One of my avocado plants got rot rotten two months ago and since then it has spread to all my other avocado plants. I have tried everything I can find online to cure the root rot including adding Perlite to the potting soil; repotting the plants in new soil after cleaning much of the rotted roots; using clay pots for better oxygen penetration; reducing the frequency and the amount of water added every week and adding a 3% hydrogen peroxide solution every time I water the plants. Unfortunately, everything I have done seems to have not helped the plants and I'm out of ideas. I have been growing these avocado plants from seeds for almost a year and it pains me to see them slowly getting devoured by this virulent root rot disease. Any advice on how to deal with this would be much appreciated.