SIOUX FALLS, S.D. (KELO) — The City of Sioux Falls is currently in the process of completing a multi-year endeavor to remove untreated Ash trees from public right-of-ways. The reason for this massive endeavor: the Emerald Ash Borer.

According to the City of Sioux Falls, this little creature is an exotic pest native to China, and has spread to 35 states after being detected in Michigan in 2002, killing more than 100 million Ash trees in the United States.

Kelby Mieras, Park Operations Manager for the City of Sioux Falls, says that the City began its removal project in 2018, preemptively removing Ash trees in City parks and properties, as well as those in the public right of way; ie. between your sidewalk and your curb.

Mieras says that if a tree in the right of way in front of your house is marked for removal, it will be painted with a blue ‘1’. The City will foot the bill for the removal of the tree, but the homeowner will have to take it from there; rejuvenating the spot where the tree had been, and purchasing a new tree if they would like to re-plant. The city has an approved list of ‘street trees’ to choose from.

According to South Dakota Agriculture and Natural Resources Forest Health Specialist John Ball, if left untreated, this insect will kill every Ash tree within an area in as little as 10 years. The City’s removal tactic is preventative, but there are other methods a tree lover can take to protect their mighty Ash.

The Emerald Ash Borer has been confirmed in South Dakota since 2018, but Ball says it’s likely that it’s been here for a few years longer than that. He says the only way to protect your Ash trees, is to treat them.

Ball says that currently Lincoln and Minnehaha are the only counties where treatment is being recommended, and when it comes to treatment, he says to call a professional.

“The first thing it entails is hiring someone,” says Ball. “This is not something that you can do yourself. If you have a tree bigger than say, four inches in diameter, the chemicals that are available to homeowners are really not sufficient, so you’re going to need to hire a commercial applicator.”

In terms of price, Ball says to expect some variation based upon demand, but he says a good rule of thumb for estimating is to measure the diameter of the tree at about chest height. He says the standard seems to be about $10/inch, so a tree with a 20 inch diameter will likely cost around $200 to treat.

One upside, is that you don’t need to treat your trees every year. According to Ball, you should treat your Ash every other year, and if you have more than one tree, you can stagger your treatments so that you’re doing half of the trees one year, and half the next year.

The good news, says Ball, is that in about 10 years most of the Ash trees in Sioux Falls, the untreated ones, will be gone, meaning the likelihood of infection will be lower. Due to this, you may then be able to treat your Ash less often, such as every three or four years instead of every two.

“Look at it as, you’re gonna hit it hard for about 10 years, every other year, and then you’ll be able to back off some.”

John Ball

If you choose to remove your trees, Ball recommends hiring an expert to avoid potential damage to yourself or your property. If you do opt for removal however, the timeframe is important. The City of Sioux Falls does not allow for removal or pruning of Ash trees between Memorial Day and Labor Day, as that is when the adult beetles are active and spreading, which could lead to artificial spread of the infestation.

Looking at the City’s Ash population, Mieras says that when the City began removal, there were round 22,000 Ash street trees in the community. He says that as of now they are sitting closer to 17,000, with the number decreasing each days as crews move through the neighborhoods.

The goal, says Mieras, is to cull the Ash population down to five-percent of the total street canopy. This process is part of a ten year plan, expected to reach completion in 2028.

When it comes to re-planting trees, both Ball and Mieras agree that diversity is key. “My planting advice for those going out this spring is look what your neighbors are planting, and plant something else,” says Ball.

Another thing they both agree on is this: Don’t plant Maple trees. “In the City of Sioux Falls,” says Ball, “for their street trees and their park trees, about a third of those trees are Ash — another third are Maples, and if we want to avoid having two people having a discussion like this 30 years from now on Maples; why did we plant so many Maples and some new pest arriving, it would be good to kind of look at other trees.”

Ball’s suggestion for a pest proof tree? Ginkgo. Ball says these trees have been around 300 million years, and that there is really no pest or disease that threatens them. They are also on the City’s list of recommended street trees.

If you have more questions about the Emerald Ash Borer, the City has an FAQ page, as well as more resources on the issue here.