How To Protect Trees Against Emerald Ash Borer Using A DIY Solution

Emerald ash borers (Agrilus planipennis) are one of those invasive pests you should always kill on sight. Also known as EAB, they are responsible for the destruction of millions of ash trees in North America. Small trees often die within one to two years of infestation, whereas it takes about three to four years for large trees to die. Fortunately, there is an effective DIY solution that can save your ash trees. However, its success depends on detecting the infestation early. 

Early infestation opens the door to using systemic insecticide treatments through DIY techniques, such as the soil drench method using a simple solution. Yes, that is right, you don't need to call in an expert to save your ash tree. All you have to do is soak the soil around the base of the tree with systemic insecticides such as imidacloprid and dinotefuran. These treatments are absorbed by the tree roots and move through the tree's vascular system, killing EAB larvae. 

Imidacloprid works best for small trees when applied in the early spring. However, it may take several weeks to move through the tree and begin to take effect. Dinotefuran, on the other hand, produces much faster results and is often the best option if you miss the early spring treatment window.

For most homeowners, soil drenching using a DIY solution of systemic insecticides is often the best and simplest way to protect ash trees against EAB. It does not require any specialized tools and instead uses the tree's own root system to move the insecticide. To start, begin by measuring the circumference of the tree at about 4.5 feet height. Next, divide that number by pi, which will give you a value known as the diameter at breast height (DBH). This value is critical for calculating the right dosage of the EAB insecticide. 

Once you know the DBH value, it's time to prepare the DIY pesticide solution for treatment. Homeowners can easily find imidacloprid or dinotefuran at most garden centers under different brand names. Be sure to get a formulation that is specifically labeled for soil drench applications. Once you have the concentrate, mix 0.4 fluid ounces of concentrate per inch of DBH into 5 gallons of water in a bucket. 

Before applying, remove as much mulch and debris from around the base of the tree as you can. Then slowly pour your DIY insecticide solution evenly all over the root zone. Following that, pour another 5 gallons of plain water on the same area to help it soak down and improve dispersal. The treatment needs to be repeated every year for this to remain effective. But considering the low effort and low cost (less than $20 per tree), it should be a reasonable method.

EAB treatments work best while the tree still has some fight left in it. If the canopy is thinned by more than half, chances are the tree ash won't survive, even after treatment. So, if you are looking at numerous already dead large branches, bark stripping, and severe internal damage, you're better off removing the tree from the garden and planting something new. And, if the soil drench method with this DIY insecticide solution isn't working for you, you can look into trunk injections through a professional. 

You can go this way if the tree is of high value; however, make sure that you are aware of the downsides of using systemic pest control insecticides. Finally, landscape-scale strategies such as diversifying tree species or introducing parasitoid wasps can help stop the spread of EAB. Prevent the spread by removing and quarantining firewood. Through proper treatment and prevention, you can help your ash trees thrive.