Tree services
Should I treat or remove my ash tree because of emerald ash borer?
A common question, answered by the MadisonWI.com editors · November 9, 2026
1 answer
From MadisonWI.com
UW–Madison Extension's homeowner guide says to start by weighing the tree's location, value and health against the cost of treating it every year. Insecticide treatments aren't suggested for ash trees with more than 50% canopy thinning; those trees should be removed, following local guidelines. Treatment works significantly better on trees with less than 50% thinning, and it should start before the tree is infested. Treatments must be repeated each year to keep the tree healthy. Homeowner products are mostly imidacloprid soil drenches, applied mid-April to mid-May, and they're meant for a few small trees, up to about 15 inches in trunk diameter at breast height. For larger trees, the guide says a professional may be the better option; certified arborists and pesticide applicators can use some products that aren't available to homeowners. Source: UW–Madison Division of Extension, Homeowner Guide to Emerald Ash Borer Insecticide Treatments (checked November 2026).
Written by the MadisonWI.com editors · November 9, 2026