U.S. Department of Agriculture • Forest Service

Forest Insect

& Disease

Leaflet 76

Revised March 2018

Heterobasidion Root Disease in

Eastern Conifers

Glen Stanosz1, Michelle Cram2, David Coyle3, and Linda Haugen4

1

Professor of Tree and Forest Health, Department of Forest and Wildlife Ecology, University of WisconsinMadison, Madison, WI

2

Plant Pathologist, USDA Forest Service, Forest Health Protection, Southern Region, Athens, GA

3

Forest Health Extension Associate, Southern Regional Extension Forestry & University of Georgia, D.B. 

Warnell School of Forestry and Natural Resources, Athens, GA

4

Plant Pathologist, USDA Forest Service, Forest Health Protection, Northeastern Area State and Private 

Forestry, St. Paul, MN

Introduction

Heterobasidion root disease (HRD) is 

caused by distinct but closely related 

fungi in the Heterobasidion annosum 

species complex. Older common names 

for HRD include annosum, annosus, 

or Fomes root disease or root rot. This 

disease causes growth loss, root and 

butt rot, and mortality of conifers. 

Damage by HRD in thinned conifer 

plantations can be especially severe, 

and it is one of the most economically 

destructive of all forest tree diseases.

Hosts and Distribution 

Heterobasidion irregulare was formerly 

referred to as the “pine-type” (or 

p-type) of H. annosum due to its 

frequent association with pines (Pinus

spp.) in both Eastern and Western 

North America. Because H. irregulare

is the only Heterobasidion species 

known in Eastern North America, 

historical references to H. annosum in 

Figure 1. Crowns of dead eastern white pine 

(center) and dying red pine (right) affected by 

Heterobasidion root disease.

the East are now presumed to refer to 

H. irregulare. A second Heterobasidion 

species, H. occidentale, was formerly 

known as the H. annosum “s-type.” It is 

known only in Western North America 
2

and is most common on spruces 

(Picea spp.), true firs (Abies spp.), and 

Douglas-fir (Pseudotsuga menziesii).

In the Eastern U.S., HRD is usually 

found within the historical range of 

pines and eastern red cedar (Juniperus 

virginiana). Although the known 

geographic distribution of H. irregulare

has recently increased, there are still 

large portions of the Central U.S. 

and Great Lakes Region occupied by 

conifer forests where HRD has not been 

reported. In contrast, the pathogen is 

widely distributed in the Southeast, 

where its abundance and the resulting 

severity of HRD damage vary with site 

conditions and tree species. 

All native pine species occurring in 

the Eastern U.S. are susceptible to 

HRD, along with eastern red cedar. 

In the Southeast, longleaf pine (Pinus 

palustris) is the least susceptible host 

of H. irregulare, while loblolly pine 

(Pinus taeda) is the most susceptible. 

Eastern white pine (Pinus strobus) in 

the Appalachian Mountains has also 

experienced severe damage by HRD. In 

more northern areas, red pine (Pinus 

resinosa) is the most common host, 

but H. irregulare also frequently kills 

eastern white pine, jack pine (Pinus 

banksiana), and less commonly fir and 

spruce. Many other native conifers 

and those introduced to the Eastern 

U.S. also are likely hosts. Although 

H. irregulare occasionally has been 

reported in hardwoods, the role of 

these species in the epidemiology of 

HRD is not clear. 

Symptoms and Signs

Site-level symptoms. Mortality caused 

by HRD in maturing pine stands often 

occurs in expanding foci or pockets, 

usually initiated after thinning and 

typically increasing in size over a 

period of years (figures 1, 2). Standing 

dead trees, snags, and wind-thrown 

Figure 2. Aerial view of expanding Heterobasidion root disease pockets in a red pine plantation.
3

trees may be present in pockets, with 

unhealthy but still living trees on the 

margins. Seedlings and saplings in 

HRD pockets are often killed (figure 3). 

