Shirlee - you have concurred something that I am seeing as well. I use osmocote and added some to my seedling last year and saw impressive growth.
Hydrogen peroxide is used around my garden for so many things. I use it all the time when watering seedlings. Just a few squirts in the water. I've not lost any seedlings to damping off or root rot.
My seedlings have been outside for about a month now. I have to move older and bigger seedlings to another area so I have 2 raised beds to move the babies into. I just sowed more seeds. I must be crazy!! I need to do some serious culling. Or obtain more property ....