changing background colour when stringvariable is higher than 5 (tkinter/python) : my problem is that iam trying to change a background colour to change when the(string)variable is higher than 5. 
this is the code:

    colour_p1="White"
    kills_p1 = IntVar()
    kills_p1.set(0)
    def kill_count_p1():
    kills_p1.set(kills_p1.get()+1)
    Label(master, textvariable=kills_p1, bg=colour_p1, font=("Courier", 20)).grid(column = 4, row=2)

I have tried a few different ways like "if", but it keeps it on the same colour all the time. I want the background to be yellow when the variable "kills_p1" is higher than 5. 
ps. this is only a part of the project and not the whole