I dug up half the tuber and disposed it because it was rotted but the other half of the clump seemed firm. Ergo, I am in a quandry.

I am looking for someone to tell me if this is a virus or rather leafhopper(s) (which I am fairly confident I have at this point)damage and what actions I should take at this point.

And if I dispose of the plant, is there someway I can sanitize the ground and transplant another dahlia in that spot?

Further, the dahlias on either side of the affected one appear quite healthy. Should I now spray them with Pyrethrin as a preventative? I have bumblees and would really prefer not to do this.

Bugging out, so thanks for any feedback!

Cheers,
Russ

I agree with you Russ. If you've ever read the Pyrethrin instructions, you can be assured it's just as toxic to humans and beneficials as the "non-organics". But I've been shooting the dahlias with soapy water and it doesn't seem to be working.

And thank you. Based upon your observation I went back to the WSU website and admit their mottling doesn't appear to have the amount of dieback I am getting around the edges nor can I find the same patterns of mottling they mention. But it may be a mute point because the virus's are generally spread through aphids and leafhoppers.

I have found a few leafhoppers and a few aphids but not enough to explain the pathetic condition of this plant so I am still wondering...