2009 Forest Health Protection and State Forestry Organizations

11.4 WEB July 2010 Management Guide for Susan K. Hagle USDA Forest Service sulphurascens (Pilat) [formerly (Murr.) Gilb. Douglas-fir form] Topics Introduction 1 Nomenclature 2

Ecology 2 Hosts: Primarily Two distinct biological species of this Impact 6 Douglas-fir occur in western North America; and grand fir one primarily on Douglas-fir and true firs Mortality rates 7 (discussed here), All may be and the other, on western redcedar (see Site factors 8 infected Chapter 13.5; Cedar Laminated Butt Rot). Assessing severity 9

Management 10 considerations A serious disease in northern Idaho and western Montana. Regeneration 11 systems This fungus kills trees in expected to have better survival on expanding patches in forests. These infested sites. Thinning 12 patches can be from a few trees to Laminated root rot is estimated Prescribed fire 14 many acres in size. Trees of all ages to infest at least 739,000 acres in Fertilization 14 are killed as their roots are Idaho and Montana. Mortality destroyed by the fungus. Many also centers occupy over 15,000 acres of Biological control 14 die through wind-throw following federal, state and private forestland Stump removal 15 decay of support roots. The fungus on and near the Idaho Panhandle, Chemical control 15 spreads underground through tree Clearwater, Lolo, Kootenai and root systems and survives for many northwestern Bitterroot National Other reading 16 decades in dead roots and stumps. Forests in Idaho and Montana. It is Field Guide Laminated root rot should be rarely seen south of the Salmon Management Guide considered a “disease of the site”. River in Idaho. Douglas-fir and Index That is, established mycelia of this grand fir forests on warm, moist site fungus are essentially permanent, so types are most damaged. the best course is to minimize losses Key Points by managing tree species that can be  Manage for pines, larch, and cedar.

 Precommercial thinning may OVERVIEW OF improve growth and LAMINATED ROOT ROT MANAGEMENT survival of pines and larch 1. Favor resistant species. Especially pines and western larch.

 Thinning for bark 2. Thin early and avoid partial harvests. Precommercially thin beetle control may favoring root disease resistant species. result in increased 3. Avoid commercial thinning that will leave susceptible mortality if crop trees. Mortality rates of susceptible leave-trees are likely laminated root rot to remain high, or increase following thinning. is present.

Page 2 Back to menu Laminated Root Rot 11.4

Nomenclature of The name Phellinus Banik and others (1993) found sulphurascens was officially Douglas-fir isolates to be distinct Laminated root assigned to the Douglas-fir/ true fir from the cedar form in ELISA rot in Western form of Phellinus weirii by Larsen (seriological) tests. They also North America and others in 1994. But at least as demonstrated that the Douglas-fir by far back as 1954 the two distinct form is serologically related to Thies and forms of Phellinus weirii, one Siberian isolates of P. Sturrock, 1995 found primarily on Douglas-fir and sulphurascens. It is more closely the other in western redcedar, were related to the Asian P. This useful recognized (Buckland 1954). The sulphurascens than to cedar form publication provides name change will reduce the isolates of P. weirii. They excellent confusion that has resulted from concluded that the Douglas-fir form photographs and using the same name for two is probably conspecific with P. summarizes the dissimilar fungus species, with sulphurascens. Based on results relevant information different hosts, and vastly different from monocaryon matings, Larsen for the identification and management disease management methods. and others (1994) also concluded of this disease. Larsen and Lombard initially that the correct name for the proposed separation of the cedar Douglas-fir form is Phellinus form from the Douglas-fir form sulphurascens Pilat. They also into two distinct species in 1989. described the hyphal system of They found significant differences both Douglas-fir and cedar forms in cultural characteristics, length of as being monomitic. A monomitic setal hyphae, basidiospore hyphal system is the principle germinating characteristics and criterion that separates the host specificity. Cedar and Douglas Inonotus from Phellinus. Therefore Phellinus -fir forms are distinctly intersterile the correct generic placement of sulphurascens groups in culture (Angwin and both P. weirii and P. sulphurascens Hansen 1988). Despite finding is Inonotus.  Pathogen of nearly complete genetic isolation of Beginning in 2007 Sturrock and conifers in the Douglas-fir and cedar forms associates adopted the use of northern Angwin (1989) recommended Phellinus sulphurascens to refer to hemisphere. considering them to be intersterility the Douglas-fir form (Sturrock and  Annual groups rather than distinct species. others 2007, Lim and others 2008). sporophore Intersterility observed in cultures This is the binomial I will use in was confirmed by Bae and others the present document.  Douglas-fir and (1994) in naturally-occurring grand fir are the populations. most important hosts. Ecology of laminated root rot in forest ecosystems  Does not mate with Phellinus Life Cycle summer or fall. The simple, single weirii. Phellinus sulphurascens begins -celled spores are produced en life, like most fungi, as a spore. masse within pores of the  Monomitic The mostly annual, crust-like sporophore. They are wind or hyphal system sporophores typically form on the water-dispersed; rarely landing on suggests genus name Inonotus. moist underside of downed logs. a substrate that is suitable for their The sporophore matures in late survival. 11.4 Back to menu Laminated Root Rot Page 3

Moisture is required for Oregon was estimated by Dickman germination. The mycelium that is and Cook (1989) to be at least 460 subsequently produced must years old. Laminated root establish on suitable wood and Saprophytic and parasitic rot is commonly repel competitors or perish. Most existence found in the perish. Phellinus sulphurascens has same trees and been reported to live even the same Persistent and expanding saprophytically in the roots and roots with other mycelial clones lower stem of fallen trees or in root diseases New myclia from germinating individual cut stumps for as long such as spores probably join with, and as 50 years (Hansen 1976, 1979a). Armillaria, exchange nuclei (conjugate) with Hyphae penetrate the wood, other mycelia to become Annosus, and causing a ‘white rot” type of decay Tomentosus root heterokaryotic. These mycelia may in which both cellulose and lignin diseases. have ecological advantages over are degraded. Dead wood utilized those grown from a single spore by P. sulphurascens also may be Angwin and Hansen (1993). Even from tree and woody-shrub species so, life is precarious for the new that were resistant when they are heterokaryote and few will live to alive. establish as a clone. The mycelium spreads from There is little genetic variation woody substrates to the roots of within established clones, live trees through direct root indicating that they start from contact with infected wood. Mycelium— single basidiospores and do not Infection intensity may increase Plural: Mycelia mate with or combine genetic with each generation (Tkacz and The vegetative (non- material with new spores or fruiting) part of a fungus Hansen 1982). In northern Rocky consisting of a mass of colonies (Bae and others 1994). Mountain forests, Douglas-fir and branching, thread-like Vegetative incompatability among grand fir are particularly hyphae. clones effectively prevents susceptible to infection. Once initiation of new infections in Monomitic— established on a root of a live tree, a fungus that has only areas occupied by established the fungus invades and kills the one kind of hyphae, clones (Bae and others 1994). This cambium of the root and the generative hyphae. means that established clones decays the dead root tissues. The effectively block invasion by new Heterokaryotic— mycelium may eventually travel cells having two distinct clones of P. sulphurascens. It up the root to colonize the root nuclei. Generally appears that once a clone is collar, and girdle the tree. produced by conjugation of two different mycelia. established on a site, it may survive for centuries by utilizing Aggregated and dispersed Homokaryotic— both living hosts and dead infections in stands cells having one substrates. Generation after Laminated root rot occurs in nucleus. Homokaryotic mycelia generally result generation of trees serve as hosts complex patterns in forest stands, for the same clone on a site. from germination of with many or most of the infected sexually produced Because clones within trees bearing no above-ground spores, such as those infection centers are genetically symptoms of infection. Distinct from sporophores. distinct from one another, the infection centers are easily approximate extent and age of detected as aggregations of dead clones associated with some and diseased trees. Much of the infection centers have been infection in a stand will be within determined. For example, a clone and adjacent to these infection in a mountain hemlock forest in centers.

