boxwood blight- a new threat to boxwood in the u.s. · pdf fileboxwood blight- a new threat to...
TRANSCRIPT
![Page 1: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/1.jpg)
www.ct.gov/caes
Boxwood Blight- A New Threat to
Boxwood in the U.S.
Sharon M. Douglas The Connecticut Agricultural Experiment Station
New Haven, CT
![Page 2: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/2.jpg)
Boxwood Blight in Connecticut
In October 2011, samples of boxwood with
unusual symptoms were submitted to The
Connecticut Agricultural Experiment Station
(CAES) for diagnosis.
Symptoms included leaf spots and blights,
rapid defoliation, distinctive black cankers
on stems, and severe dieback.
www.ct.gov/caes
![Page 3: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/3.jpg)
Chronology 6 October 2011
– CAES received an email inquiry from an arborist
with photos of boxwood with unusual symptoms
(Fairfield County).
– Requested sample of symptomatic plants.
11 October 2011
– CAES received boxwood samples.
– Tentatively diagnosed a new disease called
boxwood blight.
– Sample had been mailed, so stems and leaves
were contaminated with soil.
– Requested another sample. www.ct.gov/caes
![Page 4: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/4.jpg)
Chronology (cont’d)
17 October 2011
– CAES received another sample of boxwood
from a 7-year-old boxwood planting
(Middlesex County) with symptoms similar to
those exhibited in the first sample.
– Tentatively diagnosed boxwood blight.
– Sample was mailed, so stems and leaves
were also contaminated with soil.
24 October 2011
– CAES staff visited property to obtain an official
sample for confirmation.
www.ct.gov/caes
![Page 5: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/5.jpg)
Boxwood Blight Sample from Residential
Property in Middlesex County.
www.ct.gov/caes
![Page 6: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/6.jpg)
Boxwood Blight in Connecticut
(cont’d)
CAES tentatively identified this new disease
as boxwood blight, caused by the fungus
Cylindrocladium pseudonaviculatum.
– Had never been reported in U.S. or CT.
Sent samples to national mycologists at
USDA-APHIS-PPQ (Beltsville, MD) who
confirmed the fungus as C.
pseudonaviculatum (26 October 2011).
www.ct.gov/caes
![Page 7: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/7.jpg)
Boxwood Blight Timeline in U.S. Date* Location
10/24/2011 Surry County, North Carolina
10/26/2011 Middlesex County, Connecticut
10/31/2011 Carroll County, Virginia
12/13/2011 Providence County, Rhode Island
12/14/2011 Prince Georges County, Maryland
12/19/2011 Barnstable County, Massachusetts
12/20/2011 Washington County, Oregon
12/23/2011 Westchester County, New York
01/23/2012 Lancaster County, Pennsylvania
www.ct.gov/caes
* Confirmed by national mycologist, USDA-APHIS
![Page 8: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/8.jpg)
Boxwood Blight in CT
Confirmed in residential landscapes,
garden centers, and nurseries in the
following 5 counties:
– Fairfield
– Hartford
– Middlesex
– New London
– Windham
www.ct.gov/caes
![Page 9: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/9.jpg)
Boxwood Blight in New England National Agricultural Pest Information System (NAPIS)
www.ct.gov/caes
http://pest.ceris.purdue.edu
![Page 10: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/10.jpg)
Boxwood Blight
First described in the United Kingdom (UK)
in the mid-1990s.
In 2002, boxwood blight was found in New
Zealand.
– The causal agent was described and formally
named as a new species, Cylindrocladium
pseudonaviculatum.
Later in 2002, the boxwood fungus from the
UK was named Cylindrocladium buxicola.
– They are now known to be synonyms for the
same fungus. www.ct.gov/caes
![Page 11: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/11.jpg)
Boxwood Blight Causal Agent
Cylindrocladium pseudonaviculatum
=
Cylindrocladium buxicola
www.ct.gov/caes
![Page 12: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/12.jpg)
Boxwood Blight (cont’d)
Boxwood blight has been reported
throughout Europe.
