And the answer is...It depends. If you cut rhizomes that recently went over the barrier and didn't establish themselves, then you will have stopped them. If you let them get established and then got around to cutting them, they may be independent plants that you will have to dig up. However, you don't need to worry about any small pieces of roots: the only thing you will get a new plant out of is the rhizome section itself. Bamboo is not like horsetail or Japanese Knotweed where the plant regenerates from a small piece or fragment.

Yank up anything that has escaped, period. If it has roots down and is difficult to get out, then it has likely established itself outside the barrier. Dig it up... don't just sit there, go do it right now!

Been digging it all up like crazy.. just worried small sections I couldnt get to will get established and keep going.. been a nightmare as it got into both neighbors yards and my HOA area.. I heard if small sections start growing and you break off any new culms it will eventually die off and exhaust itself.. hopefully this is correct or I am in for another nightmare next year.. worried it might get to my koi pond and start popping through the liner.. if that happens I am done for but so far none has I think... all boo jumped over my barrier none went through it or under it so that was good.. Also this years culms.. year 4 are really not bigger than last years.. getting frustrated as I really want the 2-3 inch culms but I am still getting 1/2 inch and 1 inch ones.. dulcis and p. aureocalis F is what I have..

As long as you found ALL of the escaped rhizomes, and cut them off, then yes, killing any new growth will eventually kill it. Just be diligent about it. Depending on how long they have established themselves, rhizomes will store energy to develop new shoots for some time, but they need photosynthesis to continue to live and grow, and all it takes is one culm to feed it, so look around carefully. Here's a good link to information on this http://www.americanbamboo.org/GeneralInfoPages/ControllingBamboo.html
I think the part about heavy watering and fertilizing may be a bit extreme in your case, but you'll get the idea.
Since rhizomes tend to grow only a few inches below the soils surface, you can use a spade to follow the ones that escaped, and to detect new ones that you have not found yet. Do a search on rhizome pruning. Rhizome pruning seems to be an excellent form of containment if done twice a year, and may be a way to help protect your pond liner. Kudzu9 is an expert on this subject.
Lastly, check your barrier twice a year for now on for any escapes and cut them off so they can't get established. Also double check the seems, as that is an area where one of my barriers failed.

kevip-
I don't want to minimize your situation, but you sound like you're letting yourself get a little too hyper about this. I have no barriers for about 70 bamboo in my yard, and every year I have a few rhizomes that get away and have to be corralled, I chop the rhizome and pull up the main part; lots of pieces get left in the ground, I've yet to see one grow back from a small chunk. In fact, each year I take the choicest parts of my rhizomes and use them to try to propagate new plants. My success rate is about 0-40% when I try really hard.

If you've gotten the main rhizomes, you've got most of the problem licked already. You may have a few weak, small strays left somewhere, but they shouldn't be tough to spot and remove if they come up. It should only be an issue if you let them escape several years ago and did nothing until now.

Kudzu I should post pics... it came about a foot or so from breaking into my pond.. it is now in my others neighbors yard for sure now as its coming up now.. its a complete mess partly my fault for not checking my barrier as all boo jumped over.. I am now digging up about three to four feet of my yard from where its planted.. its popping up everywhere and some roots have grown 8 ft from where its planted.. luckily it is only about 6 inches or less down.. if it went under my barrier I would be screwed.. currently I am taking even the dirt with spare small roots out and trashing them all and will resod my yard as I cant take any chances as I have over 15 thousand worth of koi in my pond not to mention the pond itself.. I am still wondering though where I cut the rhizomes if that root will still redevelop and keep spreading or will it stop there..

as another fact I took a small section that escaped last year and put it in a pot.. it put up new shoots this year so even small sections will keep growing.. anyway with all said and done will check a bit more carefully for now... I thought I was ok with my barrier as nothing really broke it for three years.. this year though it exploded with growth even though the culms arent any larger..

Kudzu I just want to be reasured on what I know already about boo.. another note.. those infected sagos I got from houston about a year or so ago are weird.. they never put out any new growth despite fertilization and prunning.. weird as my others have.. they did have some pups attached that put out growth but what really good is that as it looks odd as a one or two growths pop out at the bottom of the plant.. I gave one to a friend and it is now a complete sago..

kevip-
Which species of bamboo is doing this or is it more than one? I'm glad you didn't take offense at my last post; I wasn't doubting you, but I have a fair amount of experience with bamboo and have just never seen it go quite as nuts as you're describing. How long ago do you think it jumped the barrier?

I also totally empathize about the koi pond. I went on a dig a couple of years ago to remove Black bamboo which had been planted too near a koi pond and it went under and pierced the 60 mil EPDM liner.