Page 4 Back to menu Laminated Root Rot 11.4

Infected trees also are found The most significant effect of dispersed throughout stands in fire may be the opportunity it locations having no apparent provides for less-susceptible tree relationship to infection centers species to establish. Pines and larch (Thies and Nelson 1997, Thies and are sometimes able to survive fires Sturrock 1995). Thies and Nelson that kill Douglas-fir and grand fir, (1997) reported that infection rates and to take advantage of fire- at considerable distance from produced openings to regenerate. infection centers were as high as Historically, fires probably played they were at the edges of infection an important role in reducing EXPANSION RATES centers, near confirmed inoculum laminated root rot by favoring sources. disease-resistant tree species. Bloomberg (1990) monitored the rate of “In most stands, the pattern of [P. expansion of 62 Forest structure and composition sulphurascens] infection was diffuse laminated root rot effects of laminated root rot rather then distinctly aggregated, centers, for 27 years, in and in no case did openings As previously discussed, P. three coastal Douglas- accurately portray the distribution sulphurascens infections are both fir plantations in British of the disease.” Thies and Nelson Columbia, Canada. dispersed and aggregated in stands. 1997 However, most mortality occurs The overall average rate Trees that were expected to be where infections are aggregated, of expansion was unimpressive: 1-8 cm/ infected based on proximity to also known as “infection centers”. yr. Roughly 0.5 to 4 known inoculum sources (within 5 As overstory trees are killed in inches per year. m) and having symptomatic infection centers, openings in the crowns (poor growth, thin crowns, forest canopy result. This produces This was because most of the perimeter of an chlorosis) were, in fact, no more a characteristically patchy forest infection center had no likely to be infected than trees that structure. Canopy openings provide change at all in most grew far from known inoculum opportunities for years. sources and had healthy-appearing regeneration, and growth of woody

However, where crowns (31% of the former shrubs and forbs. These openings expansion did occur, the compared to 29% of the latter). increase structural diversity, and average rates were The dispersed infections may sometimes species diversity, in a impressive: ranging forest. (Holah and others 1993, from 54 to 63 cm/yr. eventually become the focus of Roughly 27 to 31 new infection centers (Thies and Holah and others 1997). After inches per year. Nelson 1997). timber harvest, some vegetation differences between former gaps Fire and previously intact forest persist Fire has historically been an (Ingersoll and others 1996). important factor in shaping forest composition and structure in the Timber harvest northern Rocky Mountains. Based Following harvest, Phellinus on the considerable age achieved sulphurascens readily infects the by Phellinus sulphurascens clones, subsequent regeneration of it is reasonable to conclude that susceptible trees. Although rapid they typically survive forest fires. and nearly complete mortality of They may be fragmented by partial Douglas-fir regeneration, due to destruction of the mycelium or by laminated root rot, has been exhaustion of substrate in spots, reported (Ingersoll and others but regeneration and growth of 1996), this is not usually the case. suitable hosts has the effect of allowing re-expansion of clones. 11.4 Back to menu Laminated Root Rot Page 5

In fact, Armillaria ostoyae is often Mortality wave patterns on the more aggressive pathogen in harvested sites the first two decades after timber The primary difference The wave phenomenon harvest (Bloomberg 1990, Thies between the wave pattern in root was described by and Sturrock 1995). In northern disease infected stands on sites Dickman and Cook Idaho and western Montana, with no cutting history and that on (1989) as “outwardly- stands regenerated after a harvest sites that have been cut is that the spreading rings within are usually 25-40 years old by the harvest sets the timing of the first rings.” time laminated root rot begins wave by stimulating the causing more mortality than regeneration that will reach pole Armillaria root disease. size at about the same time. Primary spread from stumps Temporal patterns of mortality results in new infections in these and re-growth: wave pattern young trees. As in the uncut stand, WAVE PATTERN Patches of laminated root rot the young trees die a few at a time exhibit slow expansion into until the survivors are large As a result of the surrounding forest; a rate of about enough to provide a substantial temporal pattern one foot per year (Thies and food base for the fungus. At this of tree death and Sturrock 1995). In addition to point, secondary spread will subsequent expansion at the perimeter of accelerate the rate of mortality. As regeneration, patches, trees within the disease trees die, they are replaced by ranks of trees of patch regenerate, grow and die in a abundant regeneration. Mortality similar ages are pattern described by Dickman and then slows until sufficiently large observed in Cook (1989) as waves of infection. root systems have been produced concentric circles. The initial mortality wave to fuel another wave of mortality. occurs as the pathogen moves Recognizable root disease patches Recognizing this outward along the margins of the eventually re-emerge in cutover pattern in stands disease patch into the non-diseased stands as groups of trees are killed will aid in portion of the stand. The resulting and openings are regenerated. identifying the canopy opening is eventually filled extent of an with tree seedlings. When this new Dispense with the vigor myth infection center. cohort of trees contacts inoculum Contrary to popular belief, from infected roots from the superior vigor does not confer previous stand, they in turn are improved resistance of Douglas-fir killed; the second wave of to laminated root rot. Hansen and mortality. Goheen (2000) refer to this as “the Subsequent waves follow as widespread but false belief that new cohorts of trees regenerate, pathogens in natural ecosystems THE VIGOR MYTH: reach enough biomass to fuel a only kill weakened trees”. In pulse of fungal growth, and die to reality, faster growing trees have The widespread but once again open the canopy. The an equal or somewhat higher false belief that result is a stand with zones probability of dying from pathogens in representing the temporal laminated root rot compared to natural ecosystems sequence of root disease slower growing trees (Miller and only kill weakened development in the stand. These others 2006) This is probably just trees (Hansen and zones form concentric rings from a matter of their larger root Goheen 2000). the center of the disease-affected systems contacting more area to the perimeter. inoculum.

