A dense patch of Japanese stilt grass growing within a forest. / Photo Credit: Wisconsin DNR
By Carter Hellenbrand, Invasive Plant Field Specialist, Fitchburg;
Carter.Hellenbrand@Wisconsin.gov
Note: This is the fourth installment in the Forest Health News “Invasives Spotlight” series, a monthly series of Forest Health News articles.
What has stilts, is green in the summer and reddish-purple in the fall? Japanese stilt grass!
Japanese beetles defoliating a basswood leaf. / Photo Credit: Wisconsin DNR
By Linda Williams, Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov, 920-360-0665
The Japanese beetle (Popillia japonica) is an invasive insect that feeds on many plant species. The adult beetles “skeletonize” leaves by eating the material between the veins.
Adult Japanese beetles feed on the flowers and leaves of more than 300 plant species, including trees, shrubs and herbaceous plants. Forest trees can be defoliated, with open-grown or edge trees suffering the highest defoliation rates.
Continue reading “Japanese Beetle Populations Still Building In The North”
Tamarack trees showing the effect of larch casebearer defoliation. / Photo Credit: Wisconsin DNR
By Linda Williams, Forest Health Specialist, Woodruff;
Linda.Williams@wisconsin.gov, 920-360-0665
Earlier this spring, scattered areas of tamarack in North Central and Northeastern Wisconsin showed tan or light brown foliage. Sometimes that is due to frost, but this year it was the work of an insect called larch casebearer.
As the foliage started to expand this spring, the larch casebearer became active and began to feed. The tiny caterpillars mine out the needles of tamarack and use them as “cases” to protect themselves, thus their name.
Continue reading “Tamaracks Busy Refoliating After Larch Casebearer Defoliation”
By Bill McNee, Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov
A spongy moth caterpillar feeds on a leaf. / Photo Credit: Wisconsin DNR
Property owners are encouraged to monitor their trees for spongy moth larvae and damage this summer to determine whether control measures are needed.
Property owners who have oak, birch, crabapple, aspen, willow and linden (basswood) trees should be particularly watchful because the caterpillars of this invasive insect prefer these species.
However, they will feed on many other kinds of trees and shrubs.
Continue reading “Watch For Spongy Moth Caterpillars And Tree Damage This Summer”
By Linda Williams, Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov, 920-360-0665
Red turpentine beetle and pine root collar weevil both attack pines near ground level. So, how can you identify them and differentiate the damage?
If you prefer the abbreviated version, check out the table below. For more details, read further and be sure to check out the photos.
| Pine Root Collar Weevil | Red Turpentine Beetle | |
| Hosts | Pines | Pines, tamarack, spruce, fir
|
| Tree size | Younger pines (generally less than 8 inches diameter at breast height). | Larger trees (generally greater than 8 inches diameter at breast height)
|
| Location of damage | Ground level and below | Lower 1-3 feet of the trunk
|
| Signs and symptoms | Trees leaning heavily or broken over at the base. Black, pitchy soil at base of tree. Black, pitchy, sunken area at base of tree. | Scattered trees in a stand decline and die. Pitch tubes near base of tree
|
| Prevention | Maintain stocking and crown closure to prevent grass and weeds around the base of trees. | Keep trees healthy
|
| Management | Remove grass and weeds from base of trees. Prune lower branches to increase air flow. Insecticides may be an option. | Salvage |
Damage at the base of young red pine, by pine root collar weevil can weaken it and trees with green needles can suddenly break over. / Photo Credit: Wisconsin DNR
Pine root collar weevil prefers younger pine stands that are open, with grasses or weeds near the bases of the trees to give the insects additional protection. Pine root collar weevil will attack red, jack, scotch and Austrian pine, but rarely white pine.
Pine root collar weevil damages roots and creates a weakened area of the tree at ground level. Damaged trees can break over at ground level if damage is on the trunk or may just lean heavily if roots are damaged and can no longer keep the tree upright.
To look for pine root collar weevil pull the weeds, duff and soil away from the base of the tree and away from the major roots. Infested trees will have black pitch-soaked soil around the base. Removing the bark from the root collar area and from the major roots, will show boring damage from pine root collar larvae just under the bark. The base of the tree may be slightly sunken where weevil larvae have been feeding under the bark.
Management options depend on the age and stocking of the stand when you notice the infestation. Planting at the proper depth and maintaining good crown closure to minimize the amount of grass and weeds around the base of trees can help prevent infestation. If you already have an infestation, eliminating weeds and grass around the base of trees and/or pruning lower branches can increase air flow to dry out the base of the trees and make them less attractive to the weevils.
