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Diseases of... Hardwood Root/
ROOT AND BUTT ROTS
TABLE VII: Fungi Commonly Associated with Root Rots on Hardwood Trees in Florida
Armillariella tabescens (formerly, Clitocybe tabescens):
The cause of Mushroom Root Rot. Common on sand pine of all ages under a variety of field conditions in both planted and natural stands. Appears to act an an opportunist, primarily attacking trees infected with one or more other fungi or trees suffering from other stresses or injuries. Produces clusters of fleshy, tan to brown toadstool-like mushrooms, most often in the fall, which are gilled on the undersurface of the caps. Also frequently produces characteristic sheets or mats of fungus tissue beneath the bark of infected roots and tree bases. Mats are often perforated with small holes throughout. Often found on water-soaked roots some distance from the base of infected trees. Laboratory analysis recommended for positive identification in the absence of sporophores or the characteristic fungus m ats.
Fungal mat (mycelial felt) of Armillariella tabescens beneath the bark of an infected sand pine root. Note minute perforations in fungus tissue.
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Inonotus circinatus (formerly, Polyporus tomentosus var. circinatus):
The cause of Red Root and Butt Rot. A major pathogen, especially on older (more than 20 years of age) sand pines in both planted and natural stands, including commercial seed orchards. Produces stalked (on the ground above decayed roots) or bracket-like (on the tree) sporophores with porous undersurface at or near the base of infected trees. Sporophores produced at various times, but most commonly during late fall or winter. Sporophores light yellow-brown to brown, spongy or slightly leathery. Decayed wood and roots exhibit reddish to red-brown discoloration and eventually a rot flecked with small elliptical white pockets. Laboratory confirmation suggested when sporophores are missing.
Typical conks (sporophores) of Inonotus circinatus at the base of an infected, old-growth sand pine. |
Heterobasidion annosum (formerly, Fomes annosus, Ref. Annosum Root Rot):
Not common on sand pine, but does occur, especially in thinned plantations due primarily to the stump colonization habit of the fungus. Tough, leathery sporophores produced on infected roots or in the duff or litter layers at bases of infected trees. Mature sporophores grayish to brown on top and white to cream-colored on the porous under- surface. Internal root decay typically yellowish and stringy in advanced stages. Laboratory confirmation recommended when sporophores are absent. |
Macrophomina phaseolina:
The cause of Charcoal Root Rot. Occurs in forest tree nurseries where it can be a destructive pathogen on seedling sand pine. Occasionally detected on roots of young, dying trees in commercial forest plantations. Apparently not a major factor in the overall sand pine root disease syndrome. Often produces hard, minute (less than ½ mm), black granules called microsclerotia beneath the bark and cortex of infected seedling root collars and roots. Microsclerotia may be seen with the naked eye and are readily visible with a hand lens. Laboratory confirmation suggested to confirm diagnoses.
Small black microsclerotia of Macrophomina phaseolina as seen with a hand lens beneath the bark of infected sand pine roots (diagnostic for charcoal root rot).
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Phaeolus schweinitzii (formerly, Polyporus schweinitzii):
The cause of Brown Cubicle Root and Butt Rot. Typically occurs on old to overmature trees, but not limited to trees of older ages. A significant, but not major component in the sand pine root disease complex. Produces bracket-like (at tree bases) or stalked (on the soil above decayed roots) fruiting bodies (sporophores). Upper surface of fresh sporophores velvety, concentrically zoned, reddish-brown with a yellow margin (when fresh). Under surface dark colored (olive) with large irregularly shaped pores. Decayed wood and roots eventually become brittle and break into large yellow-brown to reddish-brown cubes. Laboratory confirmation advised in the absence of sporophores or typical decay.
Sporophore of Phaeolus schweinitzii near the base of an infected old-growth sand pine.
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Phytophthora cinnamomi:
A water mold fungus. One cause of Phytophthora Root Rot. Well known to foresters as the cause of littleleaf disease of shortleaf pine in other parts of the Southern U.S. Especially damaging in shallow or poorly drained soils. Occurs in forest and ornamental nurseries and in commercial forest seed orchards. Predominant pathogen in young sand pine plantations. To date, unknown in natural stands of sand pine. Likely moved into field plantings via infected nursery stock, contaminated equipment, or infested soil. Infects primarily smaller, feeder roots. Cortex of feeder roots apt to slough when pulled between fingers. No visible signs (sporophores or other structures) produced in the field. Diagnosed only by laboratory analysis. |
Phytophthora parasitica:
A water mold fungus. One cause of Phytophthora Root Rot. On sand pine to date, known only in forest and ornamental nurseries. A problem under poorly drained soil conditions. Apparently a minor component of the sand pine root disease complex. No visible signs produced. Diagnosed only by laboratory analysis. |
Verticicladiella procera:
Role of this potential sand pine root pathogen not well understood. A known pathogen on other pines in other parts of the United States and is frequently recovered from diseased sand pine roots. Sometimes associated with mechanical and/or apparent insect damage on roots. No visible fungus structures produced in the field, nor are symptoms definitive. Laboratory analysis required for positive identification. |
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Bulletin No. 196-A | Printed October, 1983 | Contact the Forest Health Section |
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