My best luck at treating bacterial soft rot, without digging the plant, has been to scrape, or cut, the "soft" parts out, pull back the soil, a bit, to exopse the "cut" area, and the top of the rhizome to the sun, and air, and sprinkle it with either Comet cleanser, drench it with a bleach water solution...or, if you can find it, a solution of a biocide (like Agrimyacin...that's spelled incorrectly
). Watering the plant , after the soil has dried out from the "drench", with "aspirin water" (4 aspirin tablets dissolved in one gallon of water), will help , a bit, also. Cut back the fans to about 6"-8" inches will also help to let in more "sun and wind". That said, I think it's better to DIG the plant, do all the surgery that's needed, give a good wash, and a short soak, in 10% bleach water (just the rhizome, NOT the leaves !!), dry well for a couple days, until the "wounds" crust over, cut back the fans, and then replant....drenching the soil, or replacing the soil, in the spot "might" be a good thing, as well (I have never really been able to see much difference, whether I did, or didn't
). Again, watering the plant with aspirin water seems to help (the acilacitic acid{again, NOT spelled correctly!
}helps kick start the plants immune system, to help fight the bacteria).
If there are a lot of plants....and a lot of rot.....you have a big job ahead of you, and , I wish you luck ! My "soft rot" issues are usually worse at bloom time.....wet weather, stalks in constant motion from the wind,(and the weight of buds / blooms", bending them over, and shading the plant bases, the extra stress of blooming, all contribute to promoting rot !