Wands cannot accept swords as a tool, and will not "Use" shears or "Destroy" with them if used on kelp. This means one cannot "trim" kelp as added in a vanilla feature to keep vines and other plants from growing too long, and also that one cannot use a wand to destroy / harvest kelp in a large area.

I was trying to control for a spawn from a mod pack, and the spawn becomes invalid with kelp at the surface of the water, so I tried to evenly trim down the entire kelp field and... Nothing seems to work!