|Is there a chemical preparation, preferably granular, that can be tilled into garden to eradicate horseradish---a noxious weed in my opinion.|
|Horseradish is tenacious, there's no doubt about it. Unfortunately, like dandelions, the roots grow very deep and are survivors. Repeated chopping or mowing in spring will eventually deplete the roots' reserves and kill the plant. You could try using a liquid herbicide and carefully "paint " it on the roots. Any other herbicide may cause damage to other plants in the area.
Another option is to give away the horseradish roots in a "dig your own" day. Invite neighbors and friends to take them away for the digging. Good luck!