Page 6 Back to menu Laminated Root Rot 11.4

Impact of laminated root rot on forest productivity On sites where a mature stand with Infection rates radial increment in infected trees laminated root rot Although nearly all conifers lasting 30 years or more before has been harvested, Armillaria root are occasionally infected, Douglas death in mature Douglas-fir. disease often -fir, mountain hemlock, grand fir Smaller trees typically had shorter becomes the primary and white fir are most susceptible detectable periods of decline pathogen in young conifers that (Hansen and Goheen 2000). In the before death. The longer the regenerate following northern Rockies, Douglas-fir and period of decline before death, the harvest. grand fir are the most common greater is the cumulative growth hosts. loss. Diameter growth is more It may take several decades for The disease is best known and affected by laminated root rot than laminated root rot to probably most damaging in coastal height growth in coastal Douglas- again become the Douglas-fir forests of Oregon, fir (Harrington and Thies 2007). most prevalent Washington and . As expected, trees with the highest disease. Surveys indicate that 8.6% of the rates of root decay exhibit the Douglas-fir forest area in western largest declines in growth. Oregon is occupied by laminated root rot centers in which half of Mortality the Douglas-fir have been killed In coastal forests, grand fir is (Hansen and Goheen 2000). The the most susceptible species, disease is present in 80% of followed by Douglas-fir (Table 1). INFECTION DETECTION second-growth Douglas-fir stands Nelson and Sturrock (1993) Ectotrophic mycelium on Vancouver Island, British measured grand fir mortality rates Columbia (Bloomberg and averaging about 31% in 17-20 Reynolds 1985). years for trees planted around A recent analysis in Idaho and infected stumps in coastal Oregon Montana, estimated that 739,000 and British Columbia. Rates for acres are infested with this disease. coastal Douglas-fir averaged about Of these, 156,000 acres have 26%. Western hemlock and mortality rates of at least 25% of ponderosa pine had moderate the basal area every 15 years. mortality rates of 12% and 11%, Large canopy gaps, with over 75 repectively. Other pines and percent canopy loss caused by western redcedar mortality rates laminated root rot occupy 15,400 lowest, around 5%. acres of the most productive forest Similar rates of mortality were Thies and Nelson land types in these two states. measured in inland forests on (1997) found that the randomly-placed plots. In this presence of ectotrophic mycelium identified 82 Growth decline case, Douglas-fir had the higher percent of the infected Decay and girdling can be mortality rate compared to grand trees in a mature stand. slow processes and considerable fir. A net loss in basal area of 35% infection can develop in root for Douglas-fir and 20% for Wallis and Bloomberg (1981) found that only systems before trees begin grand fir was measured. The plots, half of the infected showing obvious crown in northern Idaho, monitored trees Douglas-fir trees 25 to symptoms. The first symptom to that were at least 5 inches dbh, at 60 years of age have above-ground develop is usually growth decline. the start of the study, over a 20- symptoms. The cumulative growth depends year period (Hagle, in on the age of trees. Bloomberg and preparation). Wallis (1979) detected reduced 11.4 Back to menu Laminated Root Rot Page 7

Perhaps the relative rates of grand fir. This may suggest similar mortality can be inferred from a mortality rates for these two survey reported by Filip and species; but the relatively longer Schmitt (1979). They selected needle retention of dead grand fir locations with at least 15% could give a false impression of a mortality and Phellinus as the higher mortality rate. primary cause. They found 20% of the Douglas-fir dead and 23% of

Table 1. Relative susceptibility to Phellinus sulphurascens in the northern Rockies . Reported mortality Species Susceptibility On northern Rocky Mountain sites rates (infested sites) High 35% /20 yrs ID1 This is the most damaged species in the Rocky Mountain 20% E. OR/WA2 and west coast portions of the range of laminated root rot 26% /17-20 yrs Coastal3 in North America. Both coastal and inland varieties of Douglas-fir are highly susceptible. Grand fir High 20% /20 yrs ID Grand fir is very susceptible to infection but dies 23% E. OR/WA somewhat more slowly than Douglas-fir. 31%/17-20 yrs Coastal Subalpine fir High 43% /20 yrs ID Subalpine fir can be very susceptible when growing in association with grand fir on the warm/ moist end of the range of subalpine fir. Cold and dry habitats appear to inhibit development of the disease. Mountain High 32% E. OR/WA We know little about root diseases in this species in the Hemlock northern Rocky Mountains but it is considered highly susceptible on the eastern slopes of the Cascades. Western larch Moderate 6%/20 yrs ID Damage is uncommon, usually occurring in older, 27% E. OR/WA unthrifty, trees growing with Douglas-fir or grand fir. Western Moderate 4% /20 yrs ID We rarely see significant damage in this species in inland hemlock 12%/17-20 yrs Coastal stands. Western Low >1%/20 yrs ID Western redcedar is reported as either immune or highly redcedar 5%/17-20 yrs Coastal tolerant. Ponderosa pine Low >1%/20 yrs ID Damage is rare in this species; has been observed in 11%/17-20 yrs Coastal individuals growing with Douglas-fir and grand fir. Lodgepole Low >1%/20 yrs ID Damage is rare, usually occurring in older, unthrifty, trees pine 9% E. OR/WA growing with Douglas-fir and grand fir. 5%/17-20 yrs Coastal Western white Low >1%/20 yrs ID Damage is rare but has been observed in older trees. pine 5%/17-20 yrs Coastal Engelmann Low Insufficient data Damage is rare; usually occurring in trees grown with spruce Douglas-fir and grand fir. 1 Percent of trees killed in 20 years with Phellinus as an identified cause; on permanent plots that had known Phellinus inoculum within 30 feet (Unpublished data, Hagle 2008.) Plots are in northern Idaho. 2 Percent of trees that were dead at the time of the survey; stands were east of the Cascade range in Oregon and Washington (Filip and Schmitt 1979.) Plots were selected on the basis of having at least 15% mortality with Phellinus as the primary cause. 3 Percent of trees killed in 17-20 yrs in plots with known Phellinus infection; coastal forests of Oregon and British Columbia (Nelson & Sturrock 1993.)

