Urban Forestry News

New, customizable resource shows the value of trees

Money doesn’t grow on trees, or does it?

People know the many benefits that trees can provide – clean our air, beautify our communities, reduce stormwater runoff, and decrease noise pollution – but did you know trees also save you money?  With technology from i-Tree you can calculate how much your trees are saving you.  Now, with a new resource from the USDA Forest Service Urban Natural Resources Institute (UNRI), you can let others know exactly how much your trees are saving you. Continue reading “New, customizable resource shows the value of trees”

EAB found in third Douglas County township

By Paul Cigan, forest health specialist, Hayward, Paul.Cigan@wisconsin.gov, 715-416-4920

Emerald ash borer (EAB) has been confirmed in Highland Township in Douglas County, making it the third township with a known EAB infestation in this county. Utility line professionals reported white ash with heavy woodpecker damage, or “flecking,” that was later confirmed to be an EAB infestation. The extent of damage to the tree suggests that the infestation is approximately 4 years old. Surrounding black ash do not display signs or symptoms of EAB. Nevertheless, based on EAB’s natural rate of spread, there is likely to be a low-density population for about 15 miles around the infested tree in all directions. The nearest previous EAB detection, made in the Town of Amnicon in 2017, is located 23 miles away. Firewood transport is the most likely source of this latest outlying introduction.

Known EAB detections as of April 25, 2019.

Known EAB detections as of April 25, 2019.

Forest managers working with ash should become familiar with the revised EAB Silviculture Guidelines, and landowners and managers in northern counties are encouraged to report EAB suspect trees to their regional forest health specialist.

EAB-infested white ash with heavy woodpecker flecking and dead epicormic sprouts.

EAB-infested white ash with heavy woodpecker flecking and dead epicormic sprouts.

Dense EAB larval galleries on the wood surface of infested white ash.

Dense EAB larval galleries on the wood surface of infested white ash.

Revised EAB insecticide guide now available

By Bill McNee, forest health specialist, Oshkosh, Bill.McNee@wisconsin.gov, 920-360-0942

Title page of revised insecticide guide.The North Central Integrated Pest Management Center has released the third edition of its widely distributed guide, “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer.” This updated document addresses frequently asked questions and shares new information about insecticide options that are not covered in the guide’s previous edition from 2014. To review the most current recommendations and study results regarding insecticide use for EAB, download the report here.

Make trees mean more

Spring is upon us and that means the tree planting season is too. Trees are vital to our environments; they provide individuals and communities with clean air, clean water, reduced cooling costs, safer neighborhoods, and a place to play and gather. But trees provide much more than that, they can help show how much we care for others, a beautiful living reminder of the legacy of a person. Arbor Day is this month, and it is the perfect time to plant a tree and illustrate our feelings for others. Continue reading “Make trees mean more”

DNR awards second round of urban forestry grants

The DNR Urban Forestry Grant program awarded over $70,000 to 3 Wisconsin communities and 1 nonprofit organization for urban forestry projects during our 2019 second round of funding. In order to ensure a pool of catastrophic storm funds throughout the year we award grants in two rounds rather than awarding all funds in December. The communities who received grants in the spring include City of Franklin, City of Milton, City of Oshkosh, and Riveredge Nature Center. Continue reading “DNR awards second round of urban forestry grants”

Protect oaks from oak wilt by waiting to prune

By Don Kissinger, urban forester, 715-348-5746, don.kissinger@wisconsin.gov and Paul Cigan, forest health specialist, 715-416-4920, paul.cigan@wisconsin.gov

To protect oak trees from the often-fatal oak wilt disease, don’t prune, cut or injure oak trees from April through July. 

Pruning and cutting oaks in spring and early summer leaves them vulnerable to oak wilt, which rapidly kills trees in the red oak group and weakens those in the white oak group. Any damage during this time, including broken branches caused by storms, exposes living tree tissue beneath the bark and provides an opportunity for the oak wilt fungus to infect the tree.

Sap-feeding beetles introduce the disease by carrying oak wilt spores from infected trees or firewood to fresh wounds. Healthy oaks can become infected in as little as 15 minutes after the creation of a wound. 

