To tell someone to do (or not do)
This structure is used to convey instructions or requests to someone regarding what they should do or not do.
Examples
水をあげるように言います。
I tell (them) to give water.
雑草を取るように言います。
I tell (them) to remove the weeds.
肥料を使わないように言います。
I tell (them) not to use fertilizers.
Quick check
肥料を使わない___。