newsticker-hide-old-items-in-newsticker-buffer

newsticker-hide-old-items-in-newsticker-buffer is a variable defined in `newst-plainview.el'.
Its value is

nil

Documentation:
Decides whether to automatically hide old items in the *newsticker* buffer.
If set to t old items will be completely folded and only new
items will show up in the *newsticker* buffer. Otherwise old as
well as new items will be visible.

You can customize this variable.