I believe that evil is a curse.
I do not believe you can put a curse on anyone as it will come right back to you.
This is called Karma of course.
I believe through the Holy Spirit we are all given certain gifts to serve the world with. However if these gifts become misused than they are recognized as a curse but to only them as they dig their own graves.
Negative thoughts will bring negative actions but in your own life.
A good movie/documentary to watch on this is "secrets"
The quote on the tongue is a good one, yes our tongues can become deadly poison, once we put something out there it can never be returned.
The only curses we have our the ones we feed ourselves.
If you hurt someone, it comes back ten fold or more and this is your curse.
If you say to someone you have cursed them, they may fear and the curse lies in their minds only.
Only satan can curse, however he cannot go further than God will allow. So if you follow God's word, you will never be cursed.