If it's a "smelly" rot...it's bacterial, and bleach...or *Comet cleanser with bleach, will help heal the "wounds"....scrape out as much of the "mush" as possible, then sprinkle the Comet on the wound (or, drench with a 10% bleach water mix). If they are really affected, digging...then cleaning and dipping in the "10%" might be the best option. Make sure the "wounded area" is left exposed to the air / sun, so it can "scab over". Without knowing your soil composition...or it's ph....it's hard to give ant recommendations on "soil improvement", but . "DRAINAGE & AIRFLOW" are VERY important for keeping bacterial soft rot away...and for curing it, when it pops up !!