Root rot can be caused by several different organisms including types of bacteria, fungi and parasitic oomycotes. Although the symptoms are similar between different types, they don't always look exactly the same. However, growers generally refer to all types of unhealthy root browning as just "root rot."
But because plant root rot can be caused by different pathogens, a solution that solves the symptoms for one grower may not necessarily work for another grower. That being said, there are ways to fight against root rot no matter what kind you have!
Some types of root rot affect the roots below the surface of the water
Cannabis roots just got root rot - brown roots and leaves are wilting - often triggered by heat
And sometimes it's only the roots above the surface of the water that turn brown, while the roots in the water stay white
Sometimes it's only the roots above the water that are being affected, and the roots in the water itself are still relatively healthy
The first sign of root rot is usually wilting, and root rot often strikes immediately after a reservoir change, especially for young plants. If this happens to you it's recommended to only top off your reservoir for the first several weeks, and wait to do the first full reservoir change until after the roots are well established. This allows young roots time to build up a biofilm that protects them against root rot during reservoir changes.
The first sign of root rot in hydro cannabis plants (besides brown roots) is usually wilting
Cannabis root rot can cause leaf symptoms that can look like almost anything: cannabis leaves get burnt edges or tips; yellow / bronze / brown spots or stripes; nutrient deficiencies; clawing and curled edges; and other unusual leaf symptoms.