Tree symptoms. The health of larger 

trees with diseased roots often gradually 

deteriorates over several years. Crown 

symptoms on pines include short and 

lighter green or chlorotic needles, 

poor needle retention, and reduction 

in annual shoot growth that results in 

thin crowns (figure 4). As trees die, 

needles brown and are eventually shed. 

Colonized lower stems and roots may 

exhibit resin soaking, and clumps of 

soil infiltrated with resin may stick to 

the outside of roots (figures 5, 6). In 

the lower stems and roots, incipient 

decay may be indicated by an irregular, 

pinkish to dull-violet discoloration. 

The decay progresses to whitish pocket 

rot that sometimes includes black spots 

or flecks (figure 7). These small pockets 

in decayed wood eventually coalesce 

and reduce the roots and stem wood 

to a light-yellow to whitish, stringy 

Figure 3. Dead loblolly pine seedling growing 

near a stump colonized by Heterobasidion 

irregulare.

Figure 4. Thinning and dying crowns of loblolly 

pine affected by Heterobasidion root disease.

Figure 5. Excavated red pine root affected by 

Heterobasidion root disease, showing resinosis 

and blackening of the surrounding soil.
4

mass. This stringy decay is often seen 

in broken roots of wind-thrown trees 

(figure 8), in contrast to sharp, firmly 

splintered breaks of sound roots. 

Affected seedlings and saplings exhibit 

similar symptoms, but often die more 

rapidly.

As is the case with other conifer 

root diseases, bark beetles and other 

stem- and root-colonizing insects 

are commonly associated with trees 

affected by HRD. Such insects and 

accompanying mutualistic “stain” 

fungi are often secondary invaders of 

conifers stressed by drought or other 

unfavorable environmental conditions. 

The presence of beetle galleries, exit 

holes, frass, and their accompanying 

fungi should not be assumed to be the 

primary causes of death.

Fruiting bodies. Fruiting bodies 

(conks) are the diagnostic signs of H. 

irregulare. Conks are more common 

in some HRD pockets and scarce in 

others, and vary greatly in number 

and size from place to place and 

year to year. Increased abundance of 

conks is associated with periods of 

moist weather. Fresh conks are most 

frequently found in late summer and 

autumn in the Northeast and Midwest, 

Figure 6. Resin soaking of root wood is a 

response to colonization by Heterobasidion 

irregulare.

Figure 7. Stringy-white rot typical of advanced 

root decay by Heterobasidion irregulare.

Figure 8. Wind-thrown pine due to root decay 

by Heterobasidion irregulare.

Figure 9. Conk of Heterobasidion irregulare on 

an eastern white pine sapling.
5

and during autumn and winter in the 

Southeast (see the Biology and Ecology 

section). Several years may pass 

between initiation of an HRD pocket 

and appearance of conks.

Heterobasidion irregulare conks are 

variable in appearance, ranging in size 

and shape from very small conks that 

resemble popped popcorn, to irregular 

masses, to brackets several inches 

wide (figures 9, 10, 11). The upper 

surfaces of conks can be light gray to 

dark-grayish brown or reddish brown 

and smooth to bumpy or fissured. The 

undersurface of growing and recently 

formed conks is white to cream colored 

with tiny, round to irregularly shaped 

pores (figure 12). The light-colored 

layer often extends to the upper edge 

of actively growing conks. The under 

surface may darken to brown with age. 

Conks can be perennial, producing 

new pore layers in subsequent years, or 

annual, persisting for only a year.

Conks form on root collars and on 

trunks up to a few feet above the soil on 

living or standing dead trees, stumps, 

roots of wind-thrown trees, and slash 

of previously colonized trees. Conks 

sometimes emerge within the litter 

layer, appearing as irregular masses of 

fungal tissue with embedded needles, 

twigs, and other debris. Removal of 

this litter is often necessary to see conks 

that have grown very low on trees or 

stumps.

