There is a cutter designed for cutting black polyethylene tubing, up to 2"
in diameter. you can find it in the sprinkler irrigation repair section of
any store, like Fred Meyer or Home Depot. It looks like a pair of pliers,
one side of which is made of plastic and is concave to recieve the pipe. The
other side has a thin sharp blade. If you want to use the mature culms,
this device will cut them easily, if you rotate it around the culm, while
squeezing. It will not crush the culms, as pruners do.

I have used it to cut mature culms up to 1 1/2". Sorry, I dont know the
name of the device. It may be just called a tubing cutter.

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Robert L. Chehey

Boise, ID, USA, USDA Zones 6a, 6b. Heat zone 7
Cold, Mediterranean Shrub-steppe
and deciduous riparian forest
N43º38.67' W116º13.68' Altitude: 816M
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