By David Coyle, Ph.D.
Boxwood, whereas not native to North America, is a standard evergreen panorama plant on this continent. It has proven no indicators of turning into invasive regardless of being planted in landscapes as early as 1653! This plant is extraordinarily frequent all through the U.S. and lots of boxwood (Buxus) species and cultivars are used to supply a contact of inexperienced in city, suburban, and rural managed landscapes. Sadly, boxwood is vulnerable to many alternative pests, and administration of those pests is essential to sustaining a wholesome panorama.
A new article revealed final week within the open-access Journal of Built-in Pest Administration outlines a number of completely different arthropod pests and pathogens that may impression boxwood in panorama settings. I spoke with two of the authors—Karla Addesso, Ph.D., and Fulya Baysal-Gurel, Ph.D., of Tennessee State College—about what these pests imply for boxwood cultivation within the U.S.
Coyle: It appears to me boxwood is so ubiquitous and generally planted, particularly in new developments, that I’m guessing many people probably don’t even know they’ve boxwood on their property. Is boxwood a type of “invisible however all over the place” vegetation, or do you assume most individuals have a greater thought of what it’s and the place it’s on the panorama?
Addesso: I additionally lean towards seeing boxwood as a type of “background” species which can be so frequent they turn out to be invisible. They’re additionally simply confused with sure holly shrubs (e.g., Ilex crenata), that are generally substituted for boxwood within the panorama. As a result of this plant is so ubiquitous, it’s a main income generator for the nursery trade.
Baysal-Gurel: Boxwood is the no. 1 evergreen shrub bought within the U.S., valued at $126 million wholesale, and is an iconic species within the American panorama, particularly in boxwood gardens.
Coyle: That is probably why they’re so typically unnoticed—they’re all over the place! Of the pests you spotlight in your paper, which do you assume has probably the most potential to trigger injury, and which one really does trigger probably the most injury?
Addesso: From the insect aspect, the field tree moth Cydalima perspectalis is probably the most devastating pest, notably if populations utterly defoliate the plant. After all of the leaves are consumed, caterpillars will feed on bark. Repeated injury to the stem tissue can kill vegetation, as noticed in wild stands of boxwood in Europe. When it comes to pathogens, boxwood blight is definitely unfold and also will wipe out complete stands of boxwood. In a contest between these two pests, boxwood blight is the tougher administration concern, as a result of as soon as it’s in a planting it may be tough to eradicate. The caterpillars, in distinction, may be managed with pesticides if detected earlier than an excessive amount of injury happens.
The field tree moth Cydalima perspectalis is probably the most devastating insect pest of boxwood, notably if populations utterly defoliate the plant. (Vital defoliation proven right here.) After all of the leaves are consumed, caterpillars will feed on bark. Repeated injury to the stem tissue can kill vegetation. (Picture by Ferenc Lakatos, College of Sopron, Bugwood.org)
Coyle: Are some pests are extra frequent (or extra of a problem) in sure areas of the U.S.?
Addesso: Field tree moth is new to North America, so whereas it’s more likely to turn out to be extra widespread in time, its impression is presently restricted to the northern border of New York state and Ontario, Canada. The opposite boxwood pests are widespread wherever boxwood is discovered.
Coyle: For folk that don’t wish to use pesticides, what are a number of the greatest methods to handle insect or fungal pests on boxwood?
Addesso: As with most points, prevention may be key. Householders and landscapers can scale back the chance of illness introduction into the panorama by rigorously inspecting vegetation previous to transplant. Offering boxwood with optimum rising circumstances may also scale back pest and illness strain. This contains correct pruning, fertilization, and irrigation when wanted. If conventional chemical controls should not an choice, some boxwood points may be managed by pruning out infested sections or utilizing horticultural soaps, oils, or microbial merchandise.
Coyle: What are some scientific or administration advances that may actually assist the horticultural trade by way of boxwood pest administration?
Addesso: The best instrument for boxwood pest administration would be the breeding of resistant cultivars. Breeding packages for boxwood blight resistance also needs to display screen for resistance to different key illnesses and arthropod pests. A extra full image of boxwood cultivar resistance and susceptibility would enable growers and shoppers to make knowledgeable selections about which vegetation will carry out greatest of their area.
Coyle: Do you foresee a rise in boxwood pests because of local weather change?
Addesso: If adjustments in local weather alter the optimum vary for boxwood vegetation, it may improve plant stress in these marginal areas, making them extra vulnerable to pests and illness. Equally, if some pests, such because the boxwood mite Eurytetranychus buxi, can full extra generations resulting from a hotter local weather, this may additionally result in better injury in areas the place the mite was beforehand unproblematic.
So, sure, there are challenges to having that good boxwood plant or hedge or topiary—however all just isn’t misplaced! Efficient administration methods exist for many boxwood pests. In circumstances the place we don’t but have good suggestions or the place new pests are on the horizon, threatening to impression U.S. boxwoods, relaxation assured there are pest administration specialists and researchers working laborious to give you efficient options.
David Coyle, Ph.D., is an assistant professor within the Division of Forestry and Environmental Conservation at Clemson College. Twitter/Instagram/TikTok: @drdavecoyle. Electronic mail: email@example.com.