I am wondering if anyone had any experience in injuring roots and know of a good, quantifiable way to damage an already rooted plant without ruining the network too much. The goal of the injury is to try and mimic the damage that some insects consuming the roots would cause. I am using Alisa Craig tomato plants. 

I am thinking of getting a needle and just stabbing it in there multiple times to try. But if there is a better way of doing it I am all ears.