Today is June 30, and hurricane season has already begun. Summer rainfall and excess water will saturate the soil, harming the tree’s roots and, consequently, the entire tree. Citrus requires oxygen for respiration and growth, just like other trees. Florida’s soils contain between 20 and 21 percent oxygen. However, when flooding occurs, soil oxygen is replaced with water. Lack of oxygen will alter the organisms and the chemistry of the soil. If the flooding persists for more than three days in the summer at temperatures above 86 ℉, it can cause damage to citrus trees.
How do you know if the tree is damaged because of flooding?
Digging the soil and smelling the soil and roots is the most effective way to assess flood damage. Along with sloughing roots, sour odors, or hydrogen sulfide (rotten egg odor) are potential indicators of flood damage. In the absence of oxygen, anaerobic bacteria thrive and destroy citrus root systems.
When do signs of injury appear on citrus trees?
Symptoms of flooding damage may become apparent within a few days or weeks, but usually, appear after the water table has receded and the soil has dried. The major symptoms of flood damage are leaf wilting, leaf drop, and twig death, which occur because the damaged roots cannot absorb enough water. Other possible symptoms of flood damage include chlorosis, tree death, stunted trees, sparse canopy, small leaves, low yield, small fruit, small new flushes, and pale leaves. Excess moisture can cause foot or root rot. Root and foot rots are characterized by chlorosis of the leaves, lesions on the trunk near the soil surface, and root sloughing.
Flood management recommendations
- Develop a system of ditches, beds, and/or tiling when preparing land for planting citrus trees to eliminate drainage problems.
- Avoid disking a grove when trees are damaged by flooding.
- Reduce the amount of water but increase the frequencies.
- Collect a soil sample to check for fungal invasion. Apply an appropriate fungicide if phytophthora is detected.
- Make sure canals, retention/detention areas, open ditches, subsurface drains, beds, water furrows, and pumps are maintained well.
- Clean furrows and drainage ditches to keep them free of obstacles.
- Remove a portion of the tree canopy. This will reduce leaf transpiration.