Page 8 Back to menu Laminated Root Rot 11.4 Sites that are prone to laminated root rot in Idaho and Montana Laminated root rot causes Western hemlock and grand fir problems on a narrower range of PVTs had the highest constancy habitat types than do Armillaria or Laminated and highest severity of laminated Annosus root diseases. Cool, moist root rot in 312 randomly placed root rot types typified by western hemlock permanent plots in the Coeur

potential vegetation type (PVT) d’Alene Basin of northern Idaho Is found mostly and warm moist habitats with (Figure 1). Of 73 plots in western on western grand fir PVT make up the hemlock PVT group, 62% had hemlock or grand majority of the infested sites. confirmed laminated root rot. Of fir potential Likewise, a high proportion of 88 plots with grand fir PVTs 54% vegetation types. these PVTs may be infested by had the disease (Hagle, this pathogen within it’s range. unpublished.) Overall, 48% of the Byler and others (1990) found 312 plots had laminated root rot. sites on the Lolo NF in western In contrast Douglas-fir PVT plots

70 61.6 60 Western Montana 53.9

Frequency of 50 Phellinus sulphurascens by 40 habitat types on the 26.5 Lolo National Forest: 30 [Byler and others 20 1990]

10 Western hemlock 0 0 PVT— 87% Percent of Plots Infected 0 Douglas- Grand fir Western Western Subalpine Grand fir PVT— fir PVT redcedar hemlock fir 17% PVT PVT PVT PVT

Western redcedar PVT— 11% Figure 1. Percent of 312 plots with confirmed laminated root rot within five sampled habitat type groups. [Coeur d’Alene Basin, Hagle 2008 unpublished.]

Douglas-fir PVT— 4% Montana on western hemlock PVT had a lower than average to have far higher probability of probability of infection, only 26%. laminated root rot than other sites. None of the 13 western redcedar They found the pathogen on seven PVT plots showed infection, but of eight stands (87%) sampled in they all had redcedar forest this PVT group compared to the composition, a resistant tree second highest, 17% of 106 species. Only four plots with samples, in grand fir PVTs. In subalpine fir PVTs were sampled contrast, they detected laminated and none had evidence of P. root rot on only 4% of the sample surphurascens infection. The in Douglas-fir habitat types and pathogen has been observed on 11% in western redcedar habitat subalpine fir habitats, as well as on types. this host, but not often. 11.4 Back to menu Laminated Root Rot Page 9

Assessing Laminated Root Rot Disease intensity on infested sites Root Disease Severity Rating grand fir regeneration in these Root disease severity is a openings seldom reaches maturity. measure of the cumulative impact However, if disease-resistant ROOT DISEASE of root disease in a stand or on a species, western hemlock and SEVERITY CLASSES site. It is visually rated based on western redcedar in particular, relative effect of root disease on establish in the openings, they are 0 —No evidence of forest canopy density (see likely to survive and eventually root disease. sidebar). At the most severe end of return the forest canopy to full the scale, no trees of the original closure. Low—Ranges from overstory remain alive. At the low Figure 2 illustrates the minor evidence up to end of the scale, little evidence of relatively greater severity of root 20 percent canopy the disease will be seen and little disease impact with laminated root reduction. or no canopy loss will have rot compared to other root diseases Moderate—Between occurred. Laminated root rot is on permanent plots in northern 20 and 75 percent more likely to cause severe loss of Idaho. The proportion of plots loss of canopy. forest cover than are the other falling in the highest disease major root diseases in northern severity levels was nearly double High— at least 75 Idaho and west-central Montana. compared to all plots. A similar percent loss of Loss of forest cover, or canopy trend was found in permanent canopy. is reflected in the site root disease plots on the Kootenai NF in [Guidelines for rating root severity (Hagle 1993). Disease Montana. Phellinus sulphurascens disease severity: see Hagle severity can be assessed using was seldom the only root pathogen 1993 or on the web Hagle 2009.] aerial photography or on the detected on a plot, with Armillaria ground. It is a rapid and efficient ostoyae or Heterobasidion method to assess the relative annosum commonly also present. impact of the disease on a site and to predict future impacts (Hagle and others 1992, Hagle 1993, 25% Hagle 2000). In 312 permanent plots in 20% northern Idaho, monitored for 18 to 24 years, root disease severity assigned at the beginning of the 15% monitoring period was the best 10% predictor of tree mortality over the Percent of plots entire period. Severity was a highly significant indicator (P= 5% >.0001) for subsequent Douglas- fir mortality, in particular. 0% At the highest levels of disease 0 Low Moderate High severity, stands commonly have only a few surviving trees by 80 to All plots Phellinus-infected 100 years of age. Large openings in the tree canopy permit growth Figure 2. Distribution of root disease severities among 213 plots (all plots) of shrubs, forbs, and conifer compared to 102 plots with confirmed Phellinus sulphurascens (Phellinus- regeneration. Douglas-fir and infected.) Coeur d’Alene Basin, Idaho Panhandle NF

Page 10 Back to menu Laminated Root Rot 11.4

However, the presence of P. often concentrated in discrete sulphurascens was significantly infection centers. See Thies and associated with more severe root Sturrock (1995) for more disease. information.

Surveying stands for location Stump survey and size of infection centers After harvest, cut stump Most of the laminated root surfaces can be examined for The characteristic brown disease in a replacement stand will symptoms of laminated root rot. A stain in the sapwood of recently cut stumps is used be where it occurred in the portion of the stumps with infected to identify many of the previous stand. Before stand roots will have decay or stain harvest, openings or gaps caused visible at the stump surface. The by root disease are easily locations and number of visibly observed. These infection centers infested stumps are a good Mechanisms of can be mapped by walking parallel indicator of the biomass of the root spread transects and marking the pathogen on the site (Thies and

Thies and Westlind beginning and end of each Westlind 2006). Such information (2005) recently infection center using GPS (or a can be used to direct planting of concluded that there sketch map). This method is disease resistant trees or other is “a need to examine especially appropriate in coastal efforts to reduce damage in the more closely the epidemiology of forests where the disease is more replacement stand. laminated root rot.

...the infection Considerations for managing laminated root rot process is more complex and needs to Some important characteristics declines, so will the fungus be better of laminated root rot to considered biomass. understood.” for management of the disease 4) The effective host range include: (species on which the fungus Root to root spread has long been the accepted can build biomass) is limited. model for laminated root 1) Laminated root rot is a ‘disease 5) The pathogen is probably rot and fits most field of the site’ because the naturally limited by competing observations of the pathogen , Phellinus fungi, especially saprophytic disease. However several recent sulphurascens. persists on a species that are capable of discoveries seem site from one generation of growing rapidly in dead wood. inconsistent with this trees to the next. 6) The pathogen is rarely mechanism of spread. 2) The fungus is both an efficient successful in establishing new parasite and saprophyte, infection centers so Thies and Westlind cite: meaning that both live and infestations are fairly stable. 1. scattered infected dead wood is utilized by the 7) Scattered infections, trees, fungus. unassociated with disease 2. the appearance of laminated root rot in 3) The fungus biomass on a site is centers, on roots of apparently replacement stands limited by the biomass of host healthy trees, are common. where it had not been tissue. So if there is an This probably accounts for the present before harvest, abundance of large host trees, disease appearing in locations and, 3. nearly a third of plots the fungus can achieve very in replacement stands which that had laminated root large biomass on a site were judged to be disease-free rot before harvest, sufficient for survival for many in the previous stand. having no disease-killed decades, perhaps hundreds of 8) Laminated root rot is rarely the trees in the replacement stand. years after the host has died. only root disease present in However, if host biomass stands in Idaho and Montana. 11.4 Back to menu Laminated Root Rot Page 11

