeze.

In the Spring, the extent of the damage is related to the development of the new growth in the boxwood, with the worst damage occurring with a very early and warm spring fully pushing out the new growth of the boxwood, followed by an abnormally cold night.

A Time to Plant Boxwood

NewGen Freedom® mixing with some bright flowers in a perennial bed.

With many people hunkered down at home during the COVID-19 outbreak, everyone is finding ways to de-stress and pass the time while staying healthy. Most nurseries and garden centers remain open as essential businesses and provide many people a safe way to celebrate the season. Nurseries and garden retailers are adapting to ensure customer safety, all while providing the plants and supplies needed to create and maintain at home gardens and landscapes. Spring marks the perfect time to plant many varieties of trees and shrubs, including boxwood. Time to take a break from the news, or binge watching a new show, and spend some time soaking up Vitamin D in the garden!

Boxwood tolerate pruning well and can make beautiful, intricate hedges.

Boxwood offer many benefits to new and established landscapes and are known for their easy maintenance. With few pests and diseases affecting them, most varieties and cultivars require annual pruning and minimal supplemental nutrients. These timeless evergreen shrubs are characterized by their longevity, come in many sizes providing versatile shape and structure to any landscape for ages to come.

Boxwood lining a walkway to a front door.

Though boxwood require minimal care, there are a few things to consider before planting, beginning with site selection.

Start by checking the soil to be sure it provides good drainage. Boxwood, like many plants, don’t enjoy having “wet feet” or their roots are sitting in soil that is regularly saturated with water. Soil with good drainage provides an environment for healthy roots and overall plant growth. Boxwood prefer a soil pH that is more neutral, preferably between 6.5-7.0. If your soil pH is below that, amendments such as dolomitic lime or other fertilizers can be added to raise the pH.

When selecting a site for your boxwood, it is also important to consider sun exposure. Many boxwood prefer some shade, but different varieties and cultivars can handle different exposures. There are many varieties and cultivars of boxwood that offer different shapes, sizes, colors, and even pest and disease resistance! Now that you’ve found the perfect location, it is time to decide which cultivar fits your needs best. Resources such as the Saunders Brothers Boxwood Guide offer lots of information about many of the varieties on the market. There is also detailed information about NewGen Freedom® and NewGen Independece® under the NewGen™ tab on our website.

NewGen Independence® and it’s dark shiny foliage catching the last of the afternoon sun.

Once you’ve selected the proper location and best variety for your landscape, it’s time to plant! Start by digging a hole approximately twice as wide as the root ball, and deep enough that about 2” of the original root ball is above the soil line. This is often referred to as “planting high,” helping with drainage. Make sure the root ball is sitting on undisturbed soil, so that the soil won’t settle and reduce drainage later. See the diagram below.

After planting and covering the root ball, make sure to irrigate well. Many experienced gardeners will tell you the first watering after planting is the most critical! Be sure to fully soak the recently planted boxwood, being diligent that the water soaks all the way through the root ball. Afterwards, periodic watering on an as-needed basis is best. Monitor for adequate moisture, approximately 1” of precipitation or irrigation a week for the first year. For more detailed information about site selection and irrigation, check out the highlighted article.

Boxwood make great hedges around container and vegetable gardens.

Finally, once your new boxwood is planted and watered in, it is time to mulch. Mulching boxwood used to be discouraged, however new research findings have proven that mulching boxwood is an essential part of maintenance. Not only does mulching reduce weeds, regulate soil temperature, and encourage proper soil ecology, it also helps prevent Boxwood Blight. A layer of mulch about 1” thick is sufficient.

Although many may be feeling discouraged as we adapt to life at home for the next few weeks, it is important to look at this as an opportunity to start something new or revitalize an old landscape. Getting your hands dirty with some fresh soil as you add your beautiful new boxwood to your landscape is sure to bring a smile to your face and hope in your heart. Take this time to spruce up your green space with a landscape you will cherish for years to come.

Different cultivars of boxwood can be used together to make elegant designs.

