Little known physics fact: all slopes become much steeper when it is YOUR butt in the seat.
Right now when your plants are still growing is an excellent time to hit them with herbicide. Have you identified the plant species in that area that are invasive/undesirable? If so, I would hit them now with the correct herbicide for those species. You can probably set them back another 6-10' with a good wand on a hand sprayer. I would pick a day with a gentle breeze that is blowing in the downslope direction - so you can spray deep into the area and YOU are not in drift mist.
