Killing off sycamore roots

Hi

Last year we had some sycamore trees cut down. I had applied glyphosate to the stumps within a day or two, and about a month later the stumps were ground out.

Now, some of the roots which were left in the ground have started suckering. Very soon I'm gonna have another sycamore tree.

What's the best way to kill off the roots? Chop into an exposed root and put more glyphosate in there?

Ta

Glyphosate is ineffective against woody growth. It should only be applied to foliage. You need to use a woody weedkiller like SBK or roundup do a stump and woody weed killer product. It will have a different active ingredient like triclopyr

Thanks.

Regardless of the weedkiller type, what's the best way to get it to kill off the remaining roots (which are too large to dig out). I was thinking to cut them at a few places and apply killer.

Much as I hate to contradict @r896neo, who I believe do this sort of thing for a living, I think he has made a mistake in just advising against glyphosate and then suggesting Roundup.

Glyphosate weedkiller was developed by Monsanto and marketed by them under the name of Roundup. Most, if not all things, sold under the Roundup name only contain glyphosate as an active ingredient. E.g. Roundup Tree Stump Super Concentrate
https://www.roundup-garden.com/weedkilling-products/tree-stump-root-killer
and the View Label button downloads a PDF that says
"ROUNDUP® STUMP KILLER is a soluble concentrate containing 360 g/l (28.47 %w/w) glyphosate acid (present as 441 g/l (34.86 %w/w) potassium salt of glyphosate)".

AFAIUI, glyphosate is an effective weedkiller because it is absorbed by the foliage and then translocated through the whole plant, including the roots, and so kills off everything.

However the PDF I referred to earlier does have instructions on how to use the Tree Stump Super Concentrate on freshly cut or standing trees. So maybe this is applied differently (higher concentration? more thickly?) than a spray and it does get absorbed by the woody parts.

So if you use a Roundup product you may well want to make sure it is an appropriate one.

Your quite right Steven, I had just assumed round up stump killer was not glyphosate its only something I gave seen on shelves at diy stores and have never looked at it closely.

Apologies for any confusion, I'm not totally up to speed with diy weedkillers. I use different professional use only products products as I have a license.

Application to stumps or roots is simple. Just make a fresh cut and then dab a bit of weedkiller on with a sponge.