How Should I Plan for Emerald Ash Borer in South Dakota?

It is just a matter of time. Emerald ash borer (Agrilis planipennis) will make it to South Dakota and into Sioux Falls. The real question we need to worry about is, “When?” As of right now (February 2018), the beetle is not and has not been found in South Dakota.

Ever since EAB has been found and the word has gotten out, I have been asked by concerned tree owners what they need to do to save their trees. Unfortunately, there is a lot of miss-information out there and people (companies) are taking advantage of that. So first off, lets go over the facts: (You fact check this and learn more HERE or HERE).

1. Emerald ash borer (EAB) will kill any tree in the ash genus (Fraxinus). For South Dakota that would include green ash (F. pennsylvanica), black ash (F. nigra), white ash (F. americana). It will not affect mountain ash (Sorbus acuparia) as it is not a true ash (closer to an apple tree really).

2. Your tree will not immediately succumb to EAB (e.g. days or months). Emerald ash borer is an insect. The larvae feed on the tree under the bark. A healthy tree can live up to 4-6 years before fully dying from the attack. Most trees will steadily decline in health over the course of a few years. Generally, a tree will be unable to be saved after 1-2 years of attack (depending on health) when the insect population is at its highest and established within an area.

3. Treatments are available to control EAB and they are very effective if done correctly. However, the current scientific protocols are to only treat trees that are within 15 miles of a confirmed EAB location.

4. To keep an ash tree alive once EAB is in an area, the treatments will have to be done indefinitely. Treatment timing, application method, and chemical usage will vary depending on tree health, insect population, and proximity to your tree, but you will not be able to stop without the threat of the tree being attacked by EAB.

5. The adult beetle is a very poor flyer. So movement of the beetle more than a mile or so a year will be by human moment.

Alright, so that’s the quick run down and basic info you need in order to start planning. Now that you know that, here are the questions you need to ask yourself on How to Prepare for EAB:

1. How many ash trees do I have and which ones are valuable to me? Taking an inventory of your ash trees is the best place to start. This will help you determine future costs. If you can’t indentify an ash from boxeler or elm, then investing in having someone come out to identify your trees for you would be a good start.

2. Which trees are in good enough health or condition to save? Another big issue to look at is the structural condition and overall health of your ash trees. If some of your trees have structural defects, or other issues that may affect health in the near future, then its probably prudent not to waste any effort on saving those trees.

3. How long do I plan on treating the tree(s) I want to save? In most situation you may only treat some trees for a few years or more to ‘buy’ time until replanted trees can establish and starting filling in the void that will be left. But whatever your situation, you should have a long term plan for all the ash trees you own.

Once you have those questions answered, its time to develope a long term plan:

1. Create a plan to start removing your lowest value ash first. The sooner you start, the less you will lose once the beetle arrives and trees start dying. This will also help spread out your costs over time. Even though it will take a few years for the trees to die once attacked, the more dead the ash become the more brittle and dangerous to remove they become. This will increase removal costs dramatically. When choosing replacement trees, choose a variety of species.

2. Put effort into getting the ash you plan on keeping as healthy as possible. You obviously don’t want to sink in a bunch of money into a tree you will eventually have to pay to keep alive, but there are plenty of techniques in keeping trees healthy that don’t require professional help (see this article on tree maintenance).

3. Have a treatment plan in place for when the news hits. The biggest part to take away from all of this is DO NOT start treating your trees until the beetle is at least within 15 miles of your trees. Even then, I would caution against jumping the gun. All your doing is wasting money by preventatively treating before the beetle has an oportunity to feed on your trees. When a population of EAB starts to establish in an area, it usually takes 5 years or more for the population to explode and start causing widespread damage. So in the beginning, there is no need to panik. There is plenty of time to develope a plan and or follow the plan you have decided on.

The facts of emerald ash borer are well known with plenty of valuable and accurate information available online (Government or Univeristy sites). It will be up to you to educate yourself on the facts for when the beetle arrives in South Dakota. I have outlined a few of the main considerations when starting to plan for EAB, but the main consideration is that you do what you feel is best for your trees, landscape, and budget.