Root Rot is essentially a sign that your cannabis plant is suffocating and not receiving any oxygen from the roots. This happens when certain fungi, algae and bacteria grow on the roots preventing any oxygen from passing through. The cause for their growth is usually due to overwatering your cannabis plants and from a lack of drainage. When a plant has Root Rot it will grow very slowly, and its leaves will begin to twist and curl up. In the beginning the leaves will only change slightly in color which is a distinguishing detail to Root Rot, as in other cases the leaves will change color right as they start to curl up. If the problem is not cured, the leaves will eventually bleach and turn crispy. The plant will stop growing and completely die in a matter of weeks. If you are growing in a Hydro set up, you will notice the roots will turn brown and become very slimy with a lot of growth all around them. That is what suffocates the plants.
How to Cure:
The easiest and most affective way to cure Root Rot, is to water your affected plants with a hydrogen peroxide mixture. All you need to do is mix 4 parts water with 1 part 3% Hydrogen Peroxide, and then water your plants with that until you no longer see signs of Root Rot on new growth. This could take a couple of weeks to complete before being completely cured.
3% Hydrogen Peroxide