Adult emerald ash borer

The emerald ash borer (EAB), a non-native invasive beetle, was discovered on Riveredge property in January, 2009. This did not come as a big surprise since the first documented cases of EAB in Wisconsin were found less than a mile away in Newburg in August, 2008. Authorities believe that, based on the extent of that infestation, the EAB has been in the area since at least 2004.  Ash trees currently make up approximately 20% of the RNC forest canopy, but since 2008 they have been subjected to the EAB and many have, or are starting, to die off.  The hardest hit area on the RNC property is a half-mile stretch along the Milwaukee River and one of its tributaries, encompassing approximately 6 acres of riparian and river island habitat.

Aerial photography of RNC property along Milwaukee River. Dead ash (grey in color) can be seen in large quantities along the river.

Aerial photography of RNC property along Milwaukee River. Dead ash (grey in color) can be seen in large quantities along the river.

Want to learn how to identify EAB?  Check out this document by Gary L. Parsons (Department of Entomology, Michigan State University).

Emerald Ash Borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae): A guide to identification and comparison to similar species

Research at Riveredge

Biocontrol/Parasitic Wasps Release Project

In the summer of 2011 Dr. Ken Raffa and Todd Johnson, from UW-Madison, released 5400 tiny parasitic wasps at Riveredge to feed on EAB larvae & eggs. Their hope was that the wasps would survive and multiply enough to eventually eliminate EAB from this area sometime in the future.

In January, 2013 Dr. Raffa & Todd returned to Riveredge to determine if the wasps are successfully reproducing. To do this they harvested four EAB infested ash trees from the parasitic wasp release site in Mayhew Woods. The felled trees were cut into three foot sections and placed in sealed rearing tubes. The rearing tubes (~100) were stored in the Wallner barn and monitored last summer for emerging wasp parasitoids by volunteer, Chuck Ritzenthaler.

Todd Johnson releasing parasitic wasps at Riveredge.

Todd Johnson releasing parasitic wasps at Riveredge.

On November 7, 2013 Todd Johnson informed us that one of the biocontrol agents successfully emerged and were found in the samples Chuck collected from the rearing tubes. A total of 38 females and 2 male Tetrastichus planipennisi (parasitic wasps) emerged over four dates from two logs from the same tree. Juli Gould, from the USDA, told Todd that “this shows that the parasitoids have actually established themselves at Riveredge, since they are not only reproducing in the field but also have gone through several summer/winter cycles.” With any luck these wasps will continue to thrive and help control EAB in this area.

At the end of this five year study (2016), USDA guidelines call for a total of 96 of our ash trees (48 in the control and 48 in the release plots) to be harvested and examined for wasp parasitoids. This may not be feasible given the location of these trees at Riveredge but the logistics will be reevaluated at the time.

EAB Detection Methods

Riveredge has become a showcase for demonstrating to other property owners the various methods used to detect and deal with the EAB. During thesummer of 2009, the Department of Agriculture, Trade and Consumer Protection (DATCP) placed purple traps of various sizes

EAB traps

EAB traps

and shapes on the property. The traps were made out of thin, corrugated, purple plastic coated with different sticky, non-toxic substances used to lure the ash borers to them. Similar traps were placed in other parts of the county and state. If you see a trap in your area it doesn’t mean that EAB are in your neighborhood. The traps are simply used to determine if EAB are present and if so in what quantity.

A study initiated by Jane Cummings Carlson, forest health coordinator for the WDNR, in June, 2009 involved creating five EAB “sinks” near our west entrance. Each sink consisted of a cluster of one control and three girdled ash trees. The clusters were located within 50 feet of an existing trail to allow easy access and removal. The dying, girdled trees emitted a scent which drew in emerald ash borers that were looking for brood trees. These girdled trees were cut down and hauled out using Percheron horses on February 20, 2010 during a small-scale logging demonstration. Samples from each of the tree clusters were examined by DNR experts to determine their degree of the infestation. Over 2,000 board feet of ash lumber was cut here that day.

Logging Demo & Ash Tree Management

On December 8. 2013 Luke Saunders and Anna Healy from Adaptive Restoration demonstrated small-scale methods for harvesting logs, while

Luke Saunders and his draft horse removing EAB infested ash.

Luke Saunders and his draft horse removing EAB infested ash.

felling ash trees infested with emerald ash borer (EAB). The loggers showed how to drop trees, then, using rare Sulffolk Punch draft horses, skidded them out with little or no damage to the environment. The program was open to the public and was attended by horse lovers and home owners with EAB issues. It was the culmination of a three week long logging operation during which Luke & his partner dropped 97 ash trees at Riveredge. These infested ash trees were within a few feet of the trails near our west parking lot. The logs amount to 3,540 board feet of lumber and around five cords of pulpwood/firewood.  Jim Bednar, from Algoma Lumber, will purchasing the downed logs.

Back in 2011, while working for the WDNR, Luke surveyed our trails and determined that there are over 1,850 ash within 50 feet of our trails. Given this fact the 2013 demonstration was just the beginning of a multi-year effort to remove trees that  potentially pose a threat to Riveredge visitors or buildings.

Insecticide Treatments

Over the past few years a number of ongoing experiments have been conducted at Riveredge to help slow the spread of EAB. Dr. Chris Williamson and graduate students from UW-Madison started treating 140 of our ash trees in the summer of 2009. They’ve been trying to determine which type of insecticide is most effective in deterring EAB on different species, sizes and age classes of ash.

The majority of our untreated ash trees are now dead or dying. Many of the treated trees, however, are still alive and doing well. Insecticide treatments ended in the summer of 2013. Conclusions from the study will be shared with the public in a UW-Extension bulletin that will be published in the spring of 2014. Williamson has graciously offered to advise Riveredge regarding how to treat the few remaining live ash in his study area.