For more garden inspiration, check out the Boxwood Photo Garden.

Tips on Pruning Boxwood

This tall boxwood with some winter color and shaggy branches before its annual pruning.

Pruning is an essential part of plant upkeep and an excellent method of preventative maintenance for both young or more established plants. Most ornamental plants benefit from annual pruning, and boxwood are no exception. There are many benefits both for the overall look and health of the plant, making it important to establish a pruning schedule for boxwood in any landscape.

One of the most common reasons to prune is to shape up boxwood and provide a cleaner more defined appearance. Boxwood are characterized by the structure they provide to gardens, and pruning helps to maintain a clean shape. Early spring, before boxwood begin to flush, is the best time of year to prune. Any old winter color, or tips that have been burned over the winter season, can be trimmed away and will disappear after the spring flush.

Not only is it important to prune, but proper pruning techniques are crucial to long-term success with boxwood and may differ slightly with each cultivar. It is important to choose the correct cultivar to avoid the need for excessive pruning. Before and during annual pruning, proper sanitation of necessary tools is important. Any tools should be properly cleaned with alcohol, bleach, Lysol® or some other disinfecting solution before and after working with boxwood to lessen the possibility of spreading disease.

Buxus ‘Dee Runk’ before annual pruning.

The same Buxus ‘Dee Runk’ after annual pruning.

As mentioned above, the best time to prune boxwood is in the late winter to early spring, before the plant breaks dormancy and begins flushing. This is typically late February to mid-March in central Virginia. Late winter/early spring pruning minimizes the time between pruning and new growth as well as stimulating a strong spring flush. Also, Boxwood Blight tends to be much less active in cold temperatures.

This freshly pruned boxwood had its winter color pruned off and is ready for its spring flush!

If you are looking for a more manicured look, some gardeners like to prune in late spring, after the spring flush to achieve a more formal shape. Mid-summer and early fall pruning stimulate late fall growth that may be burned by frost or early winter freezes. Waiting until early winter might not be detrimental; however, it leaves pruning scars on the leaves until the spring flush is initiated.

Cultivars that are more dwarf or have very tight habits benefit from annual thinning to open up the inside of the plant. Thinning is typically done by reaching into the plant and breaking or cutting out branches with hand pruners. These branches can be 6-10 inches long on larger cultivars, or only a couple of inches on a dwarf cultivar. This will leave pockets or holes in the plant for air and sunlight penetration. Using hand pruners will result in a cleaner cut and lessens the possibilities of disease introduction. Any cultivars that are sheared regularly will benefit from thinning to lessen disease susceptibility.

Larger and more vigorous cultivars are generally tolerant to shearing or more radical pruning techniques. Use loppers or shears to drastically reduce overall plant size on vigorous plants, taking care to leave one-half to two-thirds of the foliage undisturbed. This foliage will produce energy the plant needs to recover. The plant should develop new foliage along the bare stems. Full recovery may take several seasons. Plants that require more drastic pruning may need to be pruned over several years to reduce the overall size in steps and not jeopardize the plant’s health. To minimize radical pruning, do not select large cultivars for applications where small cultivars would be more suitable.

Large Pruning shears can be used for larger, more vigorous varieties.

Establishing pruning as part of the overall maintenance of your boxwood encourages healthy growth on both young and more established plants. Whether it is to neaten the plants appearance, rejuvenate an overgrown shrub, or help maintain a healthy environment, annual pruning is a key part of your success with boxwood.

Feb. 2020: Third International Summit on Boxwood Challenges

The NewGen™ and Saunders Brothers teams at the Third International Summit on Boxwood Challenges, hosted by the American Boxwood Society.

Last month the American Boxwood Society hosted its Third International Summit on Current Boxwood Challenges. Over 140 people heard from researchers and growers from Europe, Canada and the United States who discussed the latest research on Boxwood Blight and the Boxwood Tree Moth. This one-day event was hosted at the National Agricultural Library in Beltsville, Maryland.