Hopefully, you've got it under control now. I looked at your web site and you do have a lovely set of plantings, so I hope this experience hasn't soured you on growing bamboo. I would think that in the future, if you whack the rhizomes as soon as they make a run for it, you'll not have to worry. Good luck and please post again on this as I'm very interested in whether all your effort gets it finally resolved.

Not sure when it popped over as the culms only came out this year outside the barrier, my guess instead of putting out new bigger culms it was just spreading underground each year. The two I have, well actually I have three but one is a clumper.. P. Dulcis and P. aureocaulis F. I already pulled a muscle in my chest which has slowed my efforts but I am getting it all out and will lay down new dirt and probably resod rather than seed.. your welcome to come over and help me dig it out.. free boo roots and some culms for anyone that wants them.. you wont have to wait long for 1 inch culms.. I figure it will take me at least another week to get out all the escaping boo.. I have to stop on my yard and clear my neighbors yard this weekend.. thank goodness both my neighbors dont mind me digging up their yards.. all the boo in the barrier will stay..

Kevin-
I'm in the Pacific NW and have the same USDA Zone as you. I actually considered dropping by to help out...until I realized that you're in Texas! From your descriptions, it sounds like it's been at work underground for 1-2 years, so that's why they are so well established.

I thought you were local unless I am confusing you from someone else with the sago freebees from Houston.. anyway it popped up again now under my crimson maple.. great.. probably will have to dig up the maple to get it out and may lose the maple which I have had for years.. can I say life sucks.. I cant even breathe without my ribs hurting so imagine me digging and pulling this crap up.. I need help so any locals to Dallas area please pipe in.. I will pay a bit for any help..

I would hire day laborers but as you know it takes some skill getting this out.. if they dont know what they are doing it will only cause more problems next year.. and I agree it was probably growing and not coming up for more than a year.. this led me to a false sense of security that it was contained..

Haven't touched a sago in my life, and last time I was in Texas was passing through on business 15 years ago. But I accept that my screen name does have a certain resonance in the Southern U.S....

I thought it was you but was over a year ago and my memory is not that great.. I have almost all the errant dulcis out of my yard 4 more roots to go then its over to my neighbors yard to finish up.. After that will start on the aureocaulis.. man I am tired.. I hope I dont have to do this again as I am tearing up my yard big time.. at least my pond is finally clearing up.. got a new Becko last week will post some pics of my koi after all this work is done.. all my babies are getting pretty large, I still have a Ochiba to pick up but as you might know my city got hit with strong storms and tornadoes this past week so my local koi place is still cleaning up so will have to wait a bit longer to bring her home..

If I plant bamboo will it escape cultivation and spread into tnhe neighboring farm fields (wheat corn soybeans) and pastures? If the farmers routinely plow, disk and herbicide the fields will this kill any of my renegade escapees? I don't want the agricultural community comming after me.
zone 6 So West Ind near the Ohio river. soil is clay gumbo

drtluvr-
I think you've been watching too many episodes of Night of the Living Dead! Seriously, bamboo does spread, but it's not difficult to keep under control. Any stray runners are going to send up culms and advertise their location. And you can prevent 99% of even that by root pruning around the plant with a sharp spade once a year. I have bamboo that spread all of 10 feet in 30 years and I have bamboo that has sent out 10 foot runners in one year. But it's not going to go great distances without you knowing about it. And it's not invasive in the sense that pieces of root left underground will reproduce. Chopping off a runner will typically kill anything past that point unless you've let it get established as seems to have happened above. Lastly, in your Zone, the cold winters will limit growth and travel.

My brother had a bamboo problem and stopped it cold. His neighbor had the extra fast growing variety that that sent shooters out along the ground or just under the surface. My brother found himself trimming new bamboo plants that were running under his fence almost daily.

He rented a trencher and dug a 4ft deep, 4 inch wide trench along his side of the fence, about 12 inches from the fence. He inserted in the trench several heavy galvanized "wavy" metal sheets (The type you'd use for shed roofing). Buried them right so they were flush with the surface. Covered them up and has been bamboo free for almost 10 years now.

Man can you come do my yard?? I got several ten foot runners already that I have dug up.. hope your right kudzu and if I chop it will stop.. as it went under a crimson maple and I dont want to kill the maple to get it out.. I can chop where its at so hopefully it doesnt put out any more runners where I chopped... my other side of the yard all the runners stopped at the low point in my yard as water gathers there after every rain.. this rotted off all the boo so it contained it there as boo wont grow in saturated soil, it got about 6 ft from the orignial planting.. my dulcis though there is no low point.. the culms grew 6 feet tall in one week in my neighbors yard.. and he cut them all off.. which made it even harder to find it to dig it out.. urg.. I hated to delay digging it out but my body had to rest.... spent all the weekend getting it out of my neighbors yard.. so glad I have understanding good neighbors.. heard so many horror stories on these forums of bad or mean neighbors..