Forest Health > Insects and Diseases publication
Diseases of... Conifer Stem
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RED HEART OF PINE
Sporophore of Phellinus pini on the stem of an old-growth sand pine. Cut-away portion shows typical "red heart" decay.
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| Pathogens: |
Fungus Phellinus pini (formerly, Fomes pini) |
| Common Hosts: |
Pines Pinus spp. |
Significance: |
Although red heart affects all of Florida's pine species, it is a disease of serious magnitude only in mature or over-mature trees. In such trees it can result in significant timber losses due to wood decay (heart rot) resulting from infection by the pathogen. Red heart can be found in pines in both landscape and forest environments. This disease does not kill trees, since the pathogen only attacks the internal, physiologically inactive (non?living) heartwood. Trees with advanced infections, however, are subject to wind breakage due to the structurally debilitating effects of the associated wood decay. Rarely, if ever, is red heart a problem on younger trees. |
Recognition: |
Red heart is most readily detected on standing trees by the appearance of fungal conks (sporophores) of the pathogen on the stems of the infected trees. Conks are bracket-shaped or hoof-shaped, usually several centimeters across, brown or brownish black on upper surfaces, and often have concentric grooves paralleling their typically lighter, golden-brown margins. The undersurface of conks is grayish-brown to brown and minutely porous. Conks are usually woody, and located predominately at knots or branch stubs. They are also perennial, remaining attached and active (i.e., producing spores) for years. Internally, old conks often exhibit annual layers of spore-producing tubes (pores), which are similar to the annual rings produced by most tree species. Hence, it is sometimes possible to determine the approximate age of certain sporophores. Old conks are sometimes covered with moss on their upper surface. Internally, heartwood in the beginning stages of decay is typically stained reddish or reddish-brown. Advanced decay is characterized by elongated white pockets or flecks separated by apparently sound, sometimes resin-soaked wood. |
Infection Biology: |
Red heart infections occur primarily through dead branch stubs and presumably, in certain cases, through deep stem wounds. Airborne spores of the pathogen are deposited on or close to these points of entry and germinate when conditions (moisture, temperature, etc.) are suitable, allowing the fungus to penetrate into the susceptible wood tissues. Following sufficient development and decay by the fungus in the heartwood tissues (many years in most cases), the pathogen produces its typical conks or sporophores at branch stubs on the surface of infected stems. New infections can then be initiated via spores produced in the porous undersurface of these new sporophores. Additional new infections can at the same time arise from spores produced by older, perennially active conks on the same or other trees. |
Control: |
Once established, red heart infections cannot be effectively or practically treated. Prevention of infections by avoiding unnecessary damage or injuries and properly pruning pines is recommended. Proper pruning involves the removal of dead branches and branch stubs with clean cuts, just outside their somewhat swollen or callused branch collars at the trunk of the tree. Timber losses due to decay-induced lumber or product degrade can be minimized by harvesting pine stands before they sustain significant losses. The harvest of mature or overmature timber thus should not be delayed. |
Bulletin No. 196-A | Printed October, 1983 | Contact the Forest Health Section |
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