Boxwood blight continues to spread

Pest and disease
 
New Jersey, Delaware confirmed the presence of the disease earlier this summer.

| August 7, 2013

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Samples of boxwood infected with the fungus Cylindrocladium pseudonaviculatum, the cause of boxwood blight, were confirmed by the Rutgers Plant Diagnostic Laboratory and the New Jersey Department of Agriculture Laboratory in July. This was the first report of the disease is New Jersey.
Earlier in the summer, boxwood blight was confirmed in a retail nursery in Delaware.
The latest reports bring the total number of states with confirmed findings to 12 (CT, DE, MA, MD, NC, NJ, NY, OH, OR, PA, RI, VA).

Initial symptoms of boxwood blight appear as light brown spots on the leaves. Spots enlarge, often with concentric circles or a zonate appearance, until entire leaves are blighted and shed. The fungus also infects woody tissues, which results in dark brown to black “diamond-shaped” lesions and stem dieback. Defoliation and stem dieback are rapid. Be aware that boxwood blight spreads very quickly in warm and humid conditions and has the potential to do significant damage to your plantings, said Richard Buckley of Rutgers Cooperative Extension.

For comprehensive information on boxwood blight, visit www.boxwoodblight.org.


Photos by Sabrina Tirpak, Rutgers

Some boxwood varieties show tolerance to blight

Industry News A report shows a wide range in susceptibility to boxwood blight.

| October 23, 2012

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From ANLA's knowledge center:

A recent report from the North Carolina State University Cooperative Extension showed considerable variability in the susceptibility of Boxwoods (Buxus spp.) to Boxwood Blight (Cylindrocladium pseudonaviculatum). The researchers evaluated twenty-four varieties and found B. sempervirens ‘Suffruticosa’ to be the most susceptible. Unfortunately, Suffruticosa (Common Boxwood or English Boxwood) is the mostly commonly planted Boxwood variety in the United States. However, the authors did find nine varieties that, they determined, were “moderately tolerant” to “tolerant” with the most tolerant being B. microphylla var. japonica ‘Green Beauty’.

Boxwood Blight is a recently introduced plant pathogen in the North America, first confirmed in October of 2011. The disease can cause significant leaf drop and stem lesions creating bare and brown patches. It has been discovered in ten states (CT, OH, OR, MA, MD, NC, NY, RI, PA, VA) and three Canadian provinces (BC, ON, QC).

To download the NC State report click here.

Boxwood blight found on pachysandra in Connecticut landscape

Pest and disease
Infection found near newly planted boxwoods

From Sharon Douglas at the Connecticut Agricultural Experiment Station (CAES):

A natural infection of pachysandra in the landscape by Cylindrocladium pseudonaviculatum, the boxwood blight fungus, was confirmed by CAES plant pathologists on 29 June 2012. The pachysandra sample had been collected by a CAES inspector while visiting a residential property in Fairfield County that had installed B&B boxwood plants in May 2012.  These plants had been confirmed by CAES to be infected with boxwood blight one week prior to the visit. The inspector noticed that an established bed of pachysandra bed adjacent to the infected boxwood had unusual, foliar symptoms, so he collected the sample to bring to the diagnostic lab for examination.

Symptom included small to larger necrotic lesions with well-dileneated margins on the leaves. All of the necrotic lesions had distinct, diffuse yellow haloes. No lesions were observed on the stems and no defoliation had occurred. The overall color of the pachysandra leaves were normal and dark green.

The CAES had previously reported pachysandra as a boxwood blight host, but it was innoculated in the lab and greenhouse.

Issue no. 2 of the Home, Yard & Garden Newsletter is now available on the Web

IN THIS ISSUE:

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Weekly Issues Begin

The Home, Yard, and Garden Pest Newsletter will be issued weekly from this issue through May and June. In July, we will switch to issues every other week.

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Weather & Insect Emergence

Cooler weather over the last two weeks has helped bring the insect activity pattern closer to normal. Based on growing degree days with a base temperature of 50 degrees F, southern Illinois is slightly over two weeks ahead of last year, central Illinois is three weeks early, and northern Illinois is slightly over four weeks early.

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Scouting Watch

The most common pests that should be in susceptible treatment stages are discussed. Be sure to scout to verify that the susceptible stages of the insect are present before applying controls.

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Emerald Ash Borer

Emerald ash borer should be flying in both central and southern Illinois and will continue to emerge and fly for several weeks. Although insecticide sprays against the adults are effective, applications of systemic insecticides between 50% leaf expansion in spring until approximately six weeks before leaf fall are recommended.

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Black Cutworm

There have been large early flights of black cutworm moths throughout Illinois for several weeks. Golf course personnel should be on the lookout for black cutworm larval infestations in bentgrass, ryegrass, and fescue. Cold temperatures have little effect on the survival of eggs and larvae.

