Another thing to keep in mind when grubbing out roots is the size of the roots themselves. Cutting roots larger than one inch in diameter can stress nearby trees and shrubs to the point of no return.Japanese grubber (Planter's Tool, #18.060.10) - Japan Woodworker
mattock (Garden Pick & Hoe, #18.061.60) - Japan Woodworker
long-handled grubber (Azada, grub hoe) - Easy Digging
long-handled straight-edge grubber - available at most large lawn & garden centers
serrated trowel (Gel-E Trowel) - Gardening With Ease
gardening knife, or hori-hori (Gardener's Friend) - Japan Woodworker