Managing laminated root rot

Management objectives will Methods for managing BOTTOM LINE guide the choice of methods to be laminated root rot fall into two categories, silvicultural control of used, but it is also important to Root disease is damage and direct inoculum consider the presence of root permanent disease when developing the removal. Silvicultural methods for objectives for a stand or group of managing root diseases are nearly You may be able stands. Established root pathogens always more successful and cost- to reduce the can be as limiting as other features effective than are chemical mass of the that determine site capability such fumigation or physical removal of fungus but you as latitude and altitude, soils, inoculum. However, for high- won’t eliminate it. moisture regimes, and exposure. value trees there is some indication Realistic management objectives that chemical fumigation can rid Usually, you will need to change live trees of infections. Inoculum will take into account the tree composition laminated root rot considerations removal by de-stumping infested to more resistant outlined in the previous section. sites also may have some species. applicability.

Silvicultural control methods Regeneration Systems Shelterwood or uneven-aged Armillaria and annosus root systems should be avoided diseases are commonly found on because they usually result in too sites that have laminated root rot. much Douglas-fir, grand fir or Fortunately, silvicultural control subalpine fir regeneration. Disease methods used to manage laminated intensification in partially- root rot should be equally effective harvested stands appears to be due against these other major root to the rapid colonization of the pathogens of Douglas-fir and true stumps and roots after infected firs. trees are cut. Infested stumps then Even-aged silvicultural serve as effective food bases for Western larch (above) and systems, are aimed at producing a ponderosa pine (below) the pathogens enabling them to seed-trees are used to replacement stand that is better infect and kill other nearby trees. regenerate root disease suited to resist or tolerate Western redcedar, normally infested sites. laminated root rot. Whether considered a root disease-tolerant clearcut or seedtree methods are species, may develop a progressive used, the target replacement stand decline after a partial harvest. If should be comprised of less than western redcedar is an important one-third Douglas-fir and grand fir component of the residual stand, it (combined). Pines (western white, would be prudent to avoid ponderosa and lodgepole), western removing more than about one larch, Engelmann spruce and third of the overstory canopy to western redcedar are good choices minimize risk of Armillaria root for disease-resistance. Mixed- disease losses in the residual species stands are nearly always cedar. This does not apply to more resilient than single-species western redcedar that regenerates stands. after the harvest.

Page 12 Back to menu Laminated Root Rot 11.4

Utilization of stumps by P. Commercial thinning sulphurascens is about the same Impacts of root diseases whether the stand is clearcut or following commercial thinning, partially harvested. What makes like other partial harvests, mostly the difference in subsequent depends on the composition of the impact is the composition of the residual stand. As discussed with stand on the site following harvest. respect to shelterwood and uneven Therefore, when possible, resistant -aged systems, higher rates of or disease-tolerant species should mortality in residual Douglas-fir be favored when harvesting in root and grand fir can be expected -disease afflicted stands. Douglas- (figure 3). To minimize the effects fir and grand fir often die within a of mortality and, perhaps, slow the few years after thinning, having spread of the disease, reduce produced little or no additional Douglas-fir and grand fir to less growth. Douglas-fir and grand fir than one third of the basal area. left as shelterwood or seed or crop Even so, you can expect high rates Photo above shows uneven- aged stands often provide trees, are likely to exhibit rates of of mortality in residual Douglas-fir ideal habitat for root mortality around 30 to 40 percent and grand fir. pathogens as Douglas-fir and per decade following a partial grand fir regenerate in partial shade. harvest (figure 3).

Figure 3. The rates of mortality in commercially thinned (filled symbols) compared to unthinned (hollow symbols) Douglas-fir and grand fir stands. The already-high rate of mortality of Douglas-fir was increased somewhat by thinning. Grand fir mortality was much higher in the thinned stands compared to those left unthinned. The stands have a combination of laminated, Armillaria and annosus root diseases . 11.4 Back to menu Laminated Root Rot Page 13

Removals for bark beetle control grand fir in a stand in the first Douglas-fir beetle decade after thinning. After a (Dendroctonus pseudotsugae), fir decade or so of poor growth, and engraver beetle (Scolytus high mortality rates, the residual ventralis) and western balsam bark stand volume often is so low as to beetle (Dryocoetes confusus) are render a regeneration harvest no all associated to some extent with longer economically feasible. root disease-weakened trees. In most cases, they can utilize Precommercial thinning can be weakened trees to maintain used to push the stand species Tree Resistance endemic populations. Epidemic composition toward disease populations are not so closely tied resistant or tolerant species, Necrophylactic periderms in roots to weakened trees and may attack especially western larch and pines. produced in response to many healthy trees. If possible, a reduction of the injury or infection. Trees combined composition of Douglas may produce several Removal of attacked trees -fir and grand fir to less than one successive Root pathogens almost third will minimize laminated root necrophylactic certainly utilize the roots of bark rot impact. By maturity such periderms as each previous periderm is beetle-killed trees in much the stands are likely to have even less breached. same way they use stumps of Douglas-fir and grand fir and root harvested trees. Efforts to control pathogen biomass should be fairly Most lesions are halted bark beetles by removing beetle- low. by defense chemicals infested material from the woods Laminated root rot can be (phenolic compounds) in may be of benefit in controlling problematic in western larch. the bark or cambium of roots. If prevented from the beetle populations and would Observation suggests that most of expanding long enough, be unlikely to increase root disease the problem occurs in poor periderm-surrounded impacts. The roots of killed trees growing trees. Periods of crowding infections will eventually would be utilized by the fungus or severe dwarf mistletoe infection be sloughed (as the root whether the stem was removed or may compromise the natural grows) and the root will not. resistance of western larch to root heal. infections. Precommercial thinning Bark beetle prevention thinning can enhance resistance of western Thinning to reduce stand larch by maintaining the tree’s density and thereby reducing the ability to produce phenols and attractiveness of a stand to bark necrophylactic periderm to limit beetles is, in effect, a commercial the spread of P. sulphurascens thinning. If the species infections. Larch dwarf mistletoe composition of the residual stand infection levels can also be can be shifted by thinning to leave reduced by selective removal of mostly disease resistant species, it obviously infected trees during will benefit both beetle and root precommercial thinning. For other disease management. strategies to reduce dwarf If most of the after-thinning mistletoe infection, see Hoffman stand will be Douglas-fir and true (2004). firs, laminated root rot and other If the disease severity is root diseases can be expected to moderate or higher, increase. The increase in mortality precommercial thinning leaving is fairly rapid, more than doubling Douglas-fir crop trees may be un- rate of mortality in 10 years, to economical because of poor kill over half the Douglas-fir and subsequent survival.