Figure 10. Small conks of Heterobasidion 

irregulare.

Figure 11. Large conks of Heterobasidion 

irregulare.

Figure 12. The lower surfaces of Heterobasidion 

irregulare conks contain pores that vary in size 

and shape.

Figure 13. Microscopic view of the asexual 

conidiophores of Heterobasidion irregulare with 

and without conidia.
6

Confirmation. The presence of H. 

irregulare can be confirmed in several 

ways. Although its conks are variable, 

they can be recognized by experienced 

forest pathologists and forest health 

specialists. When samples of colonized 

root or stem wood are incubated in 

moist conditions at cool temperatures 

or placed onto a semi-selective media, 

the characteristic conidiophores and 

conidia of the asexual Spiniger stage 

may form and can be viewed using 

a microscope (figure 13). Molecular 

methods are available to confirm 

H. irregulare DNA in wood samples 

extracted from lower stems and roots 

colonized by the pathogen or from 

cultures produced on growth media.

Biology and Ecology

Heterobasidion irregulare frequently 

infects conifer hosts after airborne 

basidiospores released from conks 

land on fresh wounds or stumps and 

germinate (figure 14).Infection of intact 

roots is less common, but can occur 

following percolation of spores through 

sandy soil. Basidiospore deposition 

decreases with increasing distance from 

a source and is influenced by prevailing 

winds and other environmental 

Figure 14. Diagram of Heterobasidion root disease development in a stand. Red shading represents 

tree roots and stumps infected by Heterobasidion irregulare. Basidiospores disseminated from conks 

are deposited on freshly cut stumps. After infection, the pathogen can decay the stump and roots, 

and move through colonized roots to infect adjacent trees.
7

conditions. However, detection of 

viable, windborne basidiospores of 

other Heterobasidion species many 

miles from known infestations proves 

the potential for long-distance spread. 

The period of susceptibility of conifer 

stumps to infection varies from a few 

days to up to 4 weeks after felling. 

Differences are due to tree species and 

environmental conditions that affect 

chemical and physical properties in 

the wood following harvesting, as 

well as competition from other fungi. 

After infection, the fungus decays the 

wood of the affected tree or stump. The 

fungus can grow through and along 

dying and dead roots to infect adjacent 

trees, but does not grow long distances 

through mineral soil. Multiple studies 

report growth rates in pine roots of 

up to several feet per year that vary 

depending on temperature and the 

tree species involved. The possible 

role of hardwoods and minor hosts in 

maintaining H. irregulare on sites is 

unknown. 

Midwest and Northeast Specific Information 

Because HRD has not been detected 

in large portions of the Midwest and 

Northeast that have conifer forests, there 

is increasing interest in preventing further 

infestation by H. irregulare. Fresh stumps 

produced during thinning of plantations in 

these regions are particularly important to 

initiation of HRD. After H. irregulare infects 

a stump, it may take 5 or more years before 

a pocket of mortality begins to develop 

and conks appear. HRD intensifies on sites 

through expansion of existing pockets via 

root contacts or grafts. New HRD pockets 

are also initiated following subsequent 

thinnings because inoculum spreads from 

conks on the initially colonized stumps or 

killed trees.

Basidiospores can be released any time 

viable conks are present. Extended 

periods of temperatures below freezing 

may inactivate the spore-producing layer 

of conks, so there is usually a period of 

reduced basidiospore production during 

winter. Although cold and snow cover 

restrict spore dispersal, viable spores were 

detected in heavily infested stands in 

Wisconsin, and white pine stumps were 

infected in Pennsylvania, even during the 

winter months. In both central Wisconsin 

and upstate New York, peaks of spore 

production were observed in late spring 

to early summer and again in fall and early 

winter. It is not known how the duration 

of stump susceptibility to infection might 

vary among species of northern conifers or 

under different weather conditions. 

Information is also limited regarding how 

long H. irregulare may persist at an infested 

location in the Midwest and Northeast. 