Looking closely at the base of a tree being attacked by pine root collar weevil shows blackened pitchy dirt around the base of the tree. / Photo Credit: Wisconsin DNR
Pitch blobs near the base of a red pine indicate attack by red turpentine beetle. / Photo Credit: Wisconsin DNR
Red turpentine beetles generally prefer pine trees that are pole-sized and larger. They attack the lower 2-3 feet of the trunk of pines that are under stress, but can also attack stressed tamarack, spruce and fir. The original stressors could be abiotic, such as drought, flooding or fire, could be due to stress from thinning, or from trees being planted too deep or off-site.
Look for pitch tubes around the base of the tree. Adult beetles bore into the bark to lay eggs under the bark, and the tree will start to exude pitch, which the beetles push out to create a blob of pitch called a pitch tube. Pitch tubes will last for many months to years and are a noticeable clue indicating attack.
Larvae feed under the bark. The damage they do can girdle areas, which puts additional stress on the tree. If multiple pitch tubes are noticed at the base of a tree, the damage could be severe enough that Ips bark beetles could attack the tree and kill it.
Red turpentine beetle can also carry the spores of Leptographium root disease and, when introduced to a red pine, the disease can begin to spread through the roots and create expanding pockets of mortality, referred to as Red Pine Pocket Decline And Mortality.
Maintaining tree health is the best way to prevent attack by red turpentine beetles. When stress is severe, and attacks are numerous, salvage of trees may be necessary.
A putty knife, plastic knife or similar object can be used to gently scrape spongy moth egg masses into a cup of soapy water. The water can be discarded after two days. / Photo Credit: Wisconsin DNR
By Bill McNee, DNR Forest Health Specialist, Oshkosh
Bill.McNee@wisconsin.gov
The Wisconsin Department of Natural Resources (DNR) encourages property owners to examine their trees for spongy moth egg masses and determine whether control measures are needed this spring.
Property owners who have oak, birch, crabapple, aspen, willow and linden (basswood) trees should be particularly watchful because the caterpillars of this invasive insect prefer these species. However, they will feed on many other kinds of trees and shrubs.
Continue reading “Look For Spongy Moth Egg Masses And Take Action”
This northern red oak has many large Phomopsis galls. / Photo Credit: Wisconsin DNR
By Linda Williams, DNR Forest Health Specialist
Linda.Williams@wisconsin.gov or 920-360-0665
Winter is a great time to admire the structure of trees. When they are without leaves, you can see how the branches are arranged, how large or small the branches are, and if they are fairly straight or contorted. You might also notice some swellings or growths on those branches.
Two types that can really make a statement are Phomopsis and black knot.
Continue reading “Phomopsis, Black Knot Easily Found In Winter”
A hemlock borer larva inside channels in a hemlock tree. / Photo Credit: Steven Katovich, Bugwood.org
By Linda Williams, DNR Forest Health Specialist, Woodruff
Linda.Williams@wisconsin.gov or 920-360-0665
Woodpeckers are often the first to know that a hemlock tree is being attacked by hemlock borer.
Woodpeckers will flake off the outer layers of bark to get at the tasty hemlock borer larvae under the bark, leaving the tree with a reddish hue that, once you’ve seen it, is unmistakable. The woodpecker damage quickly makes it obvious that the tree was fully infested from top to bottom by hemlock borer.
Tim Shively, the Wisconsin Department of Natural Resources Forest Health specialist for the West Central zone. / Photo Credit: Wisconsin DNR
By Art Kabelowsky, DNR Outreach and Communications, Fitchburg
Arthur.Kabelowsky@wisconsin.gov or 608-335-0167
Tim Shively, the Wisconsin Department of Natural Resources (DNR) Forest Health specialist for West Central Wisconsin, will give a presentation titled “Forest Health for Everyone” at a meeting of the Juneau County Men’s Shed at 10 a.m. Tuesday, Jan. 27, in Mauston.
The event is part of a program put on by the Aging and Disability Resource Center of Eagle Country, and will take place at W4890 County Hwy. N, Mauston. It is open to the public. Continue reading “Shively, McNee To Make Public Appearances”
By Tim Shively, DNR Forest Health Specialist
Timothy.Shively@wisconsin.gov or 608-772-6974
A white pine blister rust canker as seen on a young white pine tree. / Photo Credit: Wisconsin DNR
Eastern white pine (Pinus strobus) has historically held great ecological, cultural and economic value throughout Wisconsin, a tradition which continues today. For more than 100 years, however, it has been threatened by a non-native, invasive fungal pathogen called Cronartium ribicola, or white pine blister rust (WPBR).
Continue reading “White Pine Blister Rust Can Devastate Young Stands”