Page 14 Back to menu Laminated Root Rot 11.4

Mortality rates of Douglas-fir adjacent to the burn-treated area. remain about the same whether Be prepared for a short flush of stands are precommercially thinned bark beetle mortality in fire- or not and growth response of this damaged trees. species is both minimal and temporary. Fertilization Improvements in Douglas-fir Management by fire growth may (Miller and others Fire can be very effective in 2004) or may not (Nelson and creating large mosaics typical of others 1994) be realized through the natural fire patterns on habitats nitrogen and potassium where laminated root rot is fertilization. However, laminated Photo shows fire is an prevalent. The outcome with root rot mortality is unaffected by important natural control for root disease by favoring respect to laminated root rot will fertilization (Thies and Westlind the survival and depend on the species that are 2005, Miller and others 2006). regeneration of pines and western larch. regenerated. Burning does not harm Fertilization of Douglas-fir with Phellinus sulphurascens nor the nitrogen alone may increase the other major root pathogens because probability of Armillaria root they reside well below ground. disease-cause death (Moore and The roots of trees killed or others 2004). Faster growing trees damaged by fire will be utilized by are likely to contact more root pathogens to increase biomass inoculum which may increase and spread to the residual trees and mortality rates relative to slower regeneration. So, like a growing trees (Miller and others regeneration harvest, expect higher 2006) mortality rates among residuals and (Continued on page 15)

Saprophytic fungi such as Antrodia heteromorpha (shown on a Douglas-fir Managing laminated root rot: Biological control stump above and below) Antagonistic fungi have been used death or harvest. These organisms quickly establish on stumps and dead trees and successfully as biological have the potential to limit the effectively exclude root pesticides in forest nurseries and in development of root disease fungi. pathogens from the resource. They probably play other agricultural settings. A Among the most common fungi an important role in limiting common mold-type fungus, seen fruiting on stumps and snags the buildup of root diseases on harvested or burned Trichoderma viride Pers., is an in the northern rockies are sites. aggressive fungal antagonist in Fomitopsis pinicola (Swartz:Fr.) culture (Nelson 1964). When Karst., Trichaptum abietinum inoculated in holes drilled into (Dicks.:Fr.) Ryv., Gloeophyllum Phellinus-infested stumps, T. sepiarium (Fr.) Karst., and viride was successful in killing Antrodia heteromorpha (Fr.) Donk. Phellinus near the inoculated sites In addition, several are routinely (Nelson and Thies 1985, 1986). isolated from dead roots of trees, in Unfortunately, Trichoderma had particular Perenniporia subacida limited ability to penetrate the (Pk.) Donk, F. pinicola, Resinicium woody substrate, which limited the bicolor (Alb.& Schw. ex Fr.) Parm. its ability to interact directly with and T. abietinum. These fungi the root pathogen. probably naturally control Many other naturally- laminated root rot and other root occurring saprophytic fungi invade diseases to some extent by conifer roots shortly after tree competing for woody substrates. 11.4 Back to menu Laminated Root Rot Page 15

Managing laminated root rot: Direct Inoculum Removal

(Continued from page 14) mortality by over half in the first The amount of inoculum in the two decades after site regeneration soil significantly influences the (with Douglas-fir) in coastal transmission and subsequent forests (Morrison and others 1988, disease severity in the regenerated Thies and others 1994). Perhaps a stand (Miller and others 2006). third of the treated area had no Methods and results of reducing laminated root rot. Infected stumps ISOLATING THE the biomass of pathogen inoculum are identified by the presence of INFESTED AREA has been studied extensively in stain or decay at the stump surface. western coastal Douglas-fir forests All infected stumps are removed where site values are high and along with as much of the root alternative tree species have much system as possible. lower timber value and productivity (Thies and Sturrock Isolating the infested area 1995). Lateral expansion of root disease centers may be halted or Stumps were removed to Root removal slowed by removing root systems restrict spread of the root Stump and root removal can be in a buffer surrounding an pathogen at the margin of the infection center (at left accomplished either by digging infection center. Although the in the above photo). All out the stump and roots after the infection center itself is still stumps were removed and wind-rowed in a 200-foot harvest or by push-falling trees unsuitable for growing Douglas-fir buffer (see photo below). and then raking the roots from the and grand fir, it is somewhat This control effort was soil. An excavator is used for contained in this way. Bear in implemented on industrial forest land in Montana to digging out stumps and roots and mind that some infections will be control Armillaria root can also be used for push-falling present in non-symptomatic trees disease. Although it was not entirely successful, it did trees. After push-falling, the trees outside the obvious infection restrict expansion of the are shaken to remove soil from the center and may become new disease along most of the root wad. Roots still need to be expanding centers. treated edge. raked from the stump site after We have little experience with push-falling. As many of the large physical removal of inoculum in roots as possible are removed from inland forests (see sidebar). These the soil. Once deposited above approaches probably have limited ground the roots become too dry to application in Idaho and Montana support the pathogen. where at least two other aggressive root pathogens are also likely to be

Either method is expensive and present both within and outside of In most cases, infections are would likely only be used on high- obvious infection centers. dispersed throughout the value sites where Douglas-fir or forest area, limiting the use of this control method. grand fir were the preferred Chemical control species. In the interest of operator Most of the early research safety, slopes should be less that efforts were aimed at fumigating 30 percent (Thies and Sturrock around or in stumps to kill 1995). inoculum. A recent study has also shown efficacy in killing Sanitizing the infested area infections in living trees. Destumping infection centers has reduced laminated root rot

