Boxwood Blight found in Connecticut

claireplymouth z6b coastal MADecember 9, 2011

"In October 2011, boxwood blight (Cylindrocladium pseudonaviculatum) was positively identified in Connecticut. This is the first confirmed incidence of boxwood blight in the United States. According to USDA APHIS, the disease was almost simultaneously identified in North Carolina and Virginia as well.

This disease has not yet been found in Massachusetts, but the Massachusetts Department of Agricultural Resources is conducting a nursery survey.

For information on this emerging issue, refer to the following fact sheet provided by the Connecticut Agricultural Experiment Station:"

Boxwood Blight - A New Disease for Connecticut and the U.S.

Boxwood Blight found in Connecticut


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Thanks, Claire. I spent some time googling this but since I'm on an old laptop that's seriously challenged in the apps departments, I didn't find anything I could read (all pdfs) about this disease.

Do you know how severe it is? A killer, or just a nuisance?
- DtD

    Bookmark   December 12, 2011 at 11:11AM
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claireplymouth z6b coastal MA

DtD: All I know is what I read in that pdf I linked to. It sounds like it may be a killer, depending on wet weather.

I just copied a few excerpts from that pdf to give you a feeling for the issue.

"MANAGEMENT STRATEGIES: Whether in the nursery, garden center, or landscape, management of boxwood blight requires aggressive measures that include combined use of culture, scouting, sanitation, and when appropriate, fungicide sprays. Boxwood blight is generally considered a serious disease affecting the quality and aesthetics of plants, although in many cases it can lead to plant death. Since this disease has only recently been found in the U.S., we are not certain of any long-term implications on plant health, especially with regard to the role that repeated, defoliation might have on weakening plants and predisposing them to winter injury, insects, and opportunistic pathogens."

Cylindrocladium pseudonaviculatum infects all aboveground portions of boxwood, but does not appear to infect the roots (Figure 1). Initial symptoms appear as dark or light brown spots or lesions on the leaves (Figure 2). These lesions often have dark borders. Spots enlarge and then coalesce, often with a concentric pattern or a zonate appearance (Figure 3). Infected leaves then turn brown or straw colored, so infected plants look "blighted" (Figure 1). Defoliation often occurs very quickly after foliar symptoms first develop.

The fungus also infects the stems, which results in distinctive and diagnostic dark brown to black lesions, sometimes with an angular, diamond-like pattern (Figure 4). Many black lesions can be found along a stem, from the soil line to the shoot tips (Figure 5). Heavily infected plants drop most of their leaves. Although the plant attempts to regrow, repeated infection and defoliation can weaken the root system and lead to plant death, especially for young plants or new transplants.

Boxwood blight can spread very rapidly under warm and humid conditions. For example, in 2011 we have seen several examples of established boxwood plantings in Connecticut landscapes that were apparently killed in one season following the introduction of infected plants�2011 was a particularly cool, wet year that included several violent rain events (Figures 6 and 7)."


Boxwood blight has been reported to occur on all Buxus species to date, although some species and cultivars appear to be more susceptible than others. Buxus sempervirens �Suffruticosa� (English boxwood) and B. sempervirens (American or common boxwood) appear to be highly susceptible. Other species of boxwood grown in Connecticut that have been found to be infected include many cultivars of Buxus sinica var. insularis (Korean boxwood), Buxus microphylla (little leaf boxwood), Buxus microphylla var. japonica (Japanese boxwood), and Buxus sinica var. insularis X B. sempervirens hybrids (Table 1). Experimental inoculations have revealed that Sarcococca, another member of the boxwood family (Buxaceae), is also susceptible. The complete host range of this pathogen is not known. However, published reports have not shown evidence of substantial resistance, since no boxwood species challenged with C. pseudonaviculatum have demonstrated any immunity."


"Reports on fungicide efficacy from countries that have been dealing with this disease for many years are not encouraging, since fungicides have not been found to be particularly effective."

1 Like    Bookmark   December 12, 2011 at 5:36PM
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corunum z6 CT(6)

Good of you to post this, Claire. Had read the links under your post then this morning, via email, I received a letter from a local nursery with the below link attached. I have Green Mountain and Green Velvet which thus far, appear healthy. Sincerely hope this does not become a devastating blight. The Halloween Arborgeddon was bad enough.


Here is a link that might be useful: Fox, CT News, Boxwood Blight

    Bookmark   December 14, 2011 at 7:50AM
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claireplymouth z6b coastal MA

Thanks for the new link, Jane. This really sounds like a serious disease and gardeners should keep a close eye on their boxwoods.

I have a very big old, inherited, no-id boxwood, two little Vardar Valleys and two little Rochesters, and I really don't want to lose any of them.


    Bookmark   December 14, 2011 at 10:07AM
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diggerdee zone 6 CT

Thanks, Claire. I read your links, then saw two or three articles locally, including one in this morning's paper. Hoping that this doesn't become widespread.


    Bookmark   December 14, 2011 at 2:14PM
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ctlady_gw(z6 CT)

Wow... I only have a few boxwoods, but will keep an eye on them!

I think this important ID by CT Ag Station scientists is just one more reason the residents of CT need to make their voices heard LOUD and STRONG next time the state suggests cutting that institution or its incredible staff. They are worth their weight in GOLD and we're lucky to have them!

    Bookmark   January 1, 2012 at 10:51PM
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claireplymouth z6b coastal MA

I just got an email from the UMass Extension:


In December 2011, the UMass Extension Plant Diagnostic Lab working with samples collected by MA Dept. of Agricultural Resources (MDAR) inspectors positively identified boxwood blight (Cylindrocladium pseudonaviculatum) in Massachusetts. Beginning in early December, MDAR inspectors performed trace forward surveys of nurseries and garden centers identified by USDA APHIS PPQ as having received boxwood plants from nurseries in CT known to have some boxwood blight infected plants.

In the mid-1990?s, plant pathologists in the United Kingdom first identified the fungal disease. By 2002, boxwood blight was present in New Zealand. How the fungus arrived in the United States is unclear, but within the last year, it has turned up in Virginia, North Carolina, and Connecticut landscapes, garden centers, and nurseries.

The most susceptible species appear to be English (Buxus sempervirens 'Suffruticosa') and American or common boxwood (B. sempervirens), although many species of boxwood are susceptible to infection. Asymptomatic but infected plants of resistant varieties can introduce this pathogen to uninfected areas. The fungus colonizes all aboveground portions of the plant. Initial symptoms appear as dark or light brown circular leaf spots. Infected leaves then turn brown-tan, which is rapidly followed by defoliation. In addition, black lesions often develop on twigs and stems. Plants are not killed by this disease, but become so defoliated as to be aesthetically unacceptable. Infected plants introduced into older, well-established plantings will rapidly spread the disease to healthy plants.

This disease is spread primarily by water (rain splash, irrigation, runoff, etc.) and by the movement of plant material in the trade. The best management strategy at this point, before more is known about this pathogen, is to not introduce any boxwood from unverified sources, either into the nursery or landscape. For more information about this emerging issue, go to UMass Extension Landscape, Nursery, and Urban Forestry web site at for a fact sheet with a detailed description of boxwood blight and its management.

Ellen Weeks
UMass Extension Landscape, Nursery and Urban Forestry Program
French Hall
230 Stockbridge Rd.
Amherst, MA 01003
(413) 545-0895
Fax. (413) 577-1620

    Bookmark   January 6, 2012 at 10:42AM
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