The genus Buxus (commonly referred to as boxwood in North America or box in Europe and other areas of the world) is prized for its use as individual specimen plants, hedges, parterres, and landscape groupings.
Due to high resiliency under heavy pruning, boxwood plants are frequently grown as topiary or bonsai.
Most boxwood species are tropical with the most diversity found in Cuba, China, and Madagascar,
but native species are also located in additional areas of southern and eastern Asia, the Caribbean, Central America, Mexico, northern South America, western and southern Europe, and Africa.
Only the European and some Asian species can survive in temperate climates (von Balathazar, et al., 2000).
In general, boxwood suffers from few pests or diseases, which is one reason the recent introduction of boxwood blight disease to Europe and North America has been so significant to people who grow boxwood.
The U.S. addressed this devastating disease by fostering an unprecedented level of collaboration among scientists, growers, regulators, and the crop protection industry.
AmericanHort and IR-4 facilitated the formation of a research team comprised of government and university researchers to study key factors in disease development and mitigation under U.S. conditions.
The U.S. research team is collaborating with European and New Zealand scientists, where this disease has been present for a number of years.
How to Revive a Buxus Plants
If you find large branches of your mature Buxus Plant turn orange or tan, the plant is probably struggling with Buxus decline.
What’s this? Buxus decline in bushes is a condition caused by fungal diseases and plant stress.
Continue reading to find out about Buxus’ decline symptoms and suggestions for controlling decay.
What’s Buxus Decline?
If your Buxus bushes experience stress conditions – like improper pruning, poor drainage, or perhaps cold injury – they might contract syndrome known as a boxwood decline.
This disease can discolor and harm your mature plants. It may be caused by the fungus Macrophoma, which probably causes the oldest foliage to turn yellow.
In check carefully, you will notice little black dots on the old leaves. These’re the fruiting structures.
Buxus decline in shrubs may also be a consequence of the fungus Volutella.
It creates orange, pink fruiting specks on Buxus branches if the weather conditions are warm and wet. Buxus decline attacks more mature Buxus, twenty years old or more.
It generally happens after the plant has experienced some anxiety, like winter damage, extra water, or bad pruning in the ground.
When you look for Buxus decline symptoms, be on the lookout for discolored stems and vegetation. The stem discoloration could be constant, but it is not always.
Sections of the vegetation of infected Buxus will switch light green. In time, the foliage turns yellow and then fades to tan.
How to Revive a Buxus Plant
Be sure watering is done regularly, and at the same time, make sure that roots have good drainage.
Stay away from situations that stress the crops. Make sure excessive mulch is not layered over the root zone.
If development occurs nearby, be careful that the Buxus roots aren’t injured or the soil compacted.
Keep the Buxus free from insect infestation. Among the causes of dieback diseases such as Buxus decline is crowded development within the branch crotches.
If you see discolored or perhaps withered leaves, get rid of them by gently shaking the crops and then selecting the old foliage.
Prune away dead and dying limbs that also thin out the middle of the plant.
What is Boxwood Blight?
Boxwood blight symptoms and epidemiology
Boxwood blight is generally first noticed on the plant in late spring or early summer when a section of a plant becomes chlorotic or brown and affected foliage falls from the plant,
leaving bare branches.
Similar symptoms are often seen on stressed boxwoods planted in locations with poor soil or cold exposure and often suffering from boxwood decline (a syndrome associated with nematodes and poor environment) or Volutella blight (caused by Volutella buxi) (Douglas,
However, C.ps. can attack otherwise healthy plants, and the dead leaves tend to fall off rapidly.
Close inspection of the leaves of boxwood infected by C.ps. show round dark lesions which grow larger and coalesce.
In humid conditions, the underside of the leaf will have a white frosty appearance caused by the formation of upright bundles of fungal spores.
On stems, lesions are dark and elongated; this is considered a diagnostic symptom of boxwood blight since other fungal pathogens causing lesions on leaves do not produce elongate lesions on the stem (Douglas, 2012).
The disease can kill plants, especially young boxwood plants (Henricot, 2006), but older boxwood will often produce new leaves and recover.
Repeated infections will weaken the plant, however, and it may lose its suitability as a formal hedge or topiary due to branch loss.
