Root Pests? Root Pesticides?

How often do you guys deal with severe root problems like pests? Everyone's heard of root fungus in a hydroponics system, but are roots a high-maintenance factor outdoors? Are harmful bacteria, insect larvae, or fungi a major concern? If so, is there some sort of pesticide I could invest in? Thanks

just put a plastic bag around the roots
and poke a few holes in itt!