Speakers
Evan Alderman
Evan Alderman is a Co-Coordinator and Agricultural and Natural Resource Extension Specialist with the Pesticide Safety Education Program at Iowa State University. Evan coordinates and produces all specialty crop pesticide continuing instruction courses for the state of Iowa. Evan’s background includes a MS degree from Kansas State University in Horticulture with an emphasis in Turfgrass Science, and a BS degree from Iowa State University in Horticulture with an emphasis in Turfgrass Management.
Scott Carlson
Based in Eldridge, Iowa, Scott Carlson is the lead instructor and consultant for Iowa Arborist Consulting. He imparts his expertise in tree care topics to various audiences, including tree care companies, municipalities, arboretums, and colleges. Scott’s contributions extend to assisting numerous individuals in achieving ISA Certified Arborist status.
Additionally, he provides consulting services, tree risk assessments, tree appraisal, inventories, and legal expert witness services.
Jim Donohoe
Jim Donohoe is the New Plant Development Specialist at J. Frank Schmidt & Son Co., with over 25 years of horticultural expertise focused on hybridization, propagation, and evaluating new ornamental varieties. He has led initiatives in greenhouse management, hybridization experiments, field trials, and the selection of superior cultivars. Jim holds an Associate Degree from Williamson College of the Trades and completed the prestigious Longwood Gardens Grounds Apprenticeship Program. His background spans landscape design, field management, and garden care across multiple states. Jim looks forward to sharing his specialized insights at the 2025 Shade Tree Short Course to advance ornamental horticulture.
Jim Flott
Jim Flott is president of Community Forestry Consultants, Inc. (CFC). CFC provides urban forestry, arboriculture, and horticulture consulting services to individuals, corporations, universities, municipalities, county and state agencies, cemeteries, and golf courses in the United States and Canada. He received his B.S. degree in horticulture from Iowa State University and his M.S. degree in forest pathology from the University of Arizona and has over 50 years work experience in the horticulture, urban forestry, and arboriculture industries. He is an ISA certified arborist and certified municipal specialist; American Society of Consulting Arborists registered consulting arborist; PNW-ISA TRACE instructor and certified tree risk assessor; ISA TRAQ instructor and assessor; and a certified Lantra training instructor.
Richard Hallet
Dr. Hallett (B.S. University of Wisconsin – Madison, M.S. and Ph.D. University of New Hampshire) has spent his career studying tree and forest health in the northeastern U.S., working towards earlier detection of tree stress caused by acid rain, exotic insects and diseases. In 2009 he shifted his research focus from ex-urban forests to urban ecosystems. Currently he is working with a team that has developed an urban tree health assessment app called Healthy Trees Healthy Cities. We are focused on getting more eyes on trees nationwide.
James L. Komen
Class One Arboriculture Inc.
James Komen, a consulting arborist based in California, specializes in risk assessment and tree appraisal, providing invaluable assistance to clients seeking informed management decisions for individual trees and tree inventories. His noteworthy contributions have been featured in publications like Arboriculture & Urban Forestry, Arboricultural Consultant, Palms, Ontario Arborist, and Western Arborist. In addition, James is an ISA TRAQ instructor and shares his expertise by leading workshops on tree appraisal throughout the United States and Canada
Chris Lee
Chris Lee is an expert in organizational culture. He is a sought after speaker, leadership consultant, host of the Parks and Restoration Podcast, and a regular columnist for newspapers in Des Moines County, Iowa. In addition to his leadership consulting, he has served as the Executive Director for Des Moines County Conservation since 2013, is a recognized leader and award-winning business person known for his unique, nature-inspired approach to cultivating healthy organizational ecosystems.
Mike Litterst
As the Chief of Communications for the National Park Service’s National Mall and Memorial Parks, Mike Litterst has been the voice of the cherry blossom trees for more than a decade. He is responsible for media relations, publicity and digital communications at 16 national parks in downtown Washington, including the iconic monuments and memorials of the Mall, Ford’s Theatre National Historic Site and Belmont-Paul Women’s Equality National Monument. A native of the Washington, DC area, Mike received a degree in Recreation and Park Management from Penn State University. In his more than 40 years with the National Park Service, Mike has been at a variety of park sites in the Mid-Atlantic region as well as the National Park Service headquarters Office of Communications.
