RENO, Nev. (AP) — The lingering effects of three consecutive years of dry winters coupled with a voracious beetle are killing northern Nevada's birch trees at epidemic levels and could wipe them out entirely, local arborists said.
The European white birch trees not immediately affected by the drought face another predator: A widespread infestation of the bronze birch borer, a beetle that can kill the tree in two or three years.
"I think the days of the birches in the valley are numbered," Reno city arborist Jim Ross told the Reno Gazette-Journal.
In Washoe County, about 60 percent to 70 percent of all birches have died during the past seven years, said Lynda Nelson, Washoe County horticulturist.
Although the majority of birches are on private property, about 500 county- and city-owned birches are left in the area.
Ross said the city of Reno stopped planting birches at least 15 years ago for practical reasons.
"Water is so precious here, it makes no sense to plant a tree that needs to be watered its entire life span," Ross said. "They would never survive here in the desert without man power."
In Carson City, the situation is just as bad, contract arborist Molly Sinnott said.
"We didn't have a problem until about two years ago, when we noticed a lot of mortality," she said. "In one block, there's four houses in a row with dead birches in their front yard."
Northern Nevada's hot desert temperatures and wind do not make an ideal environment for birch trees, which need cool moist weather and plenty of water, Ross said.
Nelson agreed. She said the county stopped planting birches about seven years ago and recommended that residents also cease cultivating the trees.
"We might need to adjust our thinking and plant trees and plants that are more sustainable under drought conditions, so that when we do go through these cycles were not devastated," Nelson said.
She said her office has been busy with calls from people wondering why their birch trees are dying and how to take care of them.
"The average person may not realize the drought affect, but if you're in the business, you recognize the lack of precipitation and it's much more apparent now," Nelson said.
Birches weakened by the lack of precipitation are more susceptible to borer infestation.
"If a person has a low immune resistance, he'll get the flu. It's the same with trees," Nelson said.
The birch beetle, which can grow as long as 2 inches, kills trees by laying eggs on the tree bark. These hatch into larvae that seep into the tree, interrupting the flow of sap. The life cycle of the beetle from egg to borer is about one year, and in two or three generations, the tree will die.
— Arizona Daily Sun