The pathogen is maintained on a site as 

new trees are infected and killed, and thus 

may be supported for as long as susceptible 

host material is present. Persistence in 

the Midwest and Northeast is likely to be 

measured in decades rather than years, 

and for this reason HRD is considered a 

“disease of the site.” 
8

Southeast Specific Information

Spore production and stump infection 

by H. irregulare are strongly affected by 

temperature in the Southeastern U.S. Below 

34° N latitude, conks and basidiospores are 

primarily produced in the fall through early 

spring. In the summer, conk production is 

inhibited and aerial basidiospores become 

scarce after daily mean temperatures are 

above 70° F. High temperatures on stump 

surfaces during summer also limit infection 

by killing basidiospores and mycelium. 

In the Southeast, damage caused by HRD is 

related to soil properties, and severe losses 

are likely if pine stands on high-hazard sites 

are thinned without preventative stump 

treatment (figure 15). Loss of loblolly and 

slash pine to HRD was found to be greater 

on sites with well-drained, sandy soils 

(sandy loam, loamy sand) at a depth of 

12 inches or greater. Medium-hazard sites 

are those that have loam or silt loams, or 

sandy soils with a clay underlying horizon 

less than 12 inches from the surface. Lowhazard soils for HRD include clay soils and 

any soil with a high water table for two or 

more months per year. 

The average yearly root spread of H. 

irregulare on a high-hazard site can range 

from 4.3 feet for loblolly pine, 3.6 feet for 

slash pine (Pinus elliottii), and 2.6 feet for 

longleaf pine. Longleaf pine mortality has 

been found to be half that of loblolly pine 

on a high-hazard site. Losses due to HRD 

occur over a 10-year period with peak 

yearly losses occurring between the 4th and 

8th year after thinning (figure 16).

Figure 15. Southeastern U.S. Heterobasidion root disease hazard rating map based on soil type and 

drainage class.
9

0 1 2 3 4 5 6 7 8 9

Years Following Thinning

Increasing Incidence/Activity

Shaded area indicates

period of anticipated

peak activity.

Increasing tree mortality

with bark beetle activity.

Declining tree

mortality without

bark beetle

activity.

H. irregulare activity

Damage (tree mortality, windthrow)

Increasing Severe Bark Beetle Episodes

Figure 16. Model of Heterobasidion root disease development, including potential interaction with 

bark beetle attack in the southeastern U.S. (Diagram from Barnard 1999)

Survey and Assessment of 

Heterobasidion Root Disease

Surveys can be used to either detect 

the presence of HRD or quantify 

the incidence and severity of this 

disease. Where HRD is considered 

less common, the primary purpose 

of surveying is detection. Surveys to 

detect HRD should focus on stands 

with evidence of root disease. This 

will appear as pockets of progressive 

tree mortality detected during stand 

examinations or using GIS or aerial 

survey data. Surveying for the presence 

of conks is the least intensive method 

to confirm presence of HRD. 

Surveys should be scheduled when 

conditions are favorable for the fungus 

to fruit. More intensive HRD survey 

methods provide greater accuracy 

on HRD incidence and severity. This 

fact was documented in a study of 

loblolly pine plantations in Virginia, 

where conks were found on only 

2.5% of survey trees, while increment 

cores and root excavation confirmed 

presence of H. irregulare in 10.1% and 

31.6% of trees, respectively. In a second 

study of loblolly pine plantations in 

Virginia, conks were found on only 

9% of trees; however, bulldozing 

the root systems revealed that 85% 

of the trees were affected by HRD. 