– Belgium, Croatia, France, Georgia, Germany,
Ireland, Italy, the Netherlands, Slovenia, Spain,
Switzerland.
– Not present in Austria.
• Have an aggressive policy to immediately destroy all
infected Buxus spp. every time boxwood blight is
detected.
– New outbreaks continue to be reported.
www.ct.gov/caes
![Page 13: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/13.jpg)
Origin of the Boxwood Blight
Fungus
Geographic origin of the boxwood blight
fungus is not known.
It is NOT known how or when the
pathogen was introduced into the U.S.
www.ct.gov/caes
![Page 14: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/14.jpg)
Hosts
Boxwood blight has been reported to
occur on all Buxus species (natural and
laboratory infections).
– Some species and cultivars appear to be
more susceptible than others.
– Possibly as a result of physical traits.
For example:
– Buxus sempervirens ‘Suffruticosa’ (English
boxwood) and B. sempervirens (American or
common boxwood) appear to be highly
susceptible.
www.ct.gov/caes
![Page 15: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/15.jpg)
List of Hosts in Connecticut
Buxus sempervirens (Common
boxwood)
– ‘Suffruticosa’
– ‘Elegantissima’
– ‘Artic Emerald’
– ‘Jade Pillar’
– 'Graham Blandy'
Buxus microphylla (Littleleaf
boxwood)
– ‘Golden Dream’
www.ct.gov/caes
![Page 16: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/16.jpg)
List of Hosts in Connecticut
(cont’d)
Buxus microphylla var. japonica
(Japanese boxwood)
– ‘North Star’
– ‘Green Beauty’
– ‘Baby Gem’
www.ct.gov/caes
![Page 17: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/17.jpg)
List of Hosts in Connecticut
(cont’d)
Buxus sinica var. insularis (Korean
boxwood)
– ‘Winter Gem’
– ‘Winter Green’
– ‘Tide Hill’
– ‘Uptight’
www.ct.gov/caes
![Page 18: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/18.jpg)
List of Hosts in Connecticut
(cont’d)
Buxus sinica var. insularis X B.
sempervirens hybrid
– ‘Green Mountain’
– ‘Green Gem’
– ‘Green Velvet’
– ‘Chicagoland’
– ‘Green Ice’
– ‘Big Leaf Gordo’
www.ct.gov/caes
![Page 19: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/19.jpg)
Known Hosts- Europe and UK
Buxus balearica
B. bodinieri
B. glomerata
B. harlandii
B. microphylla
B. macowanii
B. riparia
B. sinica
B. sempervirens
Sarcococca spp.
www.ct.gov/caes
![Page 20: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/20.jpg)
Symptoms
Initial symptoms appear as light or dark
brown spots or lesions on the leaves.
Spots enlarge and then coalesce, often with
a concentric pattern or a zonate
appearance.
Infected leaves turn brown or straw colored,
so infected plants look “blighted.”
Defoliation occurs very quickly after foliar
symptoms first develop.
www.ct.gov/caes
![Page 21: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/21.jpg)
Leaf Spots
www.ct.gov/caes
![Page 22: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/22.jpg)
Leaf Spots
www.ct.gov/caes
![Page 23: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/23.jpg)
Leaf Spots
www.ct.gov/caes
![Page 24: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/24.jpg)
Leaf lesions with zonate patterns.
www.ct.gov/caes
![Page 25: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/25.jpg)
www.ct.gov/caes
Leaf lesions with zonate patterns.
![Page 26: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/26.jpg)
Symptoms (cont’d)
The fungus also infects the stems, which
results in distinctive and diagnostic dark
brown to black streaks or lesions,
sometimes with an angular, diamond-like
pattern.
Many black lesions can be found along a
stem, from the soil line to the shoot tips.