Sap-feeding beetle on diseased oak tree in Sawyer County.

Sap-feeding beetle on diseased oak tree in Sawyer County.

The trees most likely to die from oak wilt infection are in the red oak group, including northern pin oak, northern red oak, red oak and black oak. The white oak group is more likely to survive infection and includes bur oak, swamp white oak, white oak and English oak.

Tree paint or wound dressing is not normally recommended on pruned or wounded surfaces, but for damaged oaks an immediate light application of these products may be the only defense against oak wilt infection from April through July.

Pruning in spring can be damaging to any deciduous tree because their energy reserves are low as they produce new buds and leaves following the winter months. In general, the best time to prune is in winter when trees are dormant. 

As of January 31, oak wilt has been found in all Wisconsin counties except Ashland, Iron, Forest, Taylor, Door, Kewaunee, Calumet and Manitowoc counties. Several of these counties contain the highest abundance of healthy and productive oak forests in the state. Taking recommended precautions will help keep them that way for years to come.

Oak wilt and other diseases move easily on or in firewood logs year-round, so keeping firewood local, or purchasing Wisconsin-certified firewood, is another important component of protecting trees and keeping forests healthy. Visit the DNR firewood page for more information and a directory of certified firewood vendors.

More information, including a recently released oak wilt video, is available at the DNR oak wilt page. Additional information about proper pruning techniques is available from community foresters or through DNR resources such as this tree pruning poster

Treat your valuable ash trees against EAB

By Bill McNee, DNR forest health specialist, Oshkosh, bill.mcnee@wisconsin.gov, 920-360-0942

Spring is the best time to evaluate valuable ash trees and determine if they should be treated to protect them from emerald ash borer (EAB). Emerald ash borer is currently the most damaging threat to trees in the state, killing more than 99 percent of the ash trees it infests.

Insecticide treatments to prevent EAB infestation are usually applied between mid-April and mid-May, so it is important to start planning now. The first thing homeowners should do is check their ash trees for signs of infestation. Woodpecker damage is easy to see this time of year and is often the earliest visible sign of EAB. Photos of other signs and symptoms can be found on the DNR EAB website.

Ash trees with woodpecker "flecking" indicate EAB infestation.

Signs of EAB infestation include woodpecker damage where the birds pick away ash tree bark to feed on larvae.

Emerald ash borer has become so widespread that homeowners should consider treating valuable ash trees no matter where they are in Wisconsin. The highest risk of EAB infestation is within 15 miles of a known infestation, but it is widely believed that there are additional, undetected EAB infestations throughout the state. To see a map of known EAB infestations, visit the Wisconsin EAB website.

While the best time to treat ash trees is before they are infested, treatments of infested trees can still be successful if done while EAB populations within the tree are low or moderate. Some ash trees may be too heavily infested to save or they may have other problems that make them poor candidates for treatment.

Trunk injection treatment for EAB. Credit: Matthew Karst.

Trunk injection treatment to protect against EAB. Credit: Matthew Karst.

You should consider several factors when deciding whether to treat your ash trees. Insecticide treatments can be costly, but the investment may be worthwhile if you consider the many benefits that healthy yard trees provide, including higher property values, better air quality, shading and cooling for homes and more. Removing and replacing your ash trees is another option and may be the best choice for heavily infested and lower value trees. For trees that you decide are worth saving, however, the cost to treat may still be less than removing and replacing them with other species. This factsheet from UW-Extension can help you decide whether a tree is worth treating.

If you decide to treat, or if you want to discuss treatment options with a professional, call a certified arborist or search online and in phone books for other businesses. Check the credentials and insecticide applicator certification of any business before hiring them to treat your ash trees.

Treatments are not economically practical for ash found in woodlots. Any questions about woodlot management should be directed to a professional forester.

Despite the cold winter temperatures in late January and early February, don’t postpone treatment of ash trees. Weather data and collection of overwintering EAB larvae at two sites in Waukesha County predict high insect survival rates in most of the state. Female beetles can lay up to 200 eggs, so EAB populations will quickly rebound from any mortality that occurred due to cold weather.

More information about EAB and management options can be found through the Wisconsin EAB website.