Is spraying the leaves with Round-Up in Oct. adequate to kill bamboo or should all roots be dug up and their site sprayed as well? Does leaving a tarp over the site after digging up the roots prevent recurrence? If so, how long to leave it in place? Thank you.
The best way to control invasive bamboo is to cut the stalks down in the spring and allow new growth/leaves to develop over the summer.
Repeat the application in 14 days. (Be careful to protect non-target plants from any over spray.)
You should not need to dig up and treat roots as glyphosate is a systemic herbicide which is translocated to the entire plant for complete kill.