Infects all aboveground portions of
boxwood, but does not appear to infect the
roots.
www.ct.gov/caes
![Page 27: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/27.jpg)
Distinctive black stem cankers.
www.ct.gov/caes
![Page 28: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/28.jpg)
Black stem lesions.
www.ct.gov/caes
![Page 29: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/29.jpg)
Black stem cankers and lesions.
www.ct.gov/caes
![Page 30: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/30.jpg)
Blighted appearance from leaf and
stem symptoms.
www.ct.gov/caes
![Page 31: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/31.jpg)
Blighted leaves, defoliation, and stem
lesions.
www.ct.gov/caes
![Page 32: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/32.jpg)
Cankers and defoliation.
www.ct.gov/caes
![Page 33: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/33.jpg)
Symptomatic plants in holding
yard.
www.ct.gov/caes
![Page 34: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/34.jpg)
Symptomatic plants in sales yard.
www.ct.gov/caes
![Page 35: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/35.jpg)
Field-grown plants with symptoms and
leaf debris.
www.ct.gov/caes
![Page 36: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/36.jpg)
Symptoms and leaf debris.
www.ct.gov/caes
![Page 37: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/37.jpg)
Infected field-grown boxwood in
North Carolina.
www.ct.gov/caes Photo courtesy of Kelly Ivors, NC State
![Page 38: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/38.jpg)
Symptoms in potted plants.
www.ct.gov/caes
![Page 39: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/39.jpg)
Infected potted plants in NC nursery.
www.ct.gov/caes Photos courtesy of Kelly Ivors, NC State
![Page 40: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/40.jpg)
www.ct.gov/caes
Excessive leaf debris in pots.
![Page 41: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/41.jpg)
Foliar symptoms: note leaf debris.
www.ct.gov/caes
![Page 42: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/42.jpg)
Symptoms in propagation flat.
www.ct.gov/caes
![Page 43: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/43.jpg)
Infected cuttings in propagation bed in VA.
www.ct.gov/caes
Photo courtesy of Norm Dart
Virginia Department of Agriculture and Consumer Services
![Page 44: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/44.jpg)
Foliar symptoms and canker on cuttings.
www.ct.gov/caes
![Page 45: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/45.jpg)
Infected liners.
www.ct.gov/caes
![Page 46: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/46.jpg)
Symptoms (cont’d)
Plants attempt to regrow, but repeated
infection and defoliation weakens the root
system and leads to plant death,
especially for young plants or new
transplants.
www.ct.gov/caes
![Page 47: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/47.jpg)
Disease Cycle and Spread
Boxwood blight can spread very rapidly
under warm and humid conditions.
In 2011, established boxwood plantings in
Connecticut landscapes were apparently
killed in one season following the
introduction of infected plants.
– 2011 was a particularly moderate, wet year
that included several violent rain events.
www.ct.gov/caes
![Page 48: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/48.jpg)
Weather
2011- Warm, cloudy, and wet
2010- Hot, sunny, and dry
2009- Cool, cloudy, and wet
www.ct.gov/caes
![Page 49: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/49.jpg)
CT Rainfall 2008-2011
www.ct.gov/caes
2010
2011
2009
2008
![Page 50: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/50.jpg)
CT Growing Degree Days 2009-2011
www.ct.gov/caes
Brad 30 yr avg.
2010
2011
2009
![Page 51: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/51.jpg)
Boxwood blight in a residential property.
www.ct.gov/caes
![Page 52: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/52.jpg)
One new plant installed in 2011.
www.ct.gov/caes
![Page 53: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/53.jpg)
www.ct.gov/caes
Boxwood blight in a residential property.
![Page 54: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/54.jpg)
www.ct.gov/caes
Boxwood blight in a residential property.
![Page 55: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/55.jpg)
www.ct.gov/caes
Boxwood blight in a commercial property.
![Page 56: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/56.jpg)
www.ct.gov/caes
Boxwood blight in a commercial property.
![Page 57: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/57.jpg)
Before: established planting with
boxwood blight.
www.ct.gov/caes
![Page 58: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/58.jpg)
After: infected plants were removed.
www.ct.gov/caes
![Page 59: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/59.jpg)
Disease Cycle
Boxwood blight pathogen has a rapid disease
cycle: can be completed in one week.
Temperature range: 41-86 ºF.
Optimum temperature for growth: 77 ºF.
