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Oak Wilt Analysis

The Cornell Plant Disease Diagnostic Clinic (PDDC), in conjunction with the New York State Department of Environmental Conservation (NYS DEC) and the New York State Department of Agriculture and Markets (NYS DAM) has been surveying trees across New York State (NYS) for the plant pathogen, Ceratocystis fagacearum. This fungus causes a devastating disease known as Oak Wilt that may kill highly susceptible trees such as members of the red oak family, within the same season that symptoms develop.

Because this potentially devastating pathogen had been identified twice in one upstate NY community within a period of 6 years, we felt a broader investigation was needed. Searching potentially favorable sites for the oak wilt pathogen could help to identify areas where the pathogen may be present early enough for management efforts to be more effective.

This project will also help us get a better understanding of the general health of red oaks across the state, and where the pathogen has been found in other locations throughout the state, where additional eradication efforts are needed. Plant pathologists and other green industry specialists that work with tree health have learned through numerous case studies that the earlier an infection is found, the greater the chances are for successful eradication.

As a result of this project, the pathogen has been detected in additional areas. For more information, please see the sections below regarding the 2016 and 2017 finds.    

2017 Oak Wilt Findings

The PDDC processed 143 oak wilt suspect samples in 2017. In 2016, four (4) sites on Long Island, one (1) in Brooklyn and one (1) in Canandaigua produced positive identifications of the oak wilt pathogen. None of these locations or the surrounding areas around these sites, produced positive results in 2017. Of the 143 samples, only two (2) sites resulted with positive identifications of the oak wilt pathogen. Unfortunately, both positives were found in Schenectady County, near the first find of oak wilt in New York State in 2008. The first positive was found in the Sanders Preserve, approximately 3 miles east of the original oak wilt site and the second positive was found at a residence around 7 miles to the Northwest of the original site. Plans to continue surveying in 2018 are under way.

2016 Oak Wilt Findings

Cornellís Plant Disease Diagnostic Clinic Identifies the Pathogen that causes Oak Wilt on Long Island

On August 2, 2016, the NYSDEC announced that we identified the oak wilt pathogen at a new location, the second in New York State. The pathogen was found on trees from Central Islip on Long Island. The trees were submitted to the Plant Disease Diagnostic Clinic after a concerned arborist had ruled out a number of common diseases and disorders. He had seen some of the informational materials we distributed, specifically the BOLO-Be On the Look Out postcards and he decided to send samples to the Clinic just to make sure he was covering all the bases.

We are thankful to all of the individuals who have diligently pursued answers for the decline of oak trees in these locations.

None of this work could have been done without the support of a Specialty Crop Block Grant and without this project, we may not have found this new site in an early infection stage which is key for successful eradication efforts. The grant allowed us to develop and distribute the informational marketing materials and it gave us the resources needed to develop and test additional identification methods that we hoped would help us identify the pathogen more quickly and by using different types of testing methods.

See the links in the column to the left of materials provided for information about symptoms to look for, who to contact if symptoms are found, and if found on your property, how to submit a sample for processing. See the NYS-DEC article at:

Cornellís Plant Disease Diagnostic Clinic Identifies the Pathogen that causes Oak Wilt in Canandaigua, NY.

On October 25, 2016, NYSDEC announced that the oak wilt pathogen had been identified at a third location in New York State, the second new location this year. This identification follows from a concerned homeowner contacting Cornell Cooperative Extension, with subsequent submission of a suitable sample to the Plant Disease Diagnostic Clinic for analysis. For more information, please see the NYS-DEC press release for this find at: Additional information may also be found on the NYS-DEC website at:

NY News Daily Article on Oak Wilt in Brooklyn
WCBS Channel 2 News Inteview about Oak Wilt
Associated Press on oak wilt
Cornell Chronical Article on finding oak wilt in 6 new locations.
Sample Submission Instructions and Form
New 2017 Oak Wilt Poster
Oak Wilt Postcard
Oak Wilt Assessment by G. W. Hudler (2008)
YouTube Video by G. W. Hudler (2008)
Additional References and Publications