Drought Stress or Too Much Water? They Look Similar

This is the most common misdiagnosis in landscape tree care, and the consequence is significant, because the response to one is the opposite of the response to the other.

Why they look alike

Both produce a tree that cannot move water to its leaves. In drought there is no water available. In saturated soil the roots suffocate, die back, and cannot take water up even though it is everywhere. The visible symptom — wilting and browning — is the same.

Telling them apart

Check the soil, not the tree. Dig down six to eight inches at the drip line. Dry and hard through means drought. Wet, heavy and possibly sour-smelling means the opposite. This single check answers the question most of the time.

Look at the pattern.

• Drought: browning starts at leaf margins and tips, and the whole tree responds fairly uniformly.
• Overwatering: yellowing rather than browning, leaf drop that starts with older interior leaves, and frequently a general dullness rather than crisp edges.

Look at the site. Low-lying ground, a downspout discharging nearby, irrigation running daily, or heavy clay under sand all point one way. Sandy high ground with no irrigation points the other.

Smell the soil. Saturated, anaerobic soil has a distinctly sour or sulphurous smell. That is a clear answer.

Overwatering is far more common here

In Central Florida, irrigation systems set to run daily on a landscape schedule are the leading cause of tree root problems we see. Trees do not want daily shallow water. They want infrequent deep water.

Established trees in this climate generally need no supplemental irrigation at all except during genuine drought.

Watering correctly

• Deep and infrequent. Water slowly, at the drip line, long enough to wet the top foot of soil, then leave it alone until it dries.
• Not against the trunk. Water at the drip line and beyond, where the absorbing roots are.
• Newly planted trees are the exception — they need regular water for the first year or two while they establish.
• Check before watering rather than watering on a schedule.

Root rot

Sustained saturation produces root rot, and by the time crown symptoms appear the root system may be substantially compromised. That is why drainage problems need addressing as drainage problems rather than as tree problems.