What Happens When a Tree Has Too Much Moisture?

Root Damage

• Exposure to saturated soil can cause severe damage to the root systems of many plants. According to North Carolina State University, soil with too much water can be just as dangerous for plants as soil with insufficient moisture. Saturated soil can drown plants by forcing oxygen from the soil and preventing their roots from absorbing nutrients. Symptoms of drowning include yellowing foliage, decreased growth and possibly death of the entire plant. The bark of drowning trees may fall away, exposing the plant's internal wood to infections of fungal and bacterial diseases.

Edema

• Edema is a condition that affects plants that absorb more water than they lose to evaporation. The moisture builds up in the tissues of the plant, causing bumps and swollen areas to emerge on leaves, stems and buds. According to the Clemson Cooperative Extension, insufficient light and cool temperatures also contribute to the onset of edema. Damaged leaves, which become discolored and eventually fall from the plant, cannot be saved once they start showing symptoms.

Fungal Root Rot

• Excessive moisture greatly increases the chances of fungi establishing themselves on the roots of a tree. A number of pathogenic fungi, including species from the Pythium, Botrytis and Rhizoctonia genera, thrive in saturated soil. These diseases infiltrate the roots of their host, causing severe symptoms that are often fatal to the tree. The foliage, stems and flowers of infected trees begin to wilt as the disease destroys their root system. Many of these fungi rely on water to propagate their spores through the soil. Trees infected with root rot are often destroyed and removed to prevent the disease from spreading.

Other Problems

• Several other problems can arise if the leaves and stems of a tree become too wet from long periods of rain or overhead irrigation. According to Clemson University, cold water can create pale blotches on leaves and may cause the tree's buds to fall prematurely. Leaf spot diseases, caused by various bacterial and fungal species, are also more likely to infect wet leaves. Applying room temperature water directly to the soil, rather than spraying the plant's leaves, helps prevent these issues.