Although the Boxwood Tree Moth has not been found in the United States, it has devastated boxwood production in Europe. The morning session of the event began with research on the biology of the moth, determining the invasive pathways that introduced the moth to Europe, concluding that the pest was originally introduced from eastern China to Germany in 2007 and has since spread significantly over Europe. Most of the spread has been from the transport of infected plant material, with some movement through native boxwood forests. The moth was found in the United Kingdom in 2008 and has since spread around the southern parts of the country. Chris Poole, the Chairman of the European Boxwood & Topiary Society, shared management strategies being utilized in the United Kingdom and around Europe against the moth.

The morning session finished with speakers from North America, focusing on what the Canadian industry is doing to monitor and prevent the spread, and how the U.S. can prepare against the moth. First identified in Ontario in October 2018, OMAFRA (similar to U.S. Extension) has diligently been monitoring and treating the pest as it appears. Using many of the same tactics that have been effective in Europe, most infections are low to moderate, with less than 10% considered severe. In the United States, using pheromone traps for detection and diligently spreading the word about this potentially invasive species can aid in catching the moth early. In the event that it is found, there are methods of control already available. Researchers are aware of the pest and are focusing efforts to learn from those already affected in order to prevent the introduction of Boxwood Tree Moth to the United States.

The afternoon focused on Boxwood Blight starting with a recap of what is known about the disease and ways to treat and prevent it. Mary Ann Hansen, who works in the Plant Disease Clinic at Virginia Tech, has many years’ experience identifying Boxwood Blight. She shared information about the biology of the disease, how to identify it, and how to clean it up in the event of an infection. There are many tools available to the public about Boxwood Blight, including the Virginia Boxwood Blight Task force website.

The event finished with several presentations on further research being done around the U.S. There are many projects in the works focused on learning new and effective control strategies. Projects range from breeding programs to biocontrol studies to thermotherapy, all being done at many universities around the U.S. There is still no silver bullet in preventing or treating Boxwood Blight, but the is a light at the end of the tunnel as much of the research proves positive. One of the recent studies showed a decrease of Boxwood Blight lesions by 97% just from adding a layer of mulch. You can read more about that study here. As research continues, we only get more positive that as an industry we can overcome this challenge.

If you’d like to learn more about events like these, check out the American Boxwood Society’s website.

Botany of the Boxwood Flower

By: Keith Yoder, Professor Emeritus of Plant Pathology, Virginia Tech

Boxwood flower buds.

Figure 1. Dormant boxwood flowers. Note terminal buds, right, and axillary buds, center left

Boxwood typically blooms in February and March in central Virginia. The dormant flowers appear generally globular (Figure 1), but are actually flower clusters composed of a single female (pistillate) flower tightly surrounded by as many as six male (staminate) flowers. They are arranged along shoots as axillary clusters or at the shoot tip as terminal clusters.

With warming temperatures in late winter, swelling buds signal the onset of flowering. The female flower has 4 to 7 or more sepals at its base and a single three-celled ovary topped with three short styles with two-lobed stigmas (Figure 2). The ovary has three locules, each with two ovules. Each ovule is capable of developing into a seed, potentially yielding six seeds per flower. The male flowers have four sepals arranged as two opposite pairs and four stamens, each opposing a sepal, composed of a thick filament topped by a two-celled anther.

Figure 2. Emerging pistils of female flowers.

Figure 3. Developing anthers of male flowers.

As the flowers develop in the spring, the tips of the three pistils begin to protrude from the central female flower bud (Figure 2), and they expand further into the two-lobed stigmas where the pollen is received. Meanwhile, yellowish-green anthers emerge from the male flowers (Figure 3). The initially plump two-celled anthers begin to split (dehisce) longitudinally and shed pollen (Figure 4), which is deposited on the exposed stigmas. The inconspicuous flowers lack petals and, when viewed from some distance, much of the observed color is due to the appearance of the anthers on a heavily-blooming plant.

Figure 4. Male flower anthers shedding pollen.

