Symptoms
Hydroponics growers may well have at least one advantage over traditional growers as Root Rot infection tends to show up in the roots before it has much effect on the upper part of the plant. Roots that are subject to infection from Root Rot will begin to change from white to a light tan colour. The roots will tend to lose their glossy appearance and become dull brown in colour. Progressively the root turns browner and the roots will eventually soften and break up.
It should be a normal part of good management to check roots on a daily basis so this threat can be detected early. However, not every hydroponic system allows access to the roots and Root Rot may be harder to detect in Rock Wool systems or in Perlite.
Unfortunately, the aforementioned condition of the roots can be an indicator of other problems in the system as well as a warning of Root Rot problems.
Root Rot Infection Symptoms
Plants exhibit stunted growth. Leaves tend to curl downwards and become marked with necrotic spots (small black spots of decayed tissue).
Root tips are brown and dead. Further browning and softening of the roots will follow.
Plants wilt at mid-day and may recover at night. This is unfortunately a common symptom associated with many root problems in hydroponic systems, not only Root Rot.
Plants yellow and die. This is also a symptom of many other problems.