It is a misunderstanding that soft-rot fungi are only found where there is wood.
From the newscientist.com
Sometimes, rhizomes injured by their feeding damage become infected with bacterial soft rot.
From the post-gazette.com
This will keep your irises free of borers and soft rot.
From the washingtonpost.com
Rhizomes infected with bacterial soft rot should be discarded, as there is no chemical control for this disease.
From the post-gazette.com
Also look for signs of soft rot in the rhizome.
From the charlotteobserver.com
Used by pathogens such as Erwinia to cause soft rot.
From the en.wikipedia.org
On tomato plants that already had fruits, damaged tomatoes probably have soft rot as well, and are not edible if that's the case.
From the kansas.com
They begin small and firm, then quickly enlarge, with white fungal growth developing under moist conditions that leads to a soft rot collapsing the stem.
From the sciencedaily.com
Affected tubers have a reddish-brown decay below the skin, firm at first but soon developing into a soft rot as the tissues are invaded by bacteria.