Systematic and intensive sampling of 

stands, including root excavation and 

laboratory processing of symptomatic 

root pieces, is used for more accurate 

surveys. Assistance from forest health 

specialists or forest pathologists may be 

necessary to identify the pathogen.
10

After the presence of H. irregulare is 

confirmed, the percentage of roots 

affected can be used to assess the 

disease impact and guide the choice 

of best management practices. An 

assay method used for decades in 

the Southeast involves excavating 

roots from each of 20 1-cubic-foot 

soil samples systematically located 

throughout a stand. Roots are 

examined for characteristic resin 

soaking or stringy white rot. The 

percentage of roots colonized by HRD 

is calculated by dividing the number of 

symptomatic roots by the total number 

of roots encountered in the 20 samples. 

Impact

The availability of information about 

the impact of HRD varies among 

regions in the Eastern U.S. Impacts in 

Southeastern pine forests have been 

well documented. The severity of tree 

mortality from HRD ranges from low 

(< 1%) to as high as 30%, depending 

on the site, environmental conditions, 

and spore load at the time of thinning. 

Radial growth loss in southern pine 

trees affected by HRD has been 

shown to range from 19 to 32% over 

5-6 years. The impact of HRD can 

increase when trees are stressed by 

suppression or drought. Southern pine 

beetle, a major pest of the South, has 

also been associated with increased 

root colonization by H. irregulare. 

Stress induced by HRD can predispose 

trees to bark beetle attack (primarily 

southern pine beetle, Ips bark beetles, 

and turpentine beetles), which can 

then result in increased losses. 

In the Midwest and Northeast, tree 

mortality and premature salvage 

of severely damaged stands have 

occurred, but adequate quantitative 

data is unavailable on growth loss, rates 

of pocket expansion, number and size 

of trees typically killed, and impact on 

wood supply.

Management of 

Heterobasidion Root Disease

The basic tools available for HRD 

management include prevention 

by protecting stump surfaces or 

restricting seasonal harvesting, and 

risk rating based on tree species and 

site characteristics. Applying these 

tools depends on many factors and 

differs among regions.

Highly effective stump surface 

treatment options include application 

of either a chemical or biological 

control agent. A borate compound 

currently available to prevent spores 

of H. irregulare from infecting cut 

stump surfaces is disodium octaborate 

tetrahydrate, or DOT. This compound 

is available as a water-soluble powder 

that can be applied manually with 

a backpack sprayer or through a 

mechanized attachment to a harvester. 

The fungus Phlebiopsis gigantea also 

has shown effectiveness as a biological 

control agent to prevent H. irregulare

colonization. If a chemical protectant 

or biological control agent is used, 

compliance with regulations for 

pesticide usage is required. 
11

Midwest and Northeast Specific Information

The primary management tools in the 

Midwest and Northeast are prevention 

of new stump infections by applying 

stump treatments or limiting thinning 

and harvests to the winter season. There 

is no absolute “safe” time period, but in 

areas with very cold or snowy winters, the 

relative risk of stump infection is reduced 

during the late winter period. 

If no HRD occurs in the vicinity, the risk 

of new infestations is greatly reduced. If 

a stand of susceptible species is infested 

but the incidence of HRD is low, or it 

is not infested but is near stands with 

HRD, there is high risk of developing 

new disease centers when cutting occurs 

without protecting stumps from infection. 

The potential impact increases if infection 

occurs early in the rotation and the disease 

has opportunity to intensify over time 

through additional entries. 

In stands where HRD incidence is 

already high, consider conversion to less 

susceptible tree species if appropriate 

for the site. Removing stumps and roots 

may reduce persistence of HRD on a site. 

However, stump and root removal will 

not prevent subsequent reinfestation if 

inoculum arrives from nearby sources. 

Land managers evaluate the need to use 

these management tools differently based 

on proximity to known infestations and 

tolerance to risk. Individual Federal, State, 

and local land management organizations 

have developed specific guidelines or 

requirements that can be consulted for 

more specific information.

Southeast Specific Information

In the Southeast, pine stands on high-hazard 

sites and eastern white pine stands have a 

high probability of significant losses from 

HRD and should be managed proactively. 

