It's only a desiccant so doesn't exactly kill but dries to the point where the plants are unable to photosynthesize. You need to apply to actively growing plant tissue (not dormant or hibernating bulbs) and it needs sun to trigger the phytotoxic reaction. Doubt you will have great success using it at this time of year.

btw, it is nonspecific in its effect so if you get it on the azalea or any other leafy plant, it can damage it - but not kill it - as well.