Page 16 Back to menu Laminated Root Rot 11.4

Stump treatments to reduce this success in reducing inoculum, Non-target effects inoculum just 16 years after replanting with of chloropicrin Emphasis for chemical control Douglas-fir, there was no stump treatment has been eradication or reduction reduction in the amount of of inoculum in dead tissues of laminated root rot near treated No significant release stumps. We know that P. stumps compared to non-treated of chloropicrin from stumps. treated stumps into sulphurascens infections are often surrounding soil at abundant in apparently healthy Perhaps the most important one year following portions of a forest, not associated discovery here is the realization treatment (Ingham with recognizable disease centers that very little inoculum is needed and Thies 1995) and at 5 years following (Thies and Nelson 1997). to sustain a disease center from treatment However, nearly all mortality one generation of host trees to the (Massicotte and occurs within active disease next. others 1998). centers. Therefore it is tempting to Little or no effect on try eliminating the fungus from Curatives for live trees vegetation three disease centers thereby returning More recently, Harrington and years following fumigation (Luoma the site to Douglas-fir Thies (2007) have reported and Thies 1997) productivity. De-stumping is often success of MITC, chloropicrin, and Vorlex as curatives for No affect on not practical because of steep mycorrhizae on terrain, large stumps, soil infected roots in live trees. Nearly Douglas-fir seedlings disturbance and the difficulty of all fumigant treatments reduced 4 to 5 years after removing the decayed roots that root infection and, in some cases stump treatment (Massicotte and break away from stumps. eliminated infection. Live Douglas others 1998). Chemical fumigation of -fir tolerated most of the tested fumigant treatments, although Rare and minor stumps to kill the pathogen has effects on soil fungi, been somewhat more successful in there was some cambium damage. bacteria and amoeba eliminating most of the inoculum The authors suggested that altering populations near (Thies and Nelson 1987, Fraser the time of treatment to the treated stumps in the dormant season may reduce tissue first year following and others 1995). Holes are drilled treatment ((Ingham into the tops of stumps, the damage. These results are and Thies 1995). fumigant is poured in, and the encouraging because they suggest No effect on soil holes are plugged. The authors a potential to treat high-value trees arthropods and reported reduction of infected root growing in residential or nematodes the first tissue to just 22% (by weight) of administrative locations. Further year after treatment research is needed to refine the (Ingham and Thies what they estimated to have been 1995). infected before treatment. Despite application procedures.

Other Reading Angwin, P. A. 1989. Genetics of sexuality and population genetics of Phellinus weirii. Ph.D. Disserta- tion, Oregon State University, Corvallis OR, 175 pp. Angwin, P. A. and Hansen, E. M. 1988. Population structure of Phellinus weirii. In: Proceedings of the seventh international Conference on Root and Butt Rots. (ed. D. Morrison) pp. 371-380. Pacific Forestry Centre, Victoria, B.C. Angwin, P. A. and E. M. Hansen. 1993. Pairing tests to determine mating compatibility in Phellinus weirii. Mycol. Res. 97(12) 1469– 1475. Bae, H.. E. M. Hansen, S. H. Strauss. 1994. Restriction fragment length polymorphisms demonstrate single origin of infection centers in Phellinus weirii. Can. J. Bot. 72:440-447. 11.4 Back to menu Laminated Root Rot Page 17

Banik, M. T., J. A. Paul, H. H. Burdsall, Jr., and M. E. Cook. 1993. Serological differentiation of two forms of Phellinus weirii. Mycologia 84(4): 605-611. Bloomberg, W. J. 1990. Effect of stand conditions on advance of Phellinus weirii in Douglas-fir planta- tions. Phytopathology 80: 553-559. Bloomberg, W. J. and G. W. Wallis 1979. Comparison of indicator variables for estimating growth re- duction associated with Phellinus weirii root rot in Douglas-fir plantations. Can. J. For. Res. 9: 76- 81. Bloomberg, W. J. and G. Reynolds. 1985. Growth loss and mortality in laminated root rot infection centers in second growth Douglas-fir on Vancouver Island. Forest Science 31: 497-508. Buckland, D. C., A. C. Molnar and G. W. Wallis. 1954. Yellow laminated root-rot of Douglas-fir. Can. J. Bot. 32: 69-81. Byler, J. W. ; M. A. Marsden; S. K. Hagle. 1992. The probability of root disease on the Lolo national Forest, Montana. Can. J. For. Res. 20: 987-994. Dickman, A., and S. Cook. 1988. Fire and fungus in a mountain hemlock forest. Can. J. Bot. 67: 2005- 2016. Filip, G.M. and C. L. Schmitt. 1979. Susceptibility of native conifers to laminated root rot east of the Cascade Range in Oregon and Washington. For. Sci. 25; 261-265. Fraser, R. G., J. D. Beale and R. J. Nevill. 1995. Reduction of Phellinus weirii inoculum in Douglas-fir stumps by the fumigant Telone 11-B. Hadfield, J.S. 1985. Laminated root rot: A guide to reducing and prevent losses in Oregon and Wash- ington forests. USDA For. Serv., For. Pest Manage., PNW, 13 p. Hagle, S. K. 1992. Rating for root disease severity. In: Frankel, S., comp. Proceedings, 40th annual western international forest disease work conference; 1992 July 13 - 17; Durango CO, San Fran- cisco, CA: USDA Forest Service, Pacific Southwest Region: 80-86. Hagle, S. K. 2006. Rating for root disease severity. On the web at: http://www.fs.fed.us/r1-r4/spf/fhp/ root disease risk.htm Hagle, S., J. Byler, S. Jeheber-Matthews, R. Barth, J. Stock, B. Hansen, and C. Hubbard. 1994. Root disease in the Coeur d’Alene River Basin: An assessement. In: Proceedings of Interior Cedar- Hemlock-White pine forests: Ecology and Management, March 2-4, 1993, Spokane, WA; Dep. Nat. Res. Sci., Wash. St. Univ., Pullman 335-344. Hagle, S. K., Kenneth E. Gibson, Scott Tunnock. 2003. Field guide to diseases and insect pests of northern and central Rocky Mountain conifers. U.S.D.A. Forest Service, Northern and Intermoun- tain Regions, Rept. No. R1-03-08. 197 pp. Hansen, E. M. 1976. Twenty year survival of Phellinus (Poria) weirii in Douglas-fir stumps. Can. J. For. Res. 6: 123-128. Hansen, E. M. 1979a. Survival of Phellinus weirii in Douglas-fir stumps after logging. Can. J. For. Res. 9: 484-488. Hansen, E. M. and E. M. Goheen. 2000. Phellinus weirii and other native root pathogens as determi- nants of forest structure and process in western North America. Annu. Rev. Phytophathol. 38: 515- 539. Harrington, C. A. and W. G. Thies. 2007. Laminated root rot and fumigant injection affect survival and growth of Douglas-fir. West. J. Appl. For. 22(3): 220-227.

