Bamboo spreads by underground stems called rhizomes. Clumping bamboos have short rhizomes and spread slowly, but running bamboos produce very long rhizomes which give rise to leaf stalks called culms far from the main clump. To prevent a running bamboo from spreading, a "rhizome barrier" is essential. A barrier two or three feet deep is effective. It should be slanted at a 45 degree angle outward at the top so that when the rhizomes hit the barrier they will bend upwards. A barrier does not stop a running rhizome, it only deflects it. The barrier should project an inch or two above ground level. Check the barrier once a year, and cut off rhizomes that arch over the top.
Barriers can be concrete, metal, or plastic. An effective and often-used material is high-density polypropylene, 40 mil or heavier. Where 2 pieces meet, they should overlap and be glued, taped, or held together with stainless-steel clamps. This material, commonly called a “root barrier”, comes in rolls, or as hinged sections and is available from some landscape suppliers and bamboo nurseries. More elaborate barriers with corner posts that hold the material at the proper angle are also available.
To remove the bamboo that has grown into your yard, first cut the underground rhizomes where they enter from an adjacent property. They usually grow in the top foot of soil and can be cut with a spade, mattock or saw. If only a few rhizomes and culms are present they can be dug up and removed. A large mass of bamboo can be killed without herbicide treatment by cutting off all of the culms at ground level and continually removing new culms as they appear. Continually removing culms to preventing any foliage growth will deplete the plant's stored food and eventually kill the clump. With this process it may take a year or more for a clump to die.
The non-selective systemic herbicide glyphosate (Round-Up) can be painted on the end of culms immediately after they are cut, or foliage can be sprayed with a dilute solution if nearby plants will not be damaged by spray drift. Glyphosate is absorbed by plant tissue and transported within the plant. The herbicide inhibits new growth, but more than one treatment may be required to kill well established clumps of bamboo.
By V. Lazaneo, Urban Horticulture Advisor, Emeritus, UC Cooperative Extension, September 2012