David McKinney
David McKinney is a horticulturist, ecologist, entomologist, and plant physiologist currently working as the curator at the Iowa Arboretum and Gardens where he manages 160 acres of gardens, prairie restoration, and native woodland. Originally from Colorado, he received three degrees in horticulture from Colorado State University while also coordinating extensive perennial trials and demonstration gardens. He is passionate about native plants, and the interactions between plants and wildlife. On top of his curatorial work David is a writer, speaker, and serves on the AmericanHort Landscape Community Connectors group, recently receiving the Emerging Perennial Professional Award from the Perennial Plant Association.
John Pattee
John Pattee’s deep-rooted experience in agriculture, spanning from farm work to sales and marketing, has equipped him with a comprehensive understanding of crop production. His current role in crop insurance requires a keen eye for detail and a thorough knowledge of various agricultural practices. From conducting nursery inspections and inventory assessments to insuring crops nationwide, including Hawaii’s macadamia nuts and coffee, Texas nurseries, Florida citrus, Arkansas rice and cotton, and Midwest nurseries, John’s expertise is invaluable to the industry.
Gregory Pierce
Greg Pierce is a Partner at RDG Planning & Design, leading their Civil and Water Resource Engineering discipline group. He has over 25 years of experience and is a graduate of the University of Iowa. He is licensed in six states and is a Certified Professional in Erosion and Sediment Control. He has served on the Iowa DNR’s Iowa Stormwater Management Manual Technical Committee since 2012 and has contributed to updates of more than 20 sections of ISWMM.
Chad Rigsby
During his academic career Chad studied the interactions between invasive forest pests and their novel host plants before joining the Bartlett Tree Research Laboratories team in 2018. Based out of The Morton Arboretum outside of Chicago, Chad’s research focuses on a variety of topics centered on trees and their management including pruning, soil, root, and pest management, tree stress, growth-defense tradeoffs, non-structural carbohydrate dynamics, and tree planting practices. Chad also works with Bartlett Tree Experts arborists and other groups to educate on and implement best management practices and science-driven tree care.
Jenn Ripp
Jenn Ripp is an agroforestry educator with the Savanna Institute that also manages and grows their On-Farm Training Program. Jenn has a wide breadth of experience in agriculture, including seed farming, apple orchard, and livestock over the last decade. Her work has brought her to multiple ecoregions working with farmers from all different perspectives. Through this experience she is able to prioritize the nimble, flexible nature of incorporating woody perennials into the landscape to strengthen resilience in food production, water and air quality, and overall community well being.
Mark Rouw
Mark is a life long resident of Iowa and attended Drake University. He recently retired after working 37 years for the Science Center of Iowa. Mark started locating and measuring big trees around 1972. He has been an active volunteer in the Iowa Big Tree Program since it’s inception in 1978. Mark has spent most of his time searching for big trees in Iowa but has found state champion trees in Nebraska, Kansas and Colorado. He has found national champion trees in Iowa, South Dakota, Colorado, Texas and Arizona. For over ten years, Mark has also been documenting the tallest trees in Iowa.
Zach Schumm
Zach is an entomologist with a passion for insect conservation. After earning degrees in entomology and wildlife conservation from the University of Delaware and Utah State University, he now works in insect diagnostics, helping clients identify and manage insect pests. He is dedicated to changing perceptions about insects and promoting their importance in ecosystems.
Amanda Snodgrass
Originally from Iowa, Amanda received her Bachelor of Science and Master of Science in Horticulture from Iowa State University. In 2012 she started her career with the National Park Service, before also spending time with the United States Forest Service and Bureau of Land Management. Most recently, Amanda was an Assistant Field Manager for the Medford District BLM and recently returned to Iowa where she now serves as an Environmental Protection Specialist for the USDA Rural Development Agency. Along with her background in horticulture, botany, and environmental stewardship, Amanda has spent over 10 years leading diverse teams across agencies and programs – from youth crews in the everglades, to search and rescue teams in southern Utah, to teams of resource specialists tasked with protecting our most valuable natural resources.
David Stevens
David is the curator of the living collection of woody plants at the U.W.-Madison Arboretum which is housed in the Longenecker Horticultural Gardens. He is just the third curator since the Gardens’ inception in 1935 to oversee the largest and most diverse collection of woody plants in Wisconsin. His work background includes tree breeding and selection, greenhouse facility management, public garden supervision, and commercial vegetable production. He has a bachelor’s degree in horticulture from Virginia Tech and a master’s degree in horticulture from U.W.–Madison. When not at the Arboretum, he manages his family’s 130-acre certified organic farm by Baraboo with his wife Jane with whom he was awarded the prestigious organic farmer of the year award at the Midwest Organic Farming Conference in 2020.