Fungus is sensitive to high temperatures:
killed after 7 days at 91 ºF.
Infections can occur very quickly under warm
(64-77 ºF), humid conditions.
www.ct.gov/caes
![Page 60: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/60.jpg)
Disease Cycle (cont’d)
Spores germinate 3 hours after inoculation
and penetrate plant host tissues within 5
hours.
The fungus does not require a wound to
infect--can penetrate directly through the
plant cuticle or can enter the leaf through
stomata.
High humidity levels or free water on plant
tissues are necessary for successful
infection. www.ct.gov/caes
![Page 61: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/61.jpg)
4 Days after Inoculation
www.ct.gov/caes Photo courtesy of Kelly Ivors, NC State
![Page 62: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/62.jpg)
www.ct.gov/caes
Photos courtesy of Kelly
Ivors, NC State
![Page 63: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/63.jpg)
The Boxwood Blight Fungus
Readily forms fruiting structures on
infected plants.
– These structures (sporodochia) are visible
with a hand lens on the undersides of infected
leaves and on the black lesions on stems.
Sporodochia contain large numbers of
sticky, cylindrical spores (conidia), which
give the sporodochia an angular or
crystalline appearance.
www.ct.gov/caes
![Page 64: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/64.jpg)
Boxwood Blight Fungus (cont’d)
Structures of the fungus called vesicles
form in the sporodochia and protrude from
the main fruiting body.
Spores (conidia) are cylindrical and
hyaline, and usually have one septation (2-
celled).
www.ct.gov/caes
![Page 65: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/65.jpg)
Boxwood Blight Fungus
www.ct.gov/caes
![Page 66: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/66.jpg)
Sporulation on undersurfaces of
leaves.
www.ct.gov/caes
![Page 67: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/67.jpg)
Lesions with sporulation.
www.ct.gov/caes
![Page 68: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/68.jpg)
Distinctive appearance of sporulating
colonies--mixed infection on leaf.
www.ct.gov/caes
![Page 69: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/69.jpg)
Sporulating colonies have a distinctive angular,
“blocky” appearance.
www.ct.gov/caes
![Page 70: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/70.jpg)
Sporodochia on stem lesion.
www.ct.gov/caes
![Page 71: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/71.jpg)
Sporodochium with protruding
vesicles.
www.ct.gov/caes
![Page 72: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/72.jpg)
Sporodochium with vesicles and
spores.
www.ct.gov/caes
![Page 73: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/73.jpg)
Vesicles and spores.
www.ct.gov/caes
![Page 74: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/74.jpg)
Vesicle, spore-bearing structure, and cluster of
spores held together by a slimy matrix.
www.ct.gov/caes
![Page 75: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/75.jpg)
Two-celled spores (conidia).
www.ct.gov/caes
![Page 76: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/76.jpg)
Genotypes of the Boxwood
Blight Fungus
Genotype 1 (G1)
– Identified in United Kingdom, New Zealand,
and North Carolina.
– Considered the “common” strain.
Genotype 2 (G2)
– Identified in Belgium and several other
European countries.
– Has some fungicide resistance—this has
important implications for control.
www.ct.gov/caes
![Page 77: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/77.jpg)
Genotypes (cont’d)
There are substantial differences between
G1 and G2, but very little genetic diversity
within each group.
Suggests two separate introductions of the
exotic boxwood blight fungus into Europe.
www.ct.gov/caes
![Page 78: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/78.jpg)
Diagnosis
Microscopy.
Incubation of 24-48 hours under high
humidity.
Culture on artificial media.
We do not diagnose boxwood blight
based on leaf and stem symptoms.
www.ct.gov/caes
![Page 79: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/79.jpg)
Sporulation in lesion after 24 h
incubation.
www.ct.gov/caes
![Page 80: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/80.jpg)
Disease Spread
Short Distance:
– Spores are splash-dispersed and can be
carried short distances by wind or wind-
driven rain.
Medium Distance:
– Occurs as a result of the activities of
humans (e.g., contaminated boots,
clothing, and equipment), animals, and
birds, since the spores are sticky.