Practices to minimize losses include: 1) 

planting at wider spacing to delay and reduce 

the number of thinnings, 2) applying stump 

treatments, 3) thinning during the summer 

at sites below 34° N latitude, and 4) planting 

longleaf pine or conversion to non-hosts 

on high-hazard sites. In pine seed orchards 

or on recreational areas, stump treatment 

or stump removal should be required 

regardless of the site’s hazard rating.

Protective DOT or P. gigantea stump 

treatments are recommended for pine 

stands at risk, but not already infested by H. 

irregulare. If the percentage of roots colonized 

(as determined by cubic-foot soil assay) is 

between 10-40% in any stand, treatment 

of newly cut stumps with the biocontrol 

fungus P. gigantea is recommended. 

Unlike DOT, which only prevents surface 

infection, this fungus saprophytically grows 

into treated stumps and connected roots 

to compete with H. irregulare. Thus, P. 

gigantea can inhibit underground spread 

of H. irregulare through interconnected 

root systems to other stumps and adjacent 

trees. Another method of reducing stump 

infection is cutting during the summer 

when the mean daily temperature is above 

70° F. This summer harvest option is only 

effective south of the 34° N latitude and 

can be used when thinning pine stands on 

high-hazard sites or for sanitation cuts of 

infested stands.

Harvest and regeneration of a stand is 

recommended when the expected losses to 

HRD exceed the stumpage value, or when 

the percentage of roots colonized by H. 

irregulare (as determined by cubic-foot soil 

assay) is more than 40%. Consider a less 

susceptible species, such as longleaf pine, 

for regeneration of high-hazard sites. Sites 

with HRD can be regenerated immediately 

because seedling losses to HRD on these 

sites are typically minor and do not greatly 

affect the ultimate stocking of the stand. 
12

Assistance

Federal forest land managers can 

contact their local USDA Forest 

Service Forest Health Protection office. 

Others may contact their own State 

forest health units and universities. 

Various regional or State publications 

and Web sites, in addition to relevant 

literature listed below, may provide 

more information regarding the local 

status of HRD and specific required 

or recommended HRD management 

practices.

Relevant Literature

Alexander, S.A.; Anderson, R.L. 1985. 

How to identify and control 

annosus root rot in the South. 

Forestry Bulletin R8-FB/P 19. 

Atlanta, GA: U.S. Department 

of Agriculture, Forest Service, 

Southern Region.

Alexander, S.A.; Skelly, J.M. 1974. A 

comparison of isolation methods 

for determining the incidence of 

Fomes annosus in living loblolly 

pine. European Journal of Forest 

Pathology. 4: 33-38.

Barnard, E.L. 1999. Annosum root 

rot of pines in Florida. Florida 

Department of Agriculture 

and Consumer Services Plant 

Pathology Circular No. 398. 5 p.

Bradford, B.; Alexander, S.A.; Skelly, 

J.M. 1978a. Determination of 

growth loss of Pinus taeda L. 

caused by Heterobasidion annosus

(Fr.) Bref. European Journal of 

Forest Pathology. 8: 129-134.

Bradford, B.; Skelly, J.M.; Alexander, 

S.A. 1978b. Incidence and severity 

of annosus root rot in loblolly pine 

plantations in Virginia. European 

Journal of Forest Pathology. 8: 

135-145.

Dreaden, T.; Smith, J.; Cram, 

M.; Coyle, D. 2016. Biology, 

diagnosis, and management of 

Heterobasidion root disease of 

southern pines. Bulletin SREFFH-004. Southern Regional 

Extension Forestry. https://www.

srs.fs.usda.gov/pubs/ja/2016/

ja_2016_dreaden_002.pdf. (3 

January 2018).

Froelich, R.C.; Cowling, E.B.; 

Collicott, L.V.; Dell, T.R. 1977a. 

Fomes annosus reduces height and 

diameter growth of planted slash 

pine. Forest Science. 23: 299-306.
13

Froelich, R.C.; Kuhlman, E.G.; 

Hodges, C.S.; Weiss, M.J.; Nichols, 

J.D. 1977b. Fomes annosus root 

rot in the South: guidelines for 

prevention. Atlanta, GA: U.S. 

