Author: colleenrobinson

Prepare now – gypsy moth caterpillars return

Gypsy moth caterpillar with distinctive blue and red dots

Gypsy moth caterpillar with distinctive blue and red dots

This June, gypsy moth populations may rise to damaging levels in parts of Wisconsin. High numbers of gypsy moth caterpillars are a tremendous nuisance and can strip trees of their leaves. Combined with other stresses, such as drought or attacks by additional tree pests, this may kill the tree. The insect’s favorite food is oak leaves, but it will feed on many other tree species such as aspen, birch, crabapple and willow. You can take action to reduce the number of caterpillars that will feed on your trees, including placing sticky barrier bands on the susceptible tree species. Continue reading “Prepare now – gypsy moth caterpillars return”

Oak wilt and hickory mortality Forest Health Fact Sheets are available

The forest health program is in the process of updating some of our publications as Forest Health Fact Sheets. These publications offer biology, impact, prevention and management information about specific threats to forest health. Our new oak wilt fact sheet and hickory dieback and mortality fact sheet are currently available on the DNR’s forest health oak wilt and bark beetle webpages and will be available in the DNR’s online publications catalog  in the near future. Enjoy!

Written by: Mike Hillstrom, forest health specialist, Wisconsin Dells (Michael.Hillstrom@Wisconsin.gov), 715-459-1371.

Emerald ash borer new locations in Wisconsin

EAB quarantine map. Counties shaded in tan are quarantined for EAB, and include much of the southern half of Wisconsin, as well as other counties. Areas shaded in green are the townships and municipalities where EAB has actually been identified, and shows that not all counties that are quarantined are fully infested.

EAB quarantine map. Counties shaded in tan are quarantined for EAB, green areas are townships and municipalities where EAB has actually been identified.

Emerald ash borer (Agrilus planipennis) continues to be found in new areas. Wisconsin continues to track EAB at the municipality or township level; quarantine counties are shown in tan and infested areas are shown in green on the map.

If you know you have EAB, please contact us with that information so we can verify the infestation and update the maps. If your area:

  • is not shaded in green on the map please contact DNR or
  • is not shaded at all on the map please contact DATCP.

You can reach both agencies from the menu options when you call 1-800-462-2803.

New county quarantines

  • none

New finds in counties already quarantined

  • Brown County — village of Bellevue
  • Door County — village of Egg Harbor
  • Fond du Lac County — village of Rosendale and town of Springvale
  • Vernon County — town of Franklin

Written by: Linda Williams, forest health specialist, Green Bay, (Linda.Williams@wisconsin.gov), 920-662-5172.

Porcupine and squirrel damage

Porcupine damage on red pine trunk.

Porcupine damage to red pine.

Porcupines and squirrels damage trees by eating the bark. Sometimes they remove large areas of bark on branches as well as on the main stem. On sunny days the pale wood where the bark has been stripped off really stands out in the woods.

This type of feeding can remove enough bark to girdle the branches or the main stem, causing the tree to die from that point to the end of the branch. Branches that are not completely girdled will continue to grow and callus tissue will begin to grow over the wounds. If branches are nearly girdled, they may leaf out in the spring only to have the leaves suddenly wilt and die as hot weather hits because the tree can’t move enough water to keep the leaves alive. Continue reading “Porcupine and squirrel damage”

Slime molds and yeasts are bright and slimy

Several reports have recently come in of bright orange slime on trees or on mulch in Brown, Door and Shawano counties. Slime molds and yeasts can make bright colors, usually pink, orange, or yellow. Don’t panic – they don’t harm the tree. Often the orange, slimy areas on trees are associated with sapsucker wounds, where the tree has been bleeding sap on which microorganisms are growing. We see these most during the spring when the weather is moist, but once the weather warms the slime will dry up, leaving just a faint orange tinge to the tree where they were.

Sapsuckers wound trees and return to lick the sap that oozes from the wounds.

Sapsuckers wound trees and return to lick the sap that oozes from the wounds.

A stump is covered by orange slime. Slime molds and yeasts can be orange, pink, or yellow.

Slime molds and yeasts can be orange, pink, or yellow. Photo by: Gerald Vomastic

 

Written by: Linda Williams, forest health specialist, Green Bay, (Linda.Williams@wisconsin.gov), 920-662-5172.

Phomopsis galls on northern red oak

Phomopsis galls are woody, lumpy swellings on the branches and main stem of this northern red oak tree.

Northern red oak with many phomopsis galls on the branches and on the main stem.

Phomopsis galls are large, woody galls caused by a fungus and can be unsightly on the branches of trees (people often notice them in the winter when leaves are off). They occur in hickories, maples, oaks and a few other species. In northeastern Wisconsin, I find them most commonly on hickory, but in some areas northern red oaks can be heavily galled. Counties where I’ve seen these large galls on northern red oak include Oconto, Oneida, Shawano and Vilas. Continue reading “Phomopsis galls on northern red oak”

Eastern spruce dwarf mistletoe

Eastern spruce dwarf mistletoe (Arceuthobium pusillum), is a parasitic flowering plant that can be very damaging to black spruce, although it can also attack other spruces. Occasionally you’ll see it on other species growing amidst spruce such as tamarack, white pine, red pine, jack pine, or balsam fir. Continue reading “Eastern spruce dwarf mistletoe”

Forest tent caterpillar update

Forest tent caterpillars do not make web nests but may congregate and rest in groups on the bark.

Forest tent caterpillars do not make web nests but may congregate and rest in groups on the bark.

Caterpillars hatch from the eggs of a forest tent caterpillar egg mass.

Caterpillars hatch from the eggs of a forest tent caterpillar egg mass.

Forest tent caterpillars are hatching. Egg mass surveys were conducted in Iron, Ashland, Bayfield, Sawyer, Polk, Washburn, Douglas and Burnett counties, and no egg masses were observed. Surveys in Vilas, Oneida and Forest counties found very few egg masses.

Based on this information we expect low numbers and minimal defoliation again this year, but please let us know if you see forested areas with more significant defoliation.

Written by: Linda Williams, forest health specialist, Green Bay, (Linda.Williams@wisconsin.gov), 920-662-5172.