– Movement of debris in runoff water.
www.ct.gov/caes
![Page 81: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/81.jpg)
Disease Spread (cont’d) Long Distance:
– Movement of infected plants (commerce).
– Contaminated trucks and shipping
containers.
– Unintentional movement of asymptomatic
but infected plants.
• Shipping apparently “healthy” boxwood (infected,
but asymptomatic or having very limited outward
symptoms) or boxwood treated with fungicides
that suppress, but do not kill or eradicate the
fungus, to nurseries and landscapes.
• “Trojan horse” or “Typhoid Mary” syndrome.
www.ct.gov/caes
![Page 82: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/82.jpg)
Disease Spread--In Production Infected plant material.
Conditions during propagation.
Pruning and grooming.
Overhead watering.
Runoff water.
Pot-to-pot spacing.
Contaminated tools, flats, equipment,
clothing, and boots.
Leaf debris.
And many more….
www.ct.gov/caes
![Page 83: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/83.jpg)
Survival
Cylindrocladium pseudonaviculatum
survives as mycelium and resting
structures (microsclerotia) in leaves and
cankers on infected plants and in leaf
debris (fallen, infected leaves).
– Reported to survive for at least 5 years in
decomposing boxwood leaves.
www.ct.gov/caes
![Page 84: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/84.jpg)
Microsclerotia in tissues.
www.ct.gov/caes
Photos courtesy of Norm Dart
Virginia Department of Agriculture and Consumer Services
![Page 85: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/85.jpg)
Regulatory Status of Boxwood
Blight
Not federally regulated.
USDA-APHIS-PPQ is investigating the
situation to determine if they will take any
action.
Regulatory actions in CT are under the
statutory authority of The Connecticut
Agricultural Experiment Station (CAES).
– Sec. 22-84 and Sec 22-98 of the Connecticut
General Statutes.
www.ct.gov/caes
![Page 86: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/86.jpg)
Regulatory Status of Boxwood
Blight (cont’d)
When Boxwood Blight is detected, a “Stop
Sale Notice” is given to nursery or
business.
– Prevents the sale and movement of infected
plants from quarantined property.
– Many CT properties are voluntarily disposing
of infected plants by burial on the quarantined
property or transporting them to incinerators
(under supervision by CAES inspectors).
www.ct.gov/caes
![Page 87: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/87.jpg)
What has been happening in
Connecticut?
Voluntary burial or incineration of infected
plants.
– Under observation by CAES nursery
inspectors.
Significant financial losses.
www.ct.gov/caes
![Page 88: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/88.jpg)
Infected boxwood bagged for
incineration.
www.ct.gov/caes
![Page 89: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/89.jpg)
Infected plants put into dumpster
for incineration.
www.ct.gov/caes
![Page 90: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/90.jpg)
Dumpster filled with infected boxwood.
www.ct.gov/caes
![Page 91: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/91.jpg)
Field-grown plants prior to destruction.
www.ct.gov/caes
![Page 92: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/92.jpg)
Infected plants dug and roots exposed
prior to burial: note healthy root
systems.
www.ct.gov/caes
![Page 93: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/93.jpg)
Burial of infected boxwood.
www.ct.gov/caes
![Page 94: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/94.jpg)
Infected, potted boxwood
readied for burial.
www.ct.gov/caes
![Page 95: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/95.jpg)
Burial of potted boxwood.
www.ct.gov/caes
![Page 96: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/96.jpg)
Infected boxwood in NC nursery “holding
area” for incoming/outgoing plants.
www.ct.gov/caes Photo courtesy of Kelly Ivors, NC State
![Page 97: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/97.jpg)
Burning leaf debris in NC holding area.
www.ct.gov/caes Photo courtesy of NC Department of Agriculture
![Page 98: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/98.jpg)
www.ct.gov/caes Photo courtesy of NC Department of Agriculture
![Page 99: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/99.jpg)
Tossing infected boxwood into pit for burning in NC.
www.ct.gov/caes Photo courtesy of NC Department of Agriculture
![Page 100: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/100.jpg)
Burning infected plants in NC.
www.ct.gov/caes Photo courtesy of NC Department of Agriculture
![Page 101: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/101.jpg)
Current and Future Work at CAES:
Determine Genotype
What genotype(s) is present in CT?
