Wax Leaf Lingustrum – Roundup Causing Canker-Like Growths

Q: I have a wax leaf ligustrum that looks awful! It’s almost completely defoliated and is developing canker-like growths on every stem. Last summer I sprayed Roundup on the vines and weeds underneath. Could that cause my problem? 

A: The weed killer might well have caused the canker-like problem. On a hot summer day glyphosate, the active ingredient in Roundup, can volatilize and float upwards into the foliage of the shrub above, even though you didn’t spray it onto the leaves. At this point, all you can do is wait and see if the ligustrum survives.