Department of Agriculture, 

Forest Service, Southern Forest 

Experiment Station, Southeast 

Forest Experiment Station, and 

Southeastern Area State and 

Private Forestry. 17 p.

Garbelotto, M.; Gonthier, P. 2013. 

Biology, epidemiology, and 

control of Heterobasidion species 

worldwide. Annual Review of 

Phytopathology. 51: 39-59. 

Hodges, C.S., Jr. 1974. 

Symptomatology and spread of 

Fomes annosus in southern pine 

plantation. Res. Pap. SE–114. 

Asheville, NC: U.S. Department 

of Agriculture, Forest Service, 

Southeastern Forest Experiment 

Station. 10 p.

Laflamme, G.; Bussières, G. 2017. 

Annosus root and butt rot caused 

by Heterobasidion irregulare in 

pines. Research at the Laurentian 

Forestry Centre of Natural 

Resources Canada. NRCan, CFS, 

Laurentian Forestry Centre, 

Québec, Que. 8 p. http://cfs.nrcan.

gc.ca/publications?id=37883. (3 

January 2018).

Sinclair, W.A. 1962. The root- and 

butt-rot of conifers caused by 

Fomes annosus with special 

reference to inoculum dispersal 

and control of the disease in New 

York. Doctoral thesis, Cornell 

University, September 1962. 

Microfilm #63-2799.

Stanosz, G.R.; Smith, D.; Juzwik, J. 

2016. Seasonal availability of 

inoculum of the Heterobasidion 

root disease pathogen in central 

Wisconsin. Canadian Journal of 

Forest Research. 46: 1076-1080. 

Tainter, F.H.; Baker, F.A. 1996. 

Annosum root disease. In: 

Principles of forest pathology. New 

York: John Wiley & Sons, Inc.: 

395-410.

Woodward, S.; Stenlid, J.; Karjalainen, 

R.; Hϋttermann, A., eds. 1998. 

Heterobasidion annosum: biology, 

ecology, impact and control. New 

York: CAB International. 589 p. 

(This 23-chapter book provides a 

single-source summary drawing 

from more than 2,000 research 

papers.)
14

Acknowledgments

This Forest Insect and Disease Leaflet 

replaces Annosus Root Rot in Eastern 

Conifers, which was last revised in 

1984 by Kathryn Robbins. Previous 

versions of the leaflet were written by 

H.R. Powers, Jr., and J.S. Boyce, Jr., and 

then revised by H.R. Powers, Jr., and 

C.S. Hodges, Jr., in 1970. 

The current version reflects a high 

dependence on research by a multitude 

of scientists across the Northern 

Hemisphere that has enhanced our 

understanding of this disease. Helpful 

reviews of an earlier draft of this 

manuscript were provided by James 

Jacobs, Kyoko Scanlon, Barbara 

Schultz, and Tyler Dreaden.

Image Credits:

Figures 1, 5, 9, 10, and 11: Glen Stanosz; 

Figure 2: Scott Lint, Michigan DNR; 

Figures 3, 4, 6, 7, 8, and 13: Michelle 

Cram; Figure 12: Mark Guthmiller, 

retired Wisconsin DNR; Figure 14: 

Forest Service Illustration by Juliette 

Watts; Figure 15: Forest Service Map 

by Southern Region Forest Health 

Protection. 
CAUTION: 

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html and at any USDA office or write a letter addressed to USDA and provide in the letter all 

of the information requested in the form. To request a copy of the complaint form, call (866) 

632-9992. Submit your completed form or letter to USDA by: (1) mail: U.S. Department of 

Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, 

Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov. 

Published by USDA Forest Service, Northeastern Area State and Private Forestry, 

Newtown Square, PA.

FS/NA/RO/FIDL#76-18/001