Not necessarily for the dust bin.
You would be surprised with how easily SOME fungus rubs off with a bit of household ammonia. Of course, you have to get INSIDE the lens if the fungus is on the inside. But some lenses are rather easy to dismantle, usually just unscrewing the front ring and then removing the screws. On some lenses, the rear element set's removal is even easier: simply unscrew the rear element ring with a pair of pliers. Do not force anything and, as I inferred, this method cannot be applied to all lenses. - David Lyga