Page 18 Back to menu Laminated Root Rot 11.4

Hoffman, J. 2004. Dwarf Mistletoe Management; Insect and Disease Management in the Northern and Central Rocky Mountains, Chapter 12.0. USDA Forest Service, Forest Health Protection. 15 p. http://www.fs.fed.us/r1-r4/spf/fhp/mgt_guide/index.htm Holah, J. C., M. V. Wilson, and E. M. Hansen. 1993. Effects of a native forest pathogen, Phellinus weirii, on Douglas-fir forest composition in western Oregon. Can. J. Forest. Res. 23: 2473-2480. Holah, J. C., M. V. Wilson and E. M. Hansen. 1997. Impacts of a native root-rotting pathogen on suc- cessional development of old-growth Douglas-fir forests. Oecologia 111: 429-433. Ingham, E. R. and W. G. Thies. 1995. Responses of soil foodweb organisms in the first year following clearcutting and application of chloropicrin to control laminated root rot. Appl. Soil Ecol. 3: 35-37. Ingersoll, C. A., M. V. Wilson, and W. G. Thies. 1996. Effects of Phellinus weirii gaps on early suc- cessional vegetation following timber harvest. Can. J. For. Res. 26: 322-326. Larsen M. J. and F. F. Lombard. 1989. and nomenclature of Phellinus weirii in North America Pp. 573-578. In: Proceedings of the 7th Intrnational conference on Root and Butt Rots: 1988 August 9-16; Vernon and Victoria, BC, Canada. International Union of Forestry Research Or- ganizations (IUFRO) Working Party S2.06.01. Ed., D. J. Morrison, Forestry Canada, Pacific For- estry Centre, BC, Canada. Larsen, M. J., F. F. Lombard and J. W. Clark. 1994. Phellinus sulphurascens and the closely related P. weirii in North America. Mycologia 86: 121-130. Lim, Y. W., R. Sturrock, I. Leal, K. Pellow, T. Yamaguchi, C. Breuil. 2008. Distinguishing homokary- ons and heterokaryons in Phellinus sulphurascens using pairing tests and ITS polymorphisms. An- tonie van Leeuwenhoek 93: 99-110. Luoma, D. L. and W. G. Thies. 1997. Stumps fumigated with chloropicrin: effects on surrounding plants. Can. J. For. Res. 27: 1737-1745. Massicotte, H. B., L. E. Tackaberry, E. R. Ingham and W. G. Thies. 1998. Ectomycorrhizae establish- ment on Douglas-fir seedlings following chloroicrin treatment to control laminated-root rot disease: Assessment 4 and 5 years after outplanting. Appl. Soil Ecol. 10: 117-125. Miller, R. E., T. B. Harrington, W. G. Thies and J. Madsen. 2006 Laminated root rot in a western Washington plantation: 8-year mortality and growth of Douglas-fir as related to infected stumps, tree density, and fertilization. Res. Pap. PNW-RP-569. Portland, OR: U.S. Dept. of Agric. For. Serv. Pacific Northwest Research Station. 37 p. Moore, J. A., P.G. Mika, T. M. Shaw, M. I. Garrison-Johnson. 2004. Foliar nutrient characteristics of four conifer species in the interior northwest United States. Western Journal of Applied Forestry 19(1): 13-24. Morrison, D. J. G. W. Wallis and L. C. Weir. 1988. control of Armillaria and Phellinus root diseases: 20-year results from the Skimikin stump removal experiment. Canadian Forestry Service, Pacific Forestry Centre. Report BC-X-302. 16 p. Nelson, E. E. 1964. Some probable relationships of soil fungi and zone lines to survival of Poria weirii in buried wood blocks. Phytopathology 54: 120-121. Nelson, E. E. and W. G. Thies. 1985. Colonization of Phellinus weirii-infested stumps by Trichoderma viride. 1.: Effect of isolate and inoculum base. European Journal of Forest Pathology. 15: 425-431. Nelson, E. E and W. G. Thies. 1986. Colonization of Phellinus weirii-infested stumps by Trichoderma viride. 2: Effects of season of inoculation and stage of wood decay. European Journal of Forest Pa- thology. 16: 56-60. 11.4 Back to menu Laminated Root Rot Page 19

Nelson, E. E. and R. N. Sturrock. 1993. Susceptibility of western conifers to laminated root rot (Phellinus weirii) in Oregon and British Columbia field tests. West. J. Appl. For. 8(2): 67-70. Nelson, E. E., M. G. McWilliams and W. G. Thies. 1994. Mortality and growth of urea-fertilized Douglas-fir on a Phellinus weirii-infested site in Oregon. Western Journal of Applied Forestry 9(2): 52-56. Sturrock, R. N., Islam, M. A. and A. K. M. Ekramoddoullah. 2007. Host-pathogen interactions in Douglas-fir seedlings infected by Phellinus sulphurascens. Phytophathology 97: 1406-1414. Thies, W. G., E. E. Nelson and D. Zabowski. 1974. Removal of stumps from a Phellinus weirii infested site and fertilization affect mortality and growth of planted Douglas-fir. Can. J. For. Res. 24: 234 - 239. Thies, W. G. and E. E. Nelson. 1987. Reduction of Phellinus weirii inoculum in Douglas-fir stumps by the fumigants chloropicrin, Vorlex, or methylisothiocyanate. Forest Science 33: 316-329. Thies, W. G. and R. N. Sturrock. 1995. Laminated root rot in western North America. Gen. Tech. Rep. PNW-GTR-349. Portland, OR: U.S. Dept. of Agric., For. Serv., Pacific Northwest Res. Sta. 32 p. Thies, W. G. and E. E. Nelson. 1997. Laminated root rot: New consideration for surveys. West. J. Appl. For. 12(2): 49-51. Thies, W. G. and D. J. Westlind. 2005. Stump removal and fertilization of five Phellinus weirii-infested stands in Washington and Oregon affect mortality and growth of planted Douglas-fir 25 years after treatment. Forest Ecology and Management 219: 242-258. Thies, W. G. and D. J. Westlind. 2006. Application of chloropicrin to Douglas-fir stumps to control laminated root rot does not affect infection or growth of regeneration 16 growing seasons after treatment. For. Ecol. and Management 235: 212-218. Tkacz, B. M. and E. M. Hansen. 1982. Damage by laminated root rot in two succeeding stands of Douglas-fir J. For. 80: 788-791. Wallis, G. W. and W. J. Bloomberg. 1981. Estimating the total extent of Phellinus weirii root rot cen- ters using above-and below-ground disease indicators. Can. J. For. Res. 11: 827-830.

Publication Citation

Hagle, S. K. 2009. Laminated root rot ecology and management. Chapter 11.2 Forest insect and disease management guide for the northern and central Rocky Mountains. USDA Forest Service, Northern Region, State and Private Forestry. 20 pp.

Available from USDA Forest Service, Idaho Department of Lands, and Montana Department of Natural Resources.

Online at: http://www.fs.fed.us/r1-r4/spf/fhp/mgt_guide/index.htm

Page 20 Back to menu Laminated Root Rot 11.4

Forest Health Protection and State Forestry Organizations

Assistance on State and Assistance on Private Lands Federal Lands

Montana: (406) 542-4300 US Forest Service Region One Idaho: (208) 769-1525 Missoula: (406) 329-3605 Utah: (801) 538-5530 Coeur d’Alene: (208) 765-7342

Nevada: (775) 684-2500 US Forest Service Wyoming: (307) 777-5659 Region Four Ogden; (801) 476-9720 Boise: (208) 373-4227

Disclaimers | Privacy Policy