Figure 5. Developing fertilized female flower. (Male flowers had been removed to prevent self-pollination for controlled breeding purposes).

After pollination, the fertilized ovaries begin to expand and develop three distinct horns on the immature green capsules (Figure 5). After they mature in mid-summer, the capsules split longitudinally (Figure 6) and open suddenly to forcibly discharge the shiny black seeds (Figure 7).

Figure 6. Capsule from which seeds have been discharged.

Figure 7. Seed capsule with discharged seed.

The above descriptions of the flowers and flowering process are ‘typical’, but there are some exceptions in structure and development. For example, we have observed ‘National’ with only female flowers in the American Boxwood Society Memorial Garden, State Arboretum of Virginia, Blandy Experimental Farm, Boyce VA. The time of development may vary without explanation. After seeing flowers with anthers of an unidentified variety open in Winchester VA in early December 2019, we scouted the plantings at Blandy and found ‘Miss Jones’ and ’Tall Boy’ also with anthers exposed. One would not expect flowers pollinated in December to develop through mid-winter.

References:

Batdorf, L. R. 2004. Boxwood; an Illustrated Encyclopedia. The American Boxwood Society, Boyce VA. 343 pp.

Batdorf, L. R. 2005. Boxwood Handbook, A Practical Guide, 3rd Edition. The American Boxwood Society. Boyce VA. 123 pp.

These publications are available at:  https://boxwoodsociety.org/abs_publications.html

Dec. 2019: Boxwood Blight Update

A field of boxwood affected by Boxwood Blight.

Since its introduction to the United States in 2011, boxwood blight has been found in 26 states. Its affects have been seen from the Mid-Atlantic to the west coast in varying degrees. One of the biggest contributing factors to the prevalence and spread of this disease is climate. Boxwood blight requires specific environmental conditions which vary year to year. This fungal disease spreads by spores that move by water splashing, physical contact, or on debris. Infections occur during humid, warm periods, and can spread quickly when conditions are ideal.

The map above shows states with reported cases of Boxwood Blight by year.

Characteristic symptoms of Boxwood Bight include dark streaking on the branches, leaf spots, and defoliation.

As many growers recall, 2018 was a devastating year, especially in the Mid-Atlantic. With record breaking rainfall and extended periods of warm, wet weather, many growers, landscapers, and homeowners saw more cases of the disease than previous years. Mary Ann Hansen, who oversees the Virginia Tech Plant Disease Clinic reflects, “In 2018 when we had so much rain across the state, the VT Plant Disease Clinic received 188 boxwood samples that were positive for boxwood blight. This amounted to over 11% of our sample total.”

Bennett Saunders next to the Tye River at record high levels in September 2018 after another heavy rain storm.

In Piney River, VA we saw over 90 inches of rain throughout the year, compared to the annual average of about 45 inches. Reports of flooding and extended rain events throughout the spring, summer, and fall were followed by reports of infection.

Juxtaposed to the previous year, 2019 has been uncharacteristically dry, leading to fewer cases. Mary Ann from Virginia Tech reports, “In 2019, we only received 44 boxwood samples that were positive for boxwood blight, and this amounted to less than 3% of our total samples. The number of samples received by the Clinic doesn't necessarily represent the amount or severity of the disease across the state, but in this case, I think it probably did. The weather in 2018, especially in the fall, when boxwood blight tends to be a problem, was very conducive to boxwood blight, whereas the long drought and high temperatures in many areas of the state in 2019 were not conducive to boxwood blight. The fungal pathogen, Calonectria pseudonaviculata, does best at moderate temperatures with extended periods of leaf wetness.”

It is important to keep in mind the effect the environment can have on the spread of plant diseases. For more information on Boxwood Blight and how to prevent it, check out the Virginia Tech Boxwood Blight Task Force website or read more about it here.

Not Just Another Pretty Face: The Importance of Grower Friendliness

NewGen Independence® in the landscape.