It is not yet clear whether differences in climate will make the disease in the U.S. more or less serious than it is in Europe.
The disease may be introduced into a site on diseased stock, by animals (birds, deer, or people) infested with spores, or by use of infested tools (Henricot, 2006).
Once a plant is infected, diseased leaves and twigs produce copious numbers of sticky spores that are then spread, primarily by water splash over
short distances or on infested objects (Douglas, 2012; Henricot, 2006).
Inside infected leaves and twigs, small clumps of thick-walled fungal cells (called microsclerotia) are formed (Weeda, et al., 2012).
These clumps remain in plant tissue and fall to the ground in diseased leaves. When mixed with soil under laboratory conditions, they have been shown to infect plant tissue that comes in contact with the moist soil (Dart, et al., 2013).
In decomposing infected leaves left on the surface of topsoil or buried at a depth of 5 cm, C.ps. survives and sporulates for at least 5 years (Henricot, et al., 2008).
Besides boxwood, Sarcococca (sweet box), Pachysandra terminalis (Japanese spurge) (LaMondia et al., 2012), and P. procumbens (Allegheny spurge) (LaMondia & Li, 2013) are known to become infected.
Infected Pachysandra terminalis have been found associated with infected boxwood in the landscape (Douglas, 2012), but the importance of this to disease spread is unknown.
Boxwood blight is most serious in warm, humid weather (18–25°C) and the complete life cycle can occur in 7 days (Henricot, 2006). Excessively hot temperatures, however, (>30°C) will kill the pathogen in host tissue (Shishkoff, unpublished data).
What are the symptoms of box blight?
Both of these disease-inducing fungi display easy to spot symptoms.
It’s prudent to check out the plants regularly and handle some affected areas as soon as possible as box blight gets increasingly hard to cope with as time goes by.
So, what does box blight look like?
The symptoms depend on which fungus your plants are infected with.
Cylindrocladium buxicola – in the first phases of the illness, the plant life has patchy areas of brown color, withered leaves, and, as it progresses, the impacted areas will lose the leaves.
Some other infection symptoms to consider are black striped, or perhaps whole blackened stems, and a slender grey fungus on the foliage.
What are some ways to deal with box blight?
Box blight hedge therapy is a long-lasting and challenging task, but dedication and patience could be done.
If the condition is too widespread, it could be better to ruin the infected plant and grow a proper replacement instead.
Before we get going, you must consider steps when healing box blight to minimize the risks of the disease spreading.
- Clean the tools when you’re done using them. You can make use of diluted household bleach or perhaps methylated spirits.
- Wash the clothes you had been using when taking on the infection.
- Remove any soil or leaves from the bottoms of the shoes of yours.
Now we are ready; let us move on to the box blight cure.
Step one. Regain back control.
Since Buxus blight attacks the foliage and stems of plant life, the first process is removing the infected areas to prevent the illness from spreading.
It would be best if you accomplished this during a dry time. If you prune the infected areas as the plant is damp or perhaps there’s rain forecast, the illness will spread rapidly.
Knowing how much of a vegetable to get rid of can be tricky in many circumstances, but you will find three straightforward options with Box Blight.
Which option you choose is dependent on the seriousness of the infection.
For a lot easier clean-up later, put a transparent plastic sheet around the bottom part of your saving vegetable.
If you’ve noticed the infection during the first stages, this’s the choice for you. Just cut the infected stems back again until they’re brown on the outside and vivid eco-friendly beneath the bark. When you reach the healthy areas of the plant, cut it around a bit more.
When faced with a large-scale infection, the perfect strategy is usually to lessen the vegetable’s height by half, or perhaps until you will find no stems with black spots.
If the infestation is too severe and you do not wish to change the plant, the one choice is to cut the whole plant down until it’s only a stump.
No matter which option you pick, when you are done with pruning, it’s a wise idea to spray the rest of the vegetable with a fungicide to get rid of the lingering spores.
Additionally, there are box blight commercial treatments out there. These specialized fungicides are ideal if the impacted areas are way too small to prune.
How to Revive a Buxus Plant and how to prevent the infection is always a challenging task.
For the optimal revival, you must notice infection as early as possible.
Be sure not to transfer spore to another healthy Buxus Plant. This would ruin all the good work.