Fall webworms form a tent on a tree at Hartman Creek State Park in Waupaca County, August 2026. / Photo Credit: Wisconsin DNR
By Bill McNee, DNR Forest Health specialist, Oshkosh;
Bill.McNee@wisconsin.gov or 920-360-0942
The native insect known as fall webworm (Hyphantria cunea) has been generating calls from curious property owners over the past few weeks.
By Carter Hellenbrand, DNR Invasive Plant Field Specialist, Fitchburg;
Carter.Hellenbrand@Wisconsin.gov
Princess tree growing in a hardwood forest. / Photo Credit: Nancy Loewenstein, Auburn University, Bugwood.org
Note: This is the fifth and final installment in the Forest Health News “Invasives Spotlight” 2026 series, a monthly series of Forest Health News articles.
It may have enormous heart shaped leaves, fragrant flowers and a name fit for royalty, but this botanical princess can quickly become an issue in forests.
Princess tree (Paulownia tomentosa) is a non-native invasive deciduous tree that can grow to be over 60 feet in height. It is a prolific seed producer, with individual capsules containing up to 2,000 winged seeds each. These seeds are readily dispersed by wind and waterways.
Not only does this species reproduce via seed, but it also can spread vegetatively through adventitious buds on its roots. When the tree is damaged, burned or cut, root suckers are often produced from these adventitious buds. The sprouts that form from these root suckers can grow up to 15 feet in a single growing season, resulting in more princess trees and a bigger problem.
Princess trees grow in a variety of habitats including forests, stream banks and roadsides. Due to its large leaves, typically ranging from 5 to 12 inches long but sometimes reaching 2 feet in length on juvenile trees, this species easily shades out surrounding vegetation and prevents native tree regeneration. This will ultimately lower the biodiversity of the ecosystem wherever this invasive tree is found.
A native of eastern Asia, princess tree was first introduced into North America as an ornamental and had been planted widely throughout the United States before becoming a regulated species.
In Wisconsin, princess tree is listed as prohibited under the Invasive Species Rule NR40. The rule makes it illegal to possess, transport, transfer or introduce this species in Wisconsin. There have been positive detections for this species in Dane, Grant, Waukesha, Milwaukee, Racine, Trempealeau and Door counties, but the overall distribution is still thought to be limited at this time.
Large oval to heart shaped leaves of princess Tree. / Photo Credit: Nancy Loewenstein, Auburn University, Bugwood.org
Leaves: Broadly oval to heart-shaped and are very large, ranging from 5 to 12 inches long and 5 to 9 inches wide on more mature plants. Leaves can be more than 2 feet long on juvenile plants or stump sprouts.
Flowers: Bloom in early spring, tubular flowers appear in showy pyramidal clusters, are lavender in color and produce a vanilla fragrance.
Fruit: Seed is contained in clusters of green oval-shaped capsules that turn brown once mature. Each individual capsule contains up to 2,000 winged seeds.
Tubular princess tree flowers that are lavender in color and grow in clusters. / Photo Credit: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Green, oval shaped capsules that hold up to 2,000 princess tree seeds and will change color to brown once fully mature. / Photo Credit: Robert Vidéki, Dcoronicum Kft., Bugwood.org
Northern Catalpa: Tree with large heart shaped leaves that closely resemble princess tree. However, catalpa has bell shaped white flower clusters and produces long slender bean-like seed pods instead of the capsules. The center of a princess tree stem, also known as a pith, is hollow or chambered on the inside while the pith of northern catalpa is solid without chambers.
There is a limited number of known populations of princess tree in Wisconsin. Eradication is still possible. If you think you have found princess tree, please report it to Invasive.Species@wisconsin.gov. At a minimum, please include the location and clear photos of the plant’s identifiable features. Other important details such as population size and landownership are also encouraged.
Lookalikes
White, bell-shaped flower clusters of Northern catalpa. / Photo Credit: Dow Gardens, Dow Gardens, Bugwood.org
Northern Catalpa: Tree with large heart shaped leaves that closely resemble princess tree. However, catalpa has bell shaped white flower clusters and produces long slender bean-like seed pods instead of the capsules. The center of a princess tree stem, also known as a pith, is hollow or chambered on the inside while the pith of northern catalpa is solid without chambers.
Northern catalpa long and slender seed pods. / Photo Credit: Tom DeGomez, University of Arizona, Bugwood.org
There is a limited number of known populations of princess tree in Wisconsin. Eradication is still possible. If you think you have found princess tree, please report it to Invasive.Species@wisconsin.gov. At a minimum, please include the location and clear photos of the plant’s identifiable features. Other important details such as population size and landownership are also encouraged.
Small plants can be hand-pulled or dug up, but be sure to remove the whole root system as best you can, to keep new sprouts from developing. Due to this plant’s extensive root system, herbicide is the most effective option at removing this tree species. Cut stump applications using systemic herbicide is the most effective control technique. Be sure to read the full directions on the herbicide label to determine mixing ratios, application rates and required safety measures.
A Wisconsin map showing results of a beech leaf disease survey that ran from 2023 to 2026. / Graphic Credit: Wisconsin DNR
By Art Kabelowsky, DNR Forest Health Communications, Fitchburg;
Arthur.Kabelowsky@wisconsin.gov; 608-335-0167
To date, there have been no confirmed discoveries of beech leaf disease (BLD) in Wisconsin landscape, and we are on the lookout for this disease.