When new plants enter the marketplace, the emphasis is often on their benefits to the landscape.  What is sometimes overlooked is how they perform for the grower.  It is, of course, important to emphasize the qualities that will attract homeowners, but just as crucial is the degree of ease in growing them.  When choosing plants for the NewGen™ program, we wanted plants that would be able to perform in a production environment as well as for the consumer.

NewGen Freedom® in the landscape.

In addition to their disease tolerance and pest resistance, both NewGen Independence and NewGen Freedom© are exceptional growers in both container and field settings.  These plants will impress any grower with their tenacity, uniformity and performance in propagation and production.

UNIFORMITY

NewGen Freedom®

NewGen Freedom®

NewGen Freedom®

NewGen Freedom®

NewGen Freedom®

NewGen Independence®

NewGen Independence®

NewGen Independence®

NewGen Independence®

NewGen Independence®

Uniformity is an important characteristic in production because it eases overall plant maintenance.  Whether for pruning, spacing, or water and fertilizer needs, having plants that grow uniformly can make general maintenance a breeze.  Early selections of both NewGen™ boxwood show outstanding uniformity.  At the Saunders Brothers nursery, we grow plants in both containers and in the field; there is impressive consistency across the board in both environments. [See examples above of plants in both field and container production.]

Tenacity: Pest and Disease Tolerance

Uniform and clean NewGen Freedom® in container production.

Tolerance to pests and disease were top priorities when we made selections for the NewGen™ program, especially in light of the threat of Boxwood Blight and Boxwood Leaf Miner.  However, it was also important that these plants could thrive in an environment where there are other diseases common to a growing setting.  Both selections have done well against  other diseases such as Phytophthora (common root rot) and Volutella.  In the pictures following, you can see where these plants continue to thrive even when grown next to plants subjected to the very same diseases and environmental conditions.

Spotless foliage of NewGen Independence®.

Shiny, clean foliage of NewGen Freedom®

Propagation

A traditional propagation house with mist running, creating a very warm, humid environment for the cuttings.

A full house of NewGen Freedom® liners.

Growers also need to consider ease of propagation.  There are many different methods of propagation but “cutting propagation” is one of the most common.  During the process of producing roots, plants are particularly vulnerable.  The warm, high humidity environment that promotes rooting is also conducive to higher disease exposure, and unrooted cuttings are fragile.  Both NewGen Freedom© and NewGen Independence© are stellar propagation performers!  They are quick to root and maintain a uniform growing habit, making them simpler to bring to maturity.

A few full flats of clean NewGen™ liners ready to be shipped!

NewGen™ aims to offer high quality plants that are easy to maintain and grow, both for growers and those who purchase the plants.  These boxwood combine Grower Friendliness and exceptional landscape appeal in plants that will perform beautifully for years to come.

Tips and Tricks for Growing Cleaner Plants

Creating a phytosanitary plan doesn’t have to be a daunting endeavor. There are many simple steps you can take to grow cleaner plants. Saunders Brothers has worked with many researchers and Extension agents to establish protocol to help prevent the introduction and spread of Boxwood Blight at their nurseries. Although this plan was designed with Boxwood Blight in mind, these practices will help growers produce cleaner, more successful plants.

Foot mats/baths:

Foot baths are located at every walkway leading to the Saunders Brothers office.

One of the first and easiest steps to take is the inclusion of foot mats/baths for sterilizing shoes of anyone entering a growing area. These can be placed in greenhouses, worker common areas, and near offices. Having foot baths as a first line of defense minimizes the introduction of new pathogens to your growing area. Saunders Brothers uses foot mats at the entrance to all of their office and worker areas. Saunders Brothers uses Zerotol® 2.0, but a 10% bleach solution is also effective.

Disposable pant/boot covers:

Crews in the field nursery wear disposable suits when they are working on larger plants.

Crews wear rubber boots that can be easily cleaned and disposable pants when moving between growing areas.

An example of plastic pant and boot covers in the field.

