Hows diatomaceous earth as a ipm against root aphids?

Super critical you wear a mask, use eye protection, and ideally gloves when handling and applying DE powder. It will wash off your hands...but you do not want to inhale any of it. It’s super light weight and disperses easily into the air. Serious lung damage can result even though it’s a non toxic substance. It’a akin to inhaling microscopic shards of glass. When you take the necessary safety precautions there is nothing to worry about.

I swear by it. It’s part of my organic IPM regiment. Thing is - it only works when dry. When I apply it as a top dress as described by others who’ve answered, it works. It’s value turns to silica when I then feed or apply any water to the medium. Helps strengthen cell walls and plant health. Look into beneficial nematodes. Those will penetrate your soil, are activated when wet since you apply with a watering, and will similarly destroy your root aphids but via different means then dehydration of exoskeleton. Good luck

This thing is abrasive, so most insects fatally damage their bodies when trying to move through it. To use diatomaceous earth, take a tea spoon and make a powder circle around the stem. You make can another bigger one as well. The lines don't have to be broader than 1/2 inch.

In the past it has worked great for me. I did an inner ring right around the stem and a ring around the edge of the pot. It compromises bugs waxy coatings so that their innards turn into teeny tiny bug jerky. Eventually it will work its way into the soil making it hard for bugs to move around and will end up buggering off.

I use diatomaceous earth on my top soil for bug prevention and any bugs trying to lay eggs in my soil ect. I have never mixed the dust with my soil to get to the roots so I'm not sure if it would reach the roots and kill your aphids, diatomaceous earth only works when dry, powdered form. Always follow the instructions on the label!