In Pikmin 2, Ravenous Whiskerpillars can appear in their vicinity, as well as some type of mold that shows up and keeps the plants from growing. This can be destroyed sufficiently quickly with a medium-large group of Pikmin.
Each plant can have up to five berries at once. Some only contain red berries, some only purple berries, and some contain a mix of the two. In Pikmin 3, since the ultra-bitter spray does not return, only the red-berry Burgeoning Spiderworts exist.