CAES has over 40 isolates of the fungus
collected from locations throughout the
state.
Using molecular techniques (PCR-RFLP) to
determine the genotype(s) present in CT.
www.ct.gov/caes
![Page 102: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/102.jpg)
Current and Future Work at CAES:
Biology
Can the fungus colonize the roots?
Roots appear healthy, but if the fungus
colonizes the roots, could this be a source of
infection?
How does the fungus survive in CT and
New England?
Environmental requirements for survival and
infection.
www.ct.gov/caes
![Page 103: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/103.jpg)
Current and Future Work at CAES:
Fungicide Efficacy
What fungicides are most effective?
CAES has begun testing registered and
experimental fungicides to determine if
more efficacious products are available.
Develop a fungicide regime for managing
the disease.
www.ct.gov/caes
![Page 104: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/104.jpg)
Current and Future Work at CAES:
Best Management Practices
What BMPs should the industry follow?
CAES is developing BMPs for managing
boxwood blight.
Can highly susceptible varieties be used
as indicator or trap plants?
What are the most effective sanitizing
agents for containers or equipment?
www.ct.gov/caes
![Page 105: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/105.jpg)
Other Boxwood Diseases
Volutella Leaf Blight and Canker
Macrophoma Leaf Spot
www.ct.gov/caes
![Page 106: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/106.jpg)
Volutella Leaf Blight and Canker
Causal Agent: Volutella buxi
(Pseudonectria rousseliana) (fungus)
www.ct.gov/caes
![Page 107: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/107.jpg)
Volutella Blight-distinctive salmon-pink
sporulation.
www.ct.gov/caes
![Page 108: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/108.jpg)
Macrophoma Leaf Spot
Causal Agent: Macrophoma candolleri
(fungus)
www.ct.gov/caes
![Page 109: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/109.jpg)
Macrophoma Leaf Spot
www.ct.gov/caes
![Page 110: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/110.jpg)
Managing Boxwood Blight
www.ct.gov/caes
![Page 111: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/111.jpg)
Management Strategies
1. Start with pathogen-free material by
purchasing from reputable suppliers,
nurseries, or garden centers.
– Avoid purchasing from infested areas.
– Request a history of fungicide treatments with
each shipment (fungicide name, application
rate and time).
– Carefully inspect plants or cuttings for
symptoms at the time of purchase or when
received from supplier.
www.ct.gov/caes
![Page 112: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/112.jpg)
Management Strategies (cont’d)
2. Newly purchased plants or rooted
cuttings should be isolated from existing
boxwood plantings or production areas in
nurseries for at least one month, but
preferably for several months.
– Keep plants labeled or barcoded to be able
to track the source.
– Avoid co-mingling of plant material from
different sources.
– Holding area should have a surface that can
be cleaned of plant debris.
www.ct.gov/caes
![Page 113: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/113.jpg)
Management Strategies (cont’d)
3. Keep accurate, detailed records of:
– Plants received and complete history while
in the nursery;
– Propagation of plant material;
– Mortality due to any cause;
– All chemical/fertilizer applications;
– Weather records, if available.
www.ct.gov/caes
![Page 114: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/114.jpg)
Management Strategies (cont’d)
4. Space plants to maximize air circulation
and minimize conditions favorable for
disease development, when possible.
www.ct.gov/caes
![Page 115: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/115.jpg)
Management Strategies (cont’d)
5. Avoid overhead watering or working with
plants when they are wet.
– Water is important for the spread and
development of boxwood blight.
www.ct.gov/caes
![Page 116: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/116.jpg)
Management Strategies (cont’d) 6. Sanitation is critical for eliminating and
reducing inoculum, since the fungus can
survive in plant debris for up to five years.
– Accomplished by raking, vacuuming, and
removing leaf debris.
– In commercial field plantings, burning plant
debris with a propane torch is an option.