Disposable pants and boots serve as a physical barrier between one’s clothing and the plants they are working in. If there are any spores or pests on the clothing, it is less likely they will migrate to the plants. Saunders Brothers employees wear disposable, plastic pant and boot covers while working in boxwood houses. Boxwood Blight spores can stick to tools and clothing moving from location to location, so instead of worrying about having fresh clothes, disposable pant/boot covers are the perfect solution.

This is also a great tool for landscapers that may visit many sites in a day. Instead of having to change or sterilize clothing, wearing disposable pant and boot covers greatly reduces disease or pest movement from site to site.

Sterilizing tools/equipment:

Pruning crews as Saunders clean their tools with alcohol between each house.

Even large equipment like digging machines are cleaned with sterilant between fields.

Sterilizing tools and equipment is an easy, practical step to take towards growing cleaner plants. It is a good practice to carry around a spray bottle of isopropyl alcohol. Research shows that a 50% isopropyl alcohol solution is effective at killing most plant diseases. Alcohol spray can be used to clean any handheld tools such as pruners, shovels, or trimmers. Other options of sterilants are a 10% bleach solution or Lysol® spray. Many researchers also recommend hydrogen dioxide products such as Zerotol® 2.0. Make sure to always check labels before you use any products. Most of these products are very user-friendly and are labeled to clean tools, equipment, or even surfaces.

Dragging a hose through a bed of infected plants and then moving it through a healthy bed could spread diseases. Taking an extra minute to spray the hose down with a sterilant could avoid a bigger cleanup in the future.

Cleaning Stations/Sectioned growing areas:

Cleaning stations in the field nursery.

Cleaning station in the container nursery.

This tip takes a bit more planning than some of the other suggestions, but might have the biggest pay off if you ever run into a disease or pest problem. Saunders Brothers has set up both their field and container nurseries in sections. In the container nursery, boxwood are grown in specific locations separated by roadways. In the field nursery, areas are sectioned based on geography. Each section has a cleaning station that all employees must visit at they enter and exit. Cleaning stations are stocked with:

• Disposable pant/boot covers

• Trashcan

• Boot bath and brush

• 70% Isopropyl alcohol spray/liquid hand sanitizer.

• High pressure water hose (field)

Crews using a cleaning station to rinse off their shoes and equipment.

Upon entering and exiting the area each employee must:

Entering:

• wear rubber boots, easily washed boots, or disposable boot covers

• step in boot bath/wash boots

• put on disposable pant covers

Exiting:

• remove and trash disposable pant covers or spray pants

• step in boot bath/wash boots

• wash hands/ use hand sanitizer

• rinse off tools, then spray with alcohol

This is an example of the sectioned boxwood production areas are at the containers nursery at Saunders Brothers.

The perks of setting up these sectioned areas is that in the event of an infection, you can quarantine one area, and continue production from the other locations. Consequently, each time a person or a crew enters a new area, they are cleaning off any potential pests or diseases.

Establishing cleaner growing protocol doesn’t have to be a daunting task. Taking some steps early on in production can help set you and your plants up for success while combating common pests and diseases. Consider these tips and find what works for you.

Benefits of Mulching Boxwood

Boxwood in the landscape with a think layer of mulch.

Mulching is a common landscape practice that is used to suppress unwanted weeds, reduce evaporation from the soil, and encourage proper soil ecology and structure while being visually appealing. Recent research has also shed light that mulching can be an effective tool to aid in pest and disease management. Earlier this year, Virginia Tech published data from a two-year study showing that mulching can be a great tool to help prevent Boxwood Blight.

The experiment was set up in two locations, one being an old nursery in Low Gap, North Carolina and the other a residential landscape near Richmond, Virginia, both previously devastated by Boxwood Blight. This field trial consisted of both mulched and non-mulched treatments and was done for two years under normal environmental conditions. The goal of this study was to evaluate mulch as a physical barrier to prevent the soil inoculum from splashing onto healthy plants.

