NYC Parks Director of Forestry-Brooklyn Andrew Ullman on Containing Oak Wilt

owleaves1NYC Parks Director of Forestry for Brooklyn Andrew Ullman shares news of oak wilt containment efforts in that borough.

The image at left shows how oak wilt appears on the leaves of white oak (A) and on red oak (B). The leaves fall prematurely, with some green still present, from the affected trees.   

Andrew Ullman:

To date, there has only been one confirmed case of oak wilt in NYC (Brooklyn) though there are several known outbreaks on Long Island. Oak wilt was first confirmed in Brooklyn in Green-Wood Cemetery during the fall of 2016. It should be noted, this tree was on private property and therefore not under the jurisdiction of NYC Department of Parks and Recreation (NYC Parks). NYC Parks has sampled about a dozen trees that are presenting possible oak wilt symptoms. We are currently awaiting the results from the lab and expect to have them within the next few weeks.

The potential impacts on NYC’s urban forest are significant. Citywide, there are nearly 90,000 street trees in the oak genus. Oaks make up roughly 13% of our street trees, and there are many more oaks growing in our parks and natural areas. Oak wilt, caused by Ceratocystis fagacearum, is a lethal vascular wilt fungi. Symptoms include wilting, defoliation, and ultimately death of the host tree. The disease is transmitted by root grafts or insects and affects host trees in a manner similar to Dutch elm disease.

After the confirmed case of oak wilt in Brooklyn, NYC Parks created a proactive inspection program to inspect trees within the boundary established around the confirmed infection site. Parks has inspected all of the oaks trees growing on the streets and in our parks within that boundary. Between NYC Parks inspectors and our friends at Trees New York, we looked at more than 3,000 oak trees as part of this program. We have also created a contract specifically for managing oak wilt. The work completed under this contract will aid us in our efforts to control the spread of oak wilt if we do find it has spread beyond the initial infection site.

Additionally, we are working closely with NYSDEC, Green-Wood Cemetery, and Cornell University’s Plant Pathology Lab to coordinate response and share information. Finally, we are also limiting non-emergency work on oak trees during the growing season to limit the likelihood of spreading the disease.

Please see as well a previous post about preventing the spread of oak wilt with DEC Oak Wilt Operations Coordinator Jennifer Kotary.

 

 

Urban Forestry in the News: Goats, David Nowak/i-Tree, Pelham Bay Park Research, more

goat Hausziege_04In “Can Hungry Goats Restore Urban Forests?” writer Jessica Leigh Hester describes how officials are using a herd of goats in Brooklyn’s Prospect Park to browse invasive plants that took hold after Hurricane Sandy blew down trees, leaving open earth exposed to sunlight. The herd is on loan from Green Goats Farm in Rhinebeck, New York. Using goats for urban vegetation management hasn’t always turned out well, but this project seems to be on the right track.

(above) Photographer: Armin Kübelbeck, CC-BY-SA, Wikimedia Commons

dnowak

In “What are Trees Worth to Cities?” Syracuse-based lead researcher David Nowak of the U.S. Forest Service’s Northern Research Station talks about i-Tree, the tree software that he helped develop. He goes on to talk about the critical importance of assigning a dollar value to our urban forests and the many benefits they provide—then sharing that data with key decision makers. “Money drives decisions,” Nowak says.

MarkHostetler_avatar-160x160In “Why Conserve Small Forest Fragments and Individual Trees in Urban Areas?” Dr. Mark Hostetler says, “For many developers and city planners, it takes time and money to plan around trees and small forest fragments. Often, the message from conservationists is that we want to avoid fragmentation and to conserve large forested areas. While this goal is important, the message tends to negate any thoughts by developers towards conserving individual mature trees and small forest fragments.” Hostetler goes on to discuss why forest fragments are important; he goes into depth about the role of forest fragments in the lives of migrating birds but also touches on the many other cumulative ecosystem benefits we know that urban trees/forest fragments provide, including carbon sequestration and shade.

pelham bay parkIn “Long-term Outcomes of Forest Restoration in an Urban Park,” NYC and USDA Forest Service Researchers compared restored and unrestored forest sites 20 years after initiating restoration. The sites are located within the Rodman’s Neck area of Pelham Bay Park, in the northeast corner of the Bronx in New York City. Some of the major implications for restoration practice that the researchers concluded from the findings of this study are that:

  • Urban forest restoration practices such as targeted removal of exotic invasive species and planting native tree species can increase species diversity and vegetation structure complexity. These effects can be seen two decades after restoration is initiated.
  • Targeted removal of exotic invasive plant species alone (i.e. without planting native trees) can increase numbers of exotic invasive shrubs and vines.
  • Urban forest restoration requires some level of continued maintenance to ensure success. Additional studies are needed to determine optimal levels (intensity and frequency) of intervention.

Plant MOre Trees MissouriIn “Online Tree Planting Program Software Applications” (pp 12-15) Plan-It Geo Founder Ian Hanou shows how two community forestry groups—Pennsylvania Horticultural Society and Forest ReLeaf of Missouri—used Cloud-based applications to accomplish their tree planting goals. He also provides an accessible primer on these tools.