- Maple trees are susceptible to the collar rot and the basal canker complex disorder, collectively referred to as maple decline. Collar rot is caused by Phytophthora citricola and basal canker is the result of the fusarium fungi, both soil-borne pathogens that enter healthy trees through the roots.
- An early sign of maple decline is rotting bark near the tree collar or the soil line. There are deep cracks in the bark with distinct water-soaked patches and spots. The rotting bark excretes water from the cracks. Bark pulls away easily to reveal discolored, rotting, brown to red cambium tissue beneath. Basal cankers range between 1 and several inches wide and appear near collar area. A severely infected tree contains up to 30 cankers at the soil line.
- The appearance of cankers and rot at the collar gradually stops nutrient and water conducting activities between the roots and the upper, healthy portions of the tree. Infected trees go into a slow decline as roots and trunk are girdled. The roots that are at a distance from the tree tend to remain unaffected. It is possible for trees to stay alive for up to several years after the appearance of initial symptoms. It is also possible for the tree to die completely within a year of infection.
- Since there are no chemical control options to cure the disease, the best management involves reducing conditions that promote fungi infection. Plant the tree in a well-drained soil as the growth of both fungi is encouraged by excessive soil moisture. Mulch trees adequately to reduce chances of mechanical injury to the root zone. Tree wounds frequently become entry sites for fungi. Protect trunks of newly planted trees from winter sun scald with the use of tree wraps.
Disease Identification
Symptoms
Damage
Management
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