By Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665
Tubakia leaf spot (Tubakia dryina) is a leaf disease that typically affects the lower canopy of oaks. It caused some issues in 2021 and is affecting red oak trees in north-central Wisconsin this year as well.
Tubakia creates abnormal blotches and spots on oak leaves that can coalesce. Photo: Wisconsin DNR
By Andrea Diss-Torrance, Invasive Insects Program Coordinator, Madison, Andrea.DissTorrance.wisconsin.gov
Spongy moth* (formerly known as gypsy moth) populations are entering an outbreak phase in southern Wisconsin due to last year’s dry, hot weather. This pest is rising most rapidly in oak-dominated areas, especially in landscaped spaces with turf and high human activity (i.e., parks, picnic areas, campgrounds and yards). This open ground and human disturbance deter spongy moth’s predators and diseases.
Oak trees are more vulnerable to defoliation in disturbance-heavy environments. These oak trees in Middleton, Wisconsin are facing heavy defoliation by spongy moth. Photo: Wisconsin DNR
By Paul Cigan, DNR Forest Health Specialist, Hayward, Paul.Cigan@wisconsin.gov or 715-416-4920
Conifer and hardwood trees have begun showing more apparent and often substantial signs and symptoms of damage from a severe hailstorm that spread across several northwestern Wisconsin counties on May 9, 2022.
The storm produced golf ball-size hailstones and high-speed winds causing catastrophic injury to tree branches and stems, in addition to defoliation. Few tree species were spared in its path. The heaviest impact occurred in northeastern Polk County, where defoliation of aspen and black locust reached nearly 100%, and pine exceeded 90% (Fig. 1). Red and white oaks show more moderate damage.
Figure 1. Polk County had nearly 100% defoliation from a severe May hailstorm. Photo: Wisconsin DNR
Continue reading “Catastrophic Hail Injury To Trees In Northwest Wisconsin”
By Jaqi Christopher, DNR Forest Invasive Plant Specialist, Rhinelander, Jacquelyn.christopher@wisconsin.gov
Giant hogweed is a large invasive species commonly confused with the native look-alike cow parsnip. Although giant hogweed is uncommon in Wisconsin, it’s important to know the difference between the two.
Giant hogweed can invade woodlots and get 8-20 feet tall. Photo Credit: Ramona Shackleford
By Bill McNee, DNR Forest Health Specialist, Oshkosh, bill.mcnee@wisconsin.gov or 920-360-0942
Early photo of EAB adults taken in June 2002, prior to the insect species being identified. Photo: USDA Animal and Plant Health Inspection Service
The beginning of July marked 20 years since we received news of an unidentified beetle that turned out to be the emerald ash borer (EAB), one of North America’s greatest tree killers. On July 1, 2002, DNR forest health staff received an email from USDA Animal and Plant Health Inspection Service about this beetle being associated with declining ash in southeast Michigan:
This is to notify you that in the past few days we have responded to a report of an insect pest feeding on ash in the western suburbs of Detroit. This follows what has been a series of reports of declining ash in this area over the past couple of years. However, in the past we have not been able to associate it with any particular insect or disease. We are now seeing a boring insect emerging from the infested trees in various sites… The adult, which is emerging now, resembles the shape and size of two lined chestnut borer. It is emerald, metallic green in color and leaves a D-shaped exit hole, similar to bronze birch borer… Continue reading “20 Year Anniversary Of Emerald Ash Borer Confirmation In North America”
By Paul Cigan, DNR Forest Health Specialist, Hayward, Paul.Cigan@wisconsin.gov or 715-416-4920; Mike Hillstrom, DNR Forest Health Specialist, Fitchburg, Michael.Hillstrom@wisconsin.gov or 608-513-7690; and Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665
Oak leafrollers feed on leaves and roll/fold them with strands of silk. Photo: Wisconsin DNR
An outbreak of oak leafroller moth, Archips semiferanus, has been observed in many parts of Wisconsin this year. Oak leafrollers are native, early-season defoliators. This year they have consumed and rolled up oak leaves, giving the tree crowns a thin, yellow appearance. Continue reading “Leafroller Charged With Severe Oak Defoliation”
By Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665
It seems to be a good year for insects, and several leaf beetles and leaf rollers have caused localized defoliation already this summer.
Willow leaf beetle larvae on a willow leaf. Photo: Wisconsin DNR
By Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665
Lecanium scale is popping up in a few areas of Oneida and Vilas counties. These scale insects insert their mouthparts into twigs and suck the sap of the tree. They release honeydew, which can be collected by ants or may coat leaves and anything located under infested trees (i.e., yard furniture or vehicles). Sooty mold can grow on that sticky material and turn things black, so homeowners may want to rinse off the honeydew from outdoor items on a regular basis.
The brown lumps on this stem are lecanium scales. Photo: Wisconsin DNR
By Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665
Spruce budworm is a native insect with periodic outbreaks that defoliate spruce and balsam fir in the Midwest. While these caterpillars have pupated and moths are already emerging to mate and lay eggs, spruce budworm defoliation is now becoming noticeable in northern and central Wisconsin as clipped needles stuck in caterpillar webbing turn rusty red.
Spruce budworm larvae had webbed together the new growth. Note some clipped needles in the webbing that will turn rusty red in color. Photo: Wisconsin DNR
Continue reading “Another Year Of Spruce Budworm Defoliation”
By Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665
The spiny oak sawfly feasts again. While defoliation by this insect is common in understory oaks, this year, lower branches of overstory oaks have also seen damage. All damage so far has been observed on red oaks. Previously we saw a widespread outbreak in 2005 with lesser reports of damage in 2007, 2016, 2017 and 2021.
Spiny oak sawfly larvae. Photo: Wisconsin DNR
Continue reading “Spiny Oak Sawfly And Red Oak: A One-Sided Love Story”
