Article By: Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665
Have you seen small round holes in acorns? These holes are a sign of acorn weevil damage that can occur in all Wisconsin oak species.
Two acorns show exit holes of acorn weevils. / Photo Credit: Wisconsin DNR
Article By: Bill McNee, DNR Forest Health Specialist, Oshkosh
bill.mcnee@wisconsin.gov or 920-360-0942
In 2021, gypsy moth populations increased for a second consecutive summer due to favorable weather conditions. Populations typically increase with an average or mild winter, below average spring precipitation and above average May through June temperatures.
Regional variation in weather can result in significant differences in populations. If weather conditions are favorable again in 2022, the most noticeable increase in caterpillar numbers would likely occur in southern counties, where conditions were driest during this past spring and summer.
Populations experience the fastest growth rate and are first noticed on:
Gypsy moth egg masses found in Walworth County in fall 2021.
Photo Credit: Gypsy moth egg masses KMSU
Continue reading “Take Action! Look For Gypsy Moth Egg Masses”
Written By: Todd Lanigan, DNR Forest Health Specialist, Eau Claire, Todd.Lanigan@wisconsin.gov or 715-210-0150
As we head into September, fall webworm is starting to make its presence known. This native insect feeds on deciduous trees and shrubs and appears every year in yards and forests. Fall webworm forms loose webbing over branch tips and can completely cover a small tree with webbing. You will find both live and dead caterpillars, partially eaten leaves and frass (caterpillar poop) inside the webbing.
Fall webworm larvae inside webbing. Photo Credit: Wisconsin DNR
By Bill McNee, DNR Forest Health Specialist, Oshkosh, bill.mcnee@wisconsin.gov or 920-360-0942
Heterobasidion root disease (HRD), formerly known as annosum root rot, was recently found in Fond du Lac and Racine counties for the first time. Thinned pine stands were surveyed by DNR forestry staff in four eastern counties where the disease had not been previously found (Fond du Lac, Manitowoc, Racine and Winnebago counties).
Counties where Heterobasidion root disease (HRD) has been found as of August 2021 are shown in green.
Continue reading “Heterobasidion Root Disease (HRD) Found In Fond Du Lac And Racine Counties”
Plants that are pokey, viney or spread quickly across the landscape sometimes seem alarming when you discover them in your backyard or woods or when they’re spotted along the highway. Wild cucumber has all these characteristics but is not as ominous as it seems.
Wild cucumber (Echinocystis lobata) is a vine native across the U.S. and found throughout Wisconsin. It has maple-like star-shaped leaves and has pale greenish-white flowers from July through September. A single plant is self-fertile but can also be pollinated by bees, wasps and flies. It produces a pod-like fruit with spikes resembling a cucumber which is unsafe to eat. Each pod produces four seeds that fall to the ground when the pod is ripe. The pods may persist into the winter and become thin brown shells.
Star-shaped leaves, pale flowers, and cucumber fruit of wild cucumber. Photo: Bugwood
By Todd Lanigan, DNR Forest Health Specialist, Eau Claire, todd.lanigan@wisconsin.gov or 715-210-0150
This time of year, you may be noticing some large growths on oak leaves. You are either seeing oak apple gall and/or wool sower gall. These galls are formed by a small, stingless wasp, known as a Cynipid Wasp.
For the oak apple gall, when the female lays her egg, she injects a growth regulator that causes the leaf tissue to form around the egg. When the larvae begin to feed for the wool sower gall, this causes the gall to form. The galls in both cases protect the developing wasps from the elements and predators.
Oak apple galls are round and initially are green in color. Eventually, the gall turns brown as the wasp larva matures inside.
An oak apple gall
Written by: Linda Williams, DNR Forest Health Specialist, Woodruff, Linda.Williams@wisconsin.gov or 920-360-0665.
A frost/freeze on the night of May 28 strongly impacted our oaks in areas of central and northern Wisconsin. Some leaves were completely killed while others had portions of the leaf that were impacted. Those leaves with some dead spots have continued to expand and grow but the dead parts of the leaf are causing them to curl and pucker.
Oak leaves killed by the frost.
Continue reading “Oaks Hit Hard By Frost/Freeze Prior To Memorial Day”
By Bernie Williams, DNR Invasive Plant Specialist. Bernadette.Williams@wisconsin.gov or 608-444-6948.
Giant hogweed is a non-native, invasive plant that has gradually gained a foothold in the northeastern U.S. Once popular for its massive size and white umbrella-like flowers, it was introduced as an ornamental as early as 1917. Now known for its harmful blisters, it is recognized as a public health hazard and controlled wherever possible.
Characteristic purple blotches and white hairs on green stem of giant hogweed. Photo credit: Herkulesstaude_Fritz Geller-Grimm
By Andrea Diss Torrance, Invasive Insects Program Coordinator, andrea.disstorrance@wisconsin.gov, 608-516-2223
Gypsy moth has moved slowly across Wisconsin in the last 30 years since gaining a foothold in the counties along Lake Michigan. This month, the Animal and Plant Health Inspection Service and the Department of Agriculture, Trade and Consumer Protection (DATCP) determined that the invasive pest has become established in Eau Claire and Richland counties and have extended the quarantined area to include them. This is the first time since 2015 that new counties have been added to the quarantine. Fifty-two of Wisconsin’s 72 counties are now quarantined for gypsy moth.
Wisconsin Gypsy Moth Quarantined Counties
Continue reading “Eau Claire And Richland Counties Now Added To The Gypsy Moth Quarantine”
By Paul Cigan, DNR Forest Health Specialist
The Forest Health Team has just launched an interactive web map showing areas where seasonal oak harvesting opportunities and restrictions exist within the state. The map provides users with general geographical information on the presence and seasonality of oak wilt restrictions to support decisions concerning the application of the Oak Harvesting Guidelines [PDF] during timber management planning and establishment. As a highlight, areas that favor flexibility in the application of the seasonal harvesting restrictions — based on the nearest known detection of oak wilt — are displayed on the map. If you have any questions about this map, please contact your regional Forest Health specialist.
Oak Wilt Seasonal Harvesting Opportunities Web Map
