Expert arborist offers 2019 emerald ash borer outlook

May 30, 2019

This paid piece is sponsored by Aspen Arboriculture Solutions

By Sam Kezar, owner of Aspen Arboriculture Solutions

We will be heading into another year with emerald ash borer being in Sioux Falls. It actually will be the fifth year that the beetle has been in our city: We just didn’t find it until last year. Since the beetle was discovered in early May 2018, a lot of changes have been made that will affect how the beetle will spread and populate. This article reviews the emerald ash borer outlook for Sioux Falls. It will cover processes that affect the beetle and how they affect our management plans for 2019.

Emerald ash borer treatments

A lot of ash trees were treated or injected in 2018. The city recorded roughly 8,000 trees injected by licensed arborists in Sioux Falls. Many trees outside the city also were treated. This response by people to save their valuable ash trees is very good in combating emerald ash borer. Here are some reasons why:

  • Heard immunity
    • You’ve maybe heard the term before when talking about vaccines for certain diseases in people. The same kind of principle applies to the beetle as well. If several ash trees are treated in an area, the beetle population will have a hard time exploding as quickly as usual if only a few trees were treated. Treated trees kill the emerald ash borer larvae after the eggs hatch and enter the tree to feed. Adult females will fly from untreated trees to lay eggs on some treated trees, and those eggs will never make it to adults, thus slowing the increase in the amount of beetles out laying eggs.
    • The take-home is this: Start treating your valuable ash trees now not only to protect them from the eventual arrival of the beetle into your neighborhood, but also to slow the spread and loss of other non-treated ash throughout the city.
  • Infected trees treated
    • Many of the infected trees in the area where emerald ash borer was found in Sioux Falls were treated in 2018. This likely reduced the population to slow the spread.

Ash tree removals

Many people began removing lower-value ash trees. The city also started a very aggressive removal program of lower-value ash trees along city streets. By removing ash trees from the landscape, it will slow the spread of the emerald ash borer by providing less food for the larvae to feed and populate.

One very beneficial city ordinance that was put in place to reduce emerald ash borer movement is the ban on pruning or removing ash trees between Memorial Day and Labor Day. This will greatly reduce the chances of spreading emerald ash borer around the area by reducing wood movement that may be full of larvae or adult beetles.

Avoid waiting for ash trees you don’t intend on saving to die before removing them. You will have a few years before they likely start to die. However, ash trees become very brittle when succumbing to emerald ash borer. So waiting until they start to die or die completely will increase the danger of removing the trees and increase your removal costs.

Polar vortex

This particular winter cold snap got a lot of news coverage. I saw a bunch of news articles giving false hope that the cold weather will slow down or kill a bunch of emerald ash larvae. Here is the short answer: No. Don’t get your hopes up. It got cold in Sioux Falls those few days but not nearly long enough nor cold enough to do any sort of benefit beyond an average year in the grand scale of beetle populations. To read more, here is a link to another article I wrote on the subject.

Outlook for 2019

The emerald ash borer outlook for 2019 is good. Not much is going to happen yet with emerald ash borer and ash trees. You won’t notice untreated ash trees dying or declining yet from the current emerald ash borer find.

We did find one new populations in  a different part of the city near 37th and Minnesota. According to the Department of Agriculture: “Satellite infestations, ones not connected with the main body, are a common feature of emerald ash borer infestations in a community. These often appear several miles or more away from the core and usually begin with only a few trees. The discovery of a satellite infestation is not a cause for alarm but more a reminder of the need for action. “

Currently, the Sioux Falls emerald ash borer population is projected to explode and start killing large amounts of ash trees starting in 2022. If treatments and removals continue on a good pace, it could push that out a year or two more. But it likely won’t be too much further out than that because we’re already finding satellite emerald ash borer populations.

Here are some important things to keep in mind for dealing with emerald ash borer in 2019:

  • Treat your high-value ash trees now. I strongly discourage waiting too much longer past 2019-20.
  • Plan to remove your ash you don’t plan on treating before they become infested. As mentioned above, you will have a few years before this likely happens.
  • Just because you don’t see dying ash trees, it doesn’t mean the issue isn’t getting worse. This is a long-term battle. It will take three or four more years before it becomes very noticeable.

Call or text to 605-759-6020, email, or fill out the consultation request form  at

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Expert arborist offers 2019 emerald ash borer outlook

Just because you might not be hearing much about emerald ash borer doesn’t mean it’s gone away. Far from it: Here’s the 2019 outlook and why you need to prepare now as conditions are going to start worsening.

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