Hello Kevin,

This is a really unusual question - thanks for sharing it! I have been growing dahlias for many years in the Willamette Valley, but I have never seen damage quite like your second picture. The first picture appears to me to be rodent damage - mice or voles will sometimes burrow underground and munch on tubers. Once a bite happens, that tuber is more susceptible to rot. In this case, the damage looks minimal, and the bulb may survive.

But that second image, with the perfectly round hole, has me stumped. It looks more like insect than rodent damage. I am not aware of common insects that would bore a hole that large into dahlia bulbs, and none of the resources I consulted mentioned this kind of pest damage. You might consider sharing this picture with a regional commercial dahlia grower, such as Swan Island. They might have thoughts as to what would cause this.

Wishing you a fabulous dahlia season!

-Sarah Bronstein, MG 2022