1,000 Windsor ash trees may have survived emerald ash borer blight of early 2000s

An inventory of city trees has led to the discovery of hundreds of ash trees — a species the city thought was completely wiped out during an emerald ash borer infestation which began in the 2000s.

The inventory began in June and about 500 ash trees have been found to be still standing.

"EAB went through the region in 2003, 2004," said city forestry analyst Gaspar Horvath. "At that time, the inventory tells us we had something like 7,000 large, mature ash trees. Most of those died."

About the emerald ash borer

  • Exotic beetle first discovered near Detroit in 2002.

  • Larvae feed on inner bark of ash trees, disrupting the tree's ability to transport nutrients.

  • Likely arrived in the United States via solid wood packing material carried in cargo ships or planes from Asia.

  • As of fall 2018, the ash borer is found in 35 states and in five provinces.

According to Forests Ontario, the emerald ash borer's spread cannot be stopped — as beetles travel up to 10 kilometres each year. Since 2002, millions of trees in the Great Lakes region have been destroyed by the invasive species.

"We essentially lost all the ash trees," said Horvath. "Or so we had thought."

There are about 100,000 trees in Windsor, something Horvath called a "highly valuable asset."

In order to protect that asset, the city conducts an inventory. By the time the inventory is complete, Horvath estimated there could be about 1,000 ash trees in Windsor.


The city has told the Invasive Species Centre, based in Sault St. Marie, that there are still ash trees in the city. Horvath said officials from the Centre may come to assess how these trees survived.

So far, the east end of the city has been inventoried — but Horvath said he assumes the ash trees are evenly spread across the city.