I had an interesting call last week. The caller had large roots growing in his irrigation valve box and wondered what he could do to get rid of them. We discussed products known to work against roots.His first problem was, why were the roots growing in the irrigation box? Roots grow where water is, which suggests that his valves or pipes were leaking and had been for some time because the roots were large. Secondly, there really aren't products that make roots magically disappear. The solution is to cut the roots, then put a root barrier around and under the …