The fungal pathogen Boxwood Blight (Calonectria pseudonaviculata) produces heavy, sticky spores on diseased leaves that fall to the soil. There is no evidence to date of the pathogen attacking boxwood roots, so it was thought that providing a physical barrier of mulch would prevent the inoculum from splashing onto the leaves where the pathogen can affect the plant. The experiment used containerized ‘Justin Brouwers’ boxwood which are known to be highly susceptible to Boxwood Blight, that were rotated through mulched and non-mulched plots at 1-to-2-week intervals.

A freshly mulched bed of NewGen Independence® and perennials.

Results of the experiment showed clear distinction between the mulched and non-mulched plants. The mulching reduced the number of Boxwood Blight lesions by up to 97%! Even the scientists working on the project were amazed by the unbelievable difference that mulch made. Although for a long time it was thought that mulching boxwood plants was a bad idea but, this study shows that it can be an exceptionally effective tool for Blight control. Below you will find a downloadable PDF of these findings. Saunders Brothers Nursery worked with Chuan Hong and his team to provide plant material for the experiment.

Boxwood blight is a multi-faceted disease that can be overcome with smarter growing practices and understanding. Mulching has been proven to be another very simple and accessible tool that can help prevent this disease.

Boxwood Site Selection and Irrigation

Boxwood being used as a hedge in a landscape.

Boxwood are known for low maintenance and longevity in a landscape, but in order to ensure such timelessness, it is important to select the best site for the plant. When properly planted and cared for, boxwood are easy to maintain. Paying extra attention at planting will ensure a flourishing plant for years to come.

In choosing the proper site, we recommend the following:

Several boxwood in a shady site.

• Choose the best cultivar based on size, shape, growth rate, maintenance, and exposure.

• Take a soil sample and have it tested. Look for areas of good drainage with a pH in the range of 6.5-7.0.

• Prepare a proper hole, making sure to plant the boxwood “high” with 2 inches of the root ball above the soil line. Be sure that water drains away from the plant and does not puddle near the root ball.

• Water thoroughly at the time of planting and maintain adequate but not excessive irrigation through the first couple of years.

Once the boxwood is properly planted, it is very important to water it. A thorough soaking at the time of planting is essential. This will probably be the most important watering this plant will ever have. Make sure to fully soak the root zone.

Boxwood being irrigated first thing in the morning.

Once this initial watering is complete, periodic watering should take place as needed. Allowing the root zone to dry between irrigation events will encourage root growth. We recommend approximately 1 inch of precipitation or irrigation per week for the first 1-2 years. Pay close attention during the hot and dry summer months, so that the boxwood does not stress. It is also important to pay attention that the plants have adequate moisture as winter approaches. In the Mid-Atlantic region of the United States, boxwood will continue to grow roots in the winter when the temperatures are still mild.

The arrows show holes on the drip tape where the irrigation water escapes.

Here the drip tape sits on top of a bed of field plants.

Drip irrigation is the ideal method for watering boxwood. Simple drip systems can be installed under the mulch and will offer thorough irrigation without wetting the foliage. In a drip system, water seeps from the drip tape without splashing. It enters the ground without puddling and conserves water. The rate of water from drip tape is very low, maybe a quarter of an inch per hour per emitter. Fungal diseases such as Boxwood Blight can be spread through water splashing that may occur with sprinkler methods of irrigation. If drip irrigation is not an option, make sure overhead watering takes place in the early morning, giving the leaves ample time to dry. It is important to never water boxwood in the late afternoon or evening because wet foliage through the night can lead to diseases and stress on the plant.

Raised beds ready for boxwood planting. It is very important that boxwood are planted “high” to avoid water pooling around the roots.

In 2018, Central Virginia had an annual rainfall of close to 90 inches, about double the normal amount. Boxwood throughout the region showed signs of stress, particularly those plants that were constantly in standing water. Whenever you plant boxwood, envision what the immediate landscape will look like after 3 inches of rain, and plant the boxwood in such a way that ensures water never puddles around the roots.

Giving added care before planting, boxwood are destined to succeed and maintain a timeless elegance in your garden.