sub surface drip
Toro has a line and uses a herbicide in each emitter to help prevent root intrusion. I have a coil the rep left me, but have not used it.
Netafim has a nice tutorial online. They also sell a "filter" which secretes small quanities of the same herbicide (as Toro uses),with each watering.
Personally, I avoid herbicides in my equipement.
I have a netafim 0.9 gal/hr every 12 inches, 12 inches apart (staggarded) off headers on a small lawn area. We have Wester Red Cedars bordering it(notorius for root intrusion), and I am watching and waiting for root intrusion. Been in 1 & 1/2 years and still working. Have not dug up top check on roots, but will this fall. i did design it so the system drains completely after each cycle.
Augmented the native sandy soil with compost. 6 inches of mix on top of the netafim.
Have Fun, Jeff