Green bamboo will bend to that diameter with a little heat no problem-
warm them over the grill.
Otherwise smack the nodes with a hammer and split the bamboo into
strips.
The next method would be small diameter rebar or even the reinforcement
panels bent into an arc and tied at the bottom and covered with
netting. After strawberry season you could use them to cage tomatos.

Metalworker, bamboo grower, mastergardener, strawberry and blueberry
grower, beekeeper, tinker of lamps and pots.