The disease is primarily found on American beech (Fagus grandifolia) but can also be found on ornamental species like European, Oriental, and Chinese beech (F. sylvatica, F. orientalis, and F. engleriana). Although it has not yet been found in Wisconsin, recent discoveries of the disease in Michigan and other states highlight the continued importance of monitoring BLD’s expansion.
Continue reading “DNR Participates In Beech Leaf Disease Detection Survey”
A hunter prepares to safely climb into a tree stand. Hunters are advised to stay away from ash trees when choosing a tree to use for their stand, due to the possibility of hidden damage to the tree due to emerald ash borer. / Photo Credit: Wisconsin DNR
By Wisconsin DNR
As deer hunters begin to scout for suitable tree stand locations, the Wisconsin Department of Natural Resources (DNR) warns hunters to avoid placing their deer stands in or near ash trees.
That’s because of the scourge of emerald ash borer (EAB), which has been confirmed present in all 72 Wisconsin counties. It has already left most ash trees in the southern half of Wisconsin dead or dying, along with many in Door County and the Mississippi River counties.
Continue reading “Avoid Ash Trees When Scouting For Deer Stand Locations”
A female Asian longhorned beetle has a shiny appearance, bright spots and black-and-white striped antennae. / Photo Credit: Bugwood.org
By Michael Hillstrom, DNR Invasive Forest Pest Coordinator
Michael.Hillstrom@wisconsin.gov
More than 300 species of longhorn beetles inhabit the Midwest. The invasive Asian longhorned beetle (ALB) is not yet one of them, with no Wisconsin populations reported.
But ALB’s potential for damage is great enough that state agencies are asking members of the public to be on the lookout for the insect — and to avoid being confused by a relative lookalike.
Continue reading “Tips For Identifying Asian Longhorned Beetle And Lookalikes”
Alex Hornung, Wisconsin DNR Forest Health specialist for Central Wisconsin, discusses the tree disease phomopsis with Chief Forester Heather Berklund during a site visit near Minocqua in July 2026. / Photo Credit: Wisconsin DNR
By Art Kabelowsky, DNR Forest Health Communications, Fitchburg;
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167
Alex Hornung, the Wisconsin Department of Natural Resources Forest Health Specialist for Central Wisconsin, will discuss oak wilt biology at a workshop this month.
Hornung will take part in a Wisconsin Forestry Center/Wisconsin Natural Resources Foundation workshop on oak wilt biology and management, focused on information for landowners and the public. The discussion will take place from 1 to 3:30 p.m. Tuesday, Aug. 18, at Schmeeckle Reserve, 2419 N. Point Drive, Stevens Point. She will be joined by Dr. Holly Petrillo, Professor of Forestry at the University of Wisconsin-Stevens Point.
Continue reading “Forest Health Staffers Plan Public Appearances”
A field at the Coulee Experimental Forest near La Crosse is infested by Japanese stilt grass. / Photo Credit: Wisconsin DNR
By Jenn Janness, DNR Urban Forestry Communications
The Wisconsin Department of Natural Resources will hold a virtual public hearing on a permanent rule to revise Ch. NR 40, relating to changes to invasive species regulations.
Meeting details:
Continue reading “Public Hearing On Invasive Species Regulations Set”
The front page of the Wisconsin DNR’s new Forest Health Fact Sheet on oak decline. / Graphic Credit: Wisconsin DNR
By Art Kabelowsky, DNR Outreach and Communications, Fitchburg
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167
The Wisconsin Department of Natural Resources Forest Health team has published two new fact sheets, bringing the total count of its fact sheet offerings to 26.
The new fact sheets:
The fact sheets are designed in full color, with photos, and are meant to be printed out for reference or to carry into the field. They can also be viewed online. They can be printed on standard letter-sized paper. Most fact sheets are two pages, meant for two-sided printing; a few are four-page documents.
A complete directory of links to all DNR Forest Health fact sheets is available online.
Oak trees with thin canopies experiencing decline following spongy moth defoliation and drought in the prior few years. / Photo Credit: Wisconsin DNR
By River Mathieu, DNR Forest Health Specialist, Fitchburg
River.Mathieu@wisconsin.gov
Oak decline is a complicated forest health issue impacting oak forests in Wisconsin.
In the past few years, oak decline has been recorded in several regions of Wisconsin, primarily linked to spongy moth defoliation and drought conditions that occurred from 2022-2024.
As the summer months of 2026 continue to unfold, oak decline may continue in areas previously impacted by spongy moth and drought.
A red hailstone infestation in Dane County blankets surrounding vegetation and can be seen climbing into trees. / Photo Credit: Wisconsin DNR
By Carter Hellenbrand, DNR Invasive Plant Field Specialist, Fitchburg
Carter.Hellenbrand@wisconsin.gov
Note: This is the third installment in the Forest Health News “Invasives Spotlight” series, a series of articles released monthly during the growing season.
What is heart-shaped and hairy all over? Red hailstone!
Underground tubers of red hailstone. The tubers easily break off to create new plants. / Photo Credit: Wisconsin DNR
Also known as golden creeper or Manchu tubergourd (Thladiantha dubia), this invasive perennial vine can grow 18 feet in a single growing season and spreads through underground potato-like tubers that break off from the root system to create new populations.
