Forest Health > Insects and Diseases publication
Diseases of... Hardwood Root
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ROOT AND BUTT ROTS
Thinning foliage of a hardwood tree infected with a root rot fungus.
TABLE IX: Fungi Commonly Associated with Root Rots on Hardwood Trees in Florida |
| Pathogens: |
Various fungi |
| Common Host: |
Hardwoods |
Significance: |
Root rots are perhaps the most serious diseases affecting hardwoods in Florida. Many fungi are capable of causing root rots and some cause considerable decay of the butts of trees as well. Root rots are common on older trees, and trees which have sustained root or basal injury during construction or similar site disturbance. Most if not all root rots are aggravated by poor soil conditions (excessive moisture, poor aeration due to soil compaction, etc.). In addition, trees with extensive root rot are far less able to tolerate extreme weather conditions like extended droughts, long periods of heavy rain, or unusually high temperatures than are their disease-free counterparts. |
Recognition: |
Trees with root and butt rots characteristically exhibit varying degrees and combinations of crown dieback, loss and/or discoloration of foliage, and a generally unhealthy appearance. Internally, diseased roots exhibit varying degrees and patterns of discoloration and decay. It is not uncommon for diseased trees to live for years with little expression of symptoms by the crown. More commonly, however, trees with extensive root rot progressively decline and eventually die in a matter of several years. Stagheading, a dieback of crown branches resulting in a "deer antler" appearance, is sometimes common on trees with extensive root disease. In certain situations, where trees are exposed to severe weather conditions, for example, diseased trees may die in a matter of days or weeks. Conks or sporophores (fruiting bodies) at or near the base of declining trees are usually excellent indicators of root rot, but the identity of the fungus must be established to verify the diagnosis. |
Infection Biology: |
Most root and butt rot fungi affecting hardwoods are disseminated over long distances by means of airborne spores (basidiospores) produced by their respective sporophores. Sporophores are produced in many cases throughout the year in response to favorable conditions of temperature and moisture. Most root and butt rot fungi, however, tend to produce sporophores on a somewhat seasonal basis. Basidiospores preferentially infect injured tree bases and roots. As a result, basal scars and root damage stemming from construction or similar activities are often the sources of root disease. On a local scale, root disease fungi often spread from tree to tree by vegetative (hyphal or mycelial) growth from root-to-root via root contacts or grafts, or directly through the soil itself. |
Control: |
Control of root diseases in trees is a matter of PREVENTION. Effective treatments for curing established root diseases in trees are unknown. Sometimes careful crown reduction via pruning in conjunction with fertilization may prolong the life of diseased trees by reducing the transpirational demand on ailing root systems and promoting overall tree vigor. Prevent root diseases by avoiding root damage and wounds to the lower trunks of trees. When planting trees in areas where trees have previously succumbed to root disease, first remove old stumps and roots to reduce the local fungus inoculum potential. Consider soil sterilization with an appropriate pesticide such as methyl bromide or vapam, according to local demands and conditions, (ALWAYS following label recommendations). |
Bulletin No. 196-A | Printed October, 1983 | Contact the Forest Health Section |
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