Scientists & Staff

Charles Flower

Research Ecologist
359 Main Road
Delaware, OH, 43015-8640
Phone: 740-368-0038

Contact Charles Flower


  • University of Illinois at Chicago, Ph.D. Biological Sciences, 2013
  • The Ohio State University, M.S. Ecology, Evolution and Organismal Biology, 2007
  • Lake Forest College, B.A. Biology and History, 2004

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Publications & Products

National Research Highlights

Ash trees.

Understanding Long-Term Impacts of an Invasive, Tree-Killing Pest

Year: 2019

The emerald ash borer has been killing ash trees in the United States for more than two decades. What does that mean for ash populations and the forest ecosystems? Long-term monitoring plot data collected by USDA Forest Service scientists and partners is helping to elucidate the impacts of this invasive pest and to plan management and conservation strategies.

Researcher injecting an ash tree with insecticide.

Genetic Information on Ash Informs Treatments for Emerald Ash Borer 

Year: 2018

Forest managers can use insecticide treatments to protect ash trees from emerald ash borer to conserve the genetic diversity of ash. But which trees should be protected? Research at the Allegheny National Forest is underway to develop new strategies to conserve ash tree diversity.

Photo (1) USDA employee inoculating an American elm tree with the Dutch elm disease fungal pathogens. 
Photo (2) Healthy American elm tree (left) and a tree that has succumb to DED (right).

Forest Service moves American elm tree a big step closer to landscape restoration

Year: 2017

Over the past several decades, mature American elm trees have virtually disappeared from city streets and eastern forests as a result of Dutch elm disease. Forest Service scientists are on the cusp of developing sufficient genotypes to successfully restore new selections of American elm back to the landscape. Dutch elm disease inoculation trials initiated in Ohio in June 2016 yielded American elm cultivars that exhibit low levels of Dutch elm disease-induced decline one year later.


Forest Service scientists develop a cold-hardy American elm tree

Year: 2017

Dutch elm disease largely eradicated mature elm trees from the eastern U.S. in the 1900s. Forest Service scientists are working to create site-adapted Dutch elm disease tolerant elm trees capable of tolerating the cold winters of the Chippewa National Forest in northern Minnesota.

Dead ash trees in an urban forest create a gap in the canopy, allowing sunlight to filter down to other trees and plants.

Understanding effects of emerald ash borer on forests

Year: 2017

As the invasive emerald ash borer swept across Ohio, Forest Service researchers tracked its aftermath as killed ash trees unleashed a cascade of effects in forest ecosystems. Understanding these effects will help managers plan for and mitigate problems in forests throughout the region.

1: Two American elm trees tree on left healthy with dark green foliage while tree on right is diseased and exhibiting light yellow foliage.  
2: Variability in American elm leaf color associated with infection by Candidatus. Phytoplasma trifolii  with leaves on left collected from an infected tree while leaves on right were collected from a healthy tree.

Identification of a clover proliferation group phytoplasma as the probable cause of American elm Ttee mortality

Year: 2017

Forest Service scientists observed premature canopy decline symptoms in elm trees within their research plantations in midsummer 2016. They attributed canopy decline symptoms to a phytoplasma in the clover proliferation group previously not reported to impact forest trees. Mitigation approaches are currently being undertaken.

American elm cuttings growing in the greenhouse. Kathleen Knight, U.S. Department of Agriculture Forest Service.

Elm Disease Resistance Research Gets a Boost

Year: 2016

Great news for disease-tolerant American elm! A grant from The Manton Foundation has provided the Forest Service’s Northern Research Station with an opportunity to accelerate American elm research in collaboration with Nature Conservancy.

Last modified: Thursday, March 29, 2018