– Monitor plant debris in run-off water.
– Work in blocks with infected plants last and
after completing work with healthy plants.
– Sanitize all shipping containers, benches,
and equipment.
www.ct.gov/caes
![Page 117: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/117.jpg)
Propane torch used to burn infected
boxwood and leaf debris in field in NC.
www.ct.gov/caes Photo courtesy of NC Department of Agriculture
![Page 118: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/118.jpg)
Management Strategies (cont’d)
7. Scout and inspect all boxwood plants
daily or weekly.
– As soon as boxwood blight symptoms
are detected, immediately pull and
remove whole plants and place them in
plastic bags to avoid carrying infected
material through a nursery or landscape.
– Infected plant material should NOT be
composted.
www.ct.gov/caes
![Page 119: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/119.jpg)
Management Strategies (cont’d)
8. If you observe suspicious symptoms on
boxwood, it is important to have the disease
accurately identified by a specialist (plant
pathologist).
– For example, in CT:
• The Plant Disease Information Office (CAES):
http://www.ct.gov/caes/pdio.
• UCONN Home & Garden Center:
http://www.ladybug.uconn.edu/.
www.ct.gov/caes
![Page 120: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/120.jpg)
Management Strategies (cont’d)
9. Use indicator plants to monitor disease
levels or to detect new infections.
– Place highly susceptible plants, such as B.
sempervirens ‘Suffruticosa,’ in propagation
areas or blocks to use as “trap” plants.
www.ct.gov/caes
![Page 121: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/121.jpg)
Management Strategies (cont’d)
10.Planting less susceptible species of
boxwood or alternatives to boxwood can
reduce the potential for disease.
– Examples of alternative plants include some
dwarf cultivars of Ilex crenata, Pieris japonica,
Rhododendron spp., and Taxus baccata.
www.ct.gov/caes
![Page 122: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/122.jpg)
Management Strategies (cont’d)
11.Fungicides.
– FUNGICIDES ARE NOT CURATIVE.
– Follow a preventative program that includes
different products with different modes of
action (FRAC groups).
– Products differ significantly in their mode of
action (e.g., some are more effective in
inhibiting spore germination; others are more
effective at inhibiting mycelial growth).
www.ct.gov/caes
![Page 123: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/123.jpg)
Management Strategies (cont’d)
For commercial producers:
– Azoxystrobin (Heritage**)
– Boscalid + pyraclostrobin (Pageant**)
– Chlorothalonil (Bravo Ultrex, Daconil, Docket)
– Fludioxonil (Medallion**)—some phytotoxicity?
– Mancozeb (Dithane, Fore, Protect)
– Pyraclostrobin (Insignia**)
– Triflumizole (Terraguard**)
** Effective for other Cylindrocladium species.
www.ct.gov/caes
![Page 124: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/124.jpg)
Management Strategies (cont’d)
For homeowners:
– Chlorothalonil
– Mancozeb
www.ct.gov/caes
![Page 125: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/125.jpg)
CAES “Boxwood Blight Team”
Mary K. Inman, Technician, Plant Disease
Information Office
Dr. Sharon M. Douglas, Plant Pathologist
Dr. Victoria L. Smith, Deputy State
Entomologist
Tia Blevins, Jeff Fengler, Steve Sandrey,
and Peter Trenchard, CAES Inspectors
www.ct.gov/caes
![Page 126: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/126.jpg)
Acknowledgements
All boxwood blight photos from
Connecticut are from CAES and include
contributions courtesy of S. M. Douglas,
M. K. Inman, V. L. Smith, and P. W.
Trenchard.
www.ct.gov/caes
![Page 127: Boxwood Blight- A New Threat to Boxwood in the U.S. · PDF fileBoxwood Blight- A New Threat to Boxwood in the U.S. ... –Requested sample of symptomatic plants. ... –Identified](https://reader031.vdocuments.us/reader031/viewer/2022013006/5a8e83a57f8b9a085a8d3bd0/html5/thumbnails/127.jpg)
www.ct.gov/caes
Thank you! Questions?