Using EAB treated ash trees as mulch?

Sp. virginiana

New Member
Iowa city
Hello - One of my customers whose ash trees I have been treated has lost one in a storm recently. She is big into organic gardening and wants to know if the tree can be mulched and used in her garden, or if there is insecticide residue that would be a problem for her biome. The tree was treated with emamectin benzoate in spring of 2019, the medium dose. How long does this stuff persist in a tree? Can't it be present for 3 years or more in live tissue?



Well-Known Member
I cannot think of a circumstance in which it would be okay to apply mulch from that tree into a food consumption environment - whether organic or not. It may or may not be just fine, but emamectin benzoate is not rated for consumption. 3 years is the period over which it is effective in treating insects. I believe the label actually labels it as effective over 2 years. At year 4, there may still be emamectin benzoate present at a dose that does not affect most insects enough to kill them. At year 5, it might still be there but at a lower amount. The point being, you need to understand too much - the half-life, the mode of effect on insects and other animals, sublethal effects on insects and other animals, the constituents that it breaks down into and their effects on the garden ecosystem - at too high a level prior to jumping in. Emamectin benzoate has only been studied for its labeled applications and application rates.

Meanwhile, you can turf up a neighbor's tree that has not been treated, turn it into mulch, and apply that to the garden and get close to the same benefits of sustainability and organic agriculture.


Very stable member
Florida, USA
While she may not want to utilize the chips in her garden, they would likely be an excellent substrate for mycoremediation using a fungal associate which is saprophobic on ash. Fungi, in particular white rotters are able to deconstruct pesticide components. This way your client can keep the carbon on her site, while safely decontaminating it. While she may not wish to use the by product in her garden, she can find an out of the way corner to let it detox.

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