Citrus trees are flowering trees with dark green, fragrant leaves. Most citrus groves in the United States are found in Florida, Texas and California. Citrus trees are members of the plant family Rutaceae. Citrus trees produce citrus fruits such as oranges, grapefruits, lemons and limes. Although citrus trees are generally strong and hardy, all citrus trees are at risk of developing--and succumbing to--a root-attacking disease called root rot.
Root rot is a disease that causes a plant or tree's roots to become soft and mushy. When the fibrous fibers of the plant are destroyed by root rot, the root system is incapable of absorbing water and nutrients. Chronic root rot is treatable, but acute root rot usually leads to the eventual death of the plant.
According to the University of Pretoria, citrus root rot is usually caused by one of two pathogens: phytophthora nicotianae and fusarium solani. Both of these pathogens cause fungal infection in the roots or base of citrus trees.
Leaves changing from dark green to light green or yellow is an early indication of citrus root rot. Other indications of the disease are leaf drop and the death of branches. Mushrooms may be present at the base of the tree, atop the root system. Examination of the roots reveals epidermis (outer sheath) of the roots slips off of the roots with little or no pressure. Roots with citrus root rot are soft and doughy to the touch, rather than the woody texture of healthy roots.
Citrus root rot is treated with the use of fungicides. This is applied with sprayed liquids or the use of fumigation. If mulch is used, leave a maximum of 3 inches of mulch at the base of the tree. Too much mulch traps moisture; the fungal diseases that cause citrus root rot grow in the presence of excess moisture.
Citrus root rot is prevented by avoiding over-watering of the citrus plant. Clay-like and water-retaining soils retain too much water, which leads to disease of the plant. The addition of gardening sand, peat moss or organic mulch mixed in with the existing soil improves the drain rate of the soil. Water only when the top 2 inches of soil is dry to the touch.