Root rot is caused by overwatering, sometimes combined with temperatures that are too high or too low.
If a growing substrate is not allowed to dry out, it becomes depleted of oxygen, and the roots begin to rot.
Also called Pythium root rot, the most obvious symptom is brown roots. If gently pulled, the exterior casing of the root slides off.
Root rot can kill a crop, or at least cause it to stop growing.
But all hope is not lost! By drying out the substrate and paying close attention to subsequent irrigations, new roots will begin to emerge.
If temperatures are maintained within optimal ranges, you should be able to keep the disease at bay until the crop is harvested.