I use root riot cubes and get 100% success. But your problem is definitely to much water they are rotting. Try this first get a new bottle of gel or whatever and pour it into something clean when you dip them. Second is a sterile razor blade, your temp and humidity are right. So for the first 2...
I think the soil mix is wrong. Use 1 tablespoon of dolomite lime per gallon of dirt and still adjust ph in water. I fill a 3 gallon container with half fox farm dirt and half vermiculite and add 1 tablespoon lime for every gallon. I use bat guano high in nitrogen during vegetation, and switch to...
Thats what I was thinking looks like a nutrient lock problem. Adjust all watering to 7.0 in the jug. You want a high p ratio fertilizer and get plants on a schedule of 1 gallon of water every second day
I agree mighty wash will kill them. Do one treatment just before lights out so your plants do not get spots on them and them hit them again in 3 days and then rince the plants off the next day with just water.