Grant Thompson
Grant is a landscape architect with RDG Planning & Design. He is a member of the Iowa Urban Tree Council, on the Board of Directors with Trees Forever, and serves on the American Society of Landscape Architects national Biodiversity and Climate Change Committee. His practice and research are centered in horticulture, soil ecology, and urban forestry.
Mark Vitosh
Mark Vitosh is originally from Iowa City, and he has a B.S. and M.S. degrees in forestry from Iowa State University. Mark has been a professional forester since the fall of 1988, and has worked in Oklahoma and Iowa (including Iowa State University). He has been a District Forester with the Iowa DNR Wildlife Bureau since 2000. He assists private landowners in managing their forest resources in Benton, Iowa, Jasper, Johnson, Linn, Muscatine and Poweshiek counties. He loves to hunt mushrooms in the spring.
Randall Vos
Randall is the Commercial Fruit Crops Field Specialist for Iowa State University Extension and Outreach where he provides technical assistance to commercial fruit growers throughout the state. He has a wide range of experience in fruit production. One of his main interests is in woody plant cold hardiness.
Liz Westberg
Liz Westberg is originally educated as a Wildlife Ecologist, earning her B.S. from the College of Natural Resources at the UW – Stevens Point. Since transitioning to the Utility Arboriculture industry in 2018, she has earned the ISA Utility Specialist and TRAQ credentials. Liz manages the training, quality assurance, and safety programs for Growth Solutions – a tree growth regulator application company – and has been speaking on tree and safety topics around the country.
Fred Whitford
Purdue University
Fred Whitford is the Clinical Engagement Professor and Director of Purdue Pesticide Programs. He has served as the Director of the Purdue Pesticide Program since 1991. With a prolific career, Fred has authored over 300 publications, including 8 books and 120 extension bulletins. He’s an accomplished speaker, having delivered more than 6,500 presentations.
Fred’s remarkable contributions to Extension outreach have earned him several prestigious awards, such as the Frederick L. Hovde Award of Excellence in Educational Service to Rural People of Indiana, and the Honorary Master Farmer by Indiana Prairie Farmer and the Purdue University College of Agriculture.
Michael Yanny
Michael, along with his wife Lori, own JN Plant Selections, LLC. They develop and introduce new woody ornamental plants with an emphasis on tough, hardy materials for cold regions of the world. Michael has a B.S. degree from the U of Wisconsin-Madison in horticulture. He learned many of his plant propagation and plant selections skills from the late Herbert F. Trautman. Michael was plant propagator and senior horticulturist at Johnson’s Nursery in Menomonee Falls, WI from 1980 through 2016. A few of the plants he has selected for introduction include: Firebird(R) Crabapple, Red Feather(TM) Arrowwood, Technito(R) Arborvitae, and Star Power(TM) Juniper
Ed Zaworski
Ed Zaworski is an extension specialist at Iowa State University. He worked in the ISU plant and insect diagnostic clinic from 2014-2022 working with the public on various tree related problems among other things. Ed continues to work with Iowa state extension on programs educating the public on tree related plant pests and diseases. Ed also hosts a podcast called I See Dead Plants which showcases research being done on various plant pests and diseases.
Ron Zillmer
Ron Zillmer is the President of Legacy-Trees, LLC, located in Hatfield, Wisconsin. Legacy-Trees has a patent pending on a revolutionary approach to tree production and planting technology.
Ron has a Bachelor of Science Degree in Forestry with an Urban Forestry Emphasis from UW – Stevens Point. During his time at UW – Stevens Point, Ron spent a week assisting Dr. Alex Shigo with a Tree Biology Workshop. This sparked Ron’s keen interest in Tree Physiology and Compartmentalization in particular. This experience led to his Masters of Science Degree in Forestry with a Tree Physiology Emphasis from Purdue University. Ron’s experience at Purdue is where he worked with one of the top Tree Root Physiology scientists in the world, Dr. William Chaney. He worked on developing a tree growth regulator molecule called “Paclobutrazol” that is the active ingredient in Cambistat. Following graduate school, Ron worked for the City of Milwaukee Forestry Division for nine years. During his time with Milwaukee, he also became the President of the Wisconsin Arborist Association and spent six years on the International Society of Arboriculture Arborist Certification Board. In 2000, Ron joined Mid-State Technical College to pursue his dream of building the Urban Forestry Technician Two Year Associate Degree. This program was built to provide hands on training in tree care within a natural resource’s foundation of science-based training. Ron Launched Legacy-Trees in 2017 to develop a better process for producing and transplanting trees.