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A New Disease to the United States, but not yet detectedin Illinois:  Boxwood Blight

In October of 2011, Boxwood Blight (Cylindrocladium pseudonaviculatum) (syn. C. buxicola), was detected in North Carolina and Connecticut.  Later, there were more detections of this disease in the United States.

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Brown rot vs. Fire Blight

Brown Rot can cause blossom blight, stem canker, and dieback of peach, cherry and other stone fruit species. The visual symptoms of brown rot have many similarities to symptoms caused by fire blight on apple, pear and many other species in the rose family. The pathogens that cause brown rot and fire blight are very different.

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NPDES

On November 1, 2011, the federal requirement for an NPDES permit for certain pesticide applications went into effect.

Stay on Top of Boxwood Blight

From Nursery Management:

Boxwood blight, a new and lethal pathogen, has growers and landscape professionals on alert. The fungus Cylindrocladium buxicola (syn. C. pseudonaviculatum) was confirmed just a few short months ago in late October 2011 by the USDA.

In early October 2011, the Connecticut Agricultural Experiment Station (CAES) received samples of boxwoods with leaf spots and blights, rapid defoliation, distinctive black stem cankers and severe dieback. It’s not clear how the fungus arrived in Connecticut, but boxwood blight is found throughout Europe. Last year’s discovery in Connecticut was the first reported outbreak in the United States. Since October 2011, the disease has been confirmed by USDA in North Carolina, Virginia, Rhode Island, Maryland, Massachusetts, Oregon, New York and Pennsylvania. As these popular landscape plants are shipped during March and April, it’s likely that boxwood blight will show up in other states.

Boxwood blight has been reported to occur on all Buxus species, but some cultivars may be more susceptible than others, said Sharon Douglas, plant pathologist at CAES. (See Table 1) English boxwood and American or common boxwood appear to be highly susceptible, but the complete host range of this pathogen is not known, she said.

This is a costly pathogen where thousands of infected plants have been destroyed across several states.

For the complete article, including symptoms and control recommendations, go to

http://www.nurserymanagementonline.com/nm0312-boxwood-blight-disease.aspx

Boxwood Blight Confirmed in Ohio

From  Nursery Management:

 
The Ohio Department of Agriculture (ODA) announced the discovery of boxwood blight at the Red Mill Farm of Losely Nursery in Lake County in northeast Ohio. Boxwood blight is a disease caused by a fungus (Cylindrocladium pseudonaviculatum) that threatens the health and sustainability of boxwood plants. This is the first detection of boxwood blight in Ohio.

Boxwood blight was first detected in the United States in North Carolina in October 2011. Plant pathologists in the United Kingdom first identified the disease in the mid-1990’s. It is unclear how the disease was introduced into the United States. To date, Ohio is the 10th state to identify boxwood blight.

The suspect infection was reported to inspectors with the ODA and the Ohio Plant Diagnostic Network (OPDN) who then sent samples to the United States Department of Agriculture – Animal Plant Health Inspection Service (USDA APHIS) for confirmation. Officials at this time are unsure how the disease was introduced into the Red Mill Farm. ODA inspectors have issued a restriction on all boxwood plants located at the Red Mill Farm and will be conducting further sampling.

“Although it is unfortunate to have confirmation on the farm, all known infected plants have
been destroyed and we are working with the Ohio Department of Agriculture to prevent any
further spread of boxwood blight” said Andrew Harding, vice president and general manager of Herman Losely and Son, Inc.

This disease is spread primarily by water (rain splash, irrigation, runoff, etc.), by the movement of plant material in the trade, and through contaminated tools, vehicles, boots, etc. Initial symptoms of the disease on boxwood plants include leaf spots and blights, rapid defoliation, distinctive black cankers on stems, and severe dieback. Most boxwood plants are not killed by the disease, but will become so defoliated as to be aesthetically unacceptable.

Bloxwood Blight: You Tube Video

Boxwood Blight Update

New Host: Pachysandra

Plant pathologists at The Connecticut Agricutural Experiment Station recently identified Pachysandra terminalis (common names: pachysandra, Japanese spurge) as a new host of Cylindrocladium pseudonaviculatum, the fungus that causes Boxwood Blight. Healthy pachysandra plants were inoculated with spores of C. pseudonaviculatum and lesions developed on the leaves ten days after inoculation.  Three weeks after inoculation, many of the leaves with lesions yellowed and dropped. Heavy sporulation of the fungus was observed.  This raises significant concerns about pachysandra as a potential source of inoculum for infection of boxwood and vice versa.  More information will be forthcoming.

(Source)

Boxwood Blight

Have you seen the latest blog from the University of Illinois Plant Clinic? on boxwood blight?