Pandas - Python - How to change the contents of one column based on the content of two others?

I have two string columns and one datetime column:

I'm want to check if the first string column is a certain value then to check if the datetime column is before a certain date then to update the third string column to a new value.

I can create a variable to provide the date to match the datetime column against:

import time
june2014 = time.strptime('01-06-14','%d-%m-%y')

I'm looking for the syntax which can do this?