United States Forest Northern 200 East Broadway 

Department of Service Region P.O. Box 7669 

Agriculture Missoula, MT 59807 

Numbered Report 07-05 July 2007 

ROOT COLONIZATION OF CONTAINER WESTERN WHITE PINE 

SEEDLINGS BY FUSARIUM AND CYLINDROCARPON SPECIES 

R.L. James, Plant Pathologist 

USDA Forest Service, Forest Health Protection 

Coeur d’Alene, Idaho
 

ABSTRACT 

Healthy-appearing container western white pine seedlings were sampled at an Idaho forest nursery eight 

times during the crop production cycle at monthly intervals for root colonization by potentiallypathogenic Fusarium and Cylindrocarpon spp. in an attempt to better understand epidemiological changes 

that might occur by these fungi over time. Fusarium spp., especially F. proliferatum, were present at 

relatively high levels throughout the seedling production cycle. However, Cylindrocarpon (mostly C. 

destructans) was not detected until seedlings were 4-5 months old. Levels of Cylindrocarpon root 

colonization remained much less than that of Fusarium spp. Although high levels of Fusarium 

contaminated seeds prior to sowing, those species most likely to cause disease were only detected at low 

levels; Cylindrocarpon spp. also contaminated few seeds. During the evaluation period, very low root 

disease occurred; few culled seedlings and good root plug condition was the standard on the sampled 

seedling crop. 

INTRODUCTION 

Root diseases of container-grown western white 

pine (Pinus monticola Dougl.) seedlings have 

periodically caused extensive damage to crops, 

resulting in reduced number of satisfactory 

seedlings produced and lowered seedling quality 

(James 1985b, 1987a, 1990a, 1991c). The major 

fungal pathogens routinely associated with such 

diseases include species of Fusarium and 

Cylindrocarpon (James 1985a, 1988a, 1990b). In 

some cases, distinctive above-ground disease 

symptoms associated with extensive root 

colonization by these organisms are evident 

(James 1987a, 1989a, 1990a, 1991d, 2003b). 

However, all too often no discernable disease 
symptoms are present even though extensive root 

decay may have occurred (James 1988a, 1991a, 

1991b, 2004a). In such cases, diseased seedlings 

only become evident after they are removed from 

containers; they often have high levels of root 

decay and are culled. Most previous 

investigations involved determining associated 

fungal organisms at the end of the crop growing 

cycle when diseased seedlings were detected 

following lifting. However, information on the 

temporal changes in fungal root colonization 

during a typical crop production cycle by 

different potentially-pathogenic organisms was 

lacking. An evaluation was conducted during 

2006 to provide such information. 

MATERIALS AND METHODS 

A large container nursery in Idaho was selected 

for this evaluation. This nursery has traditionally 

produced large number of western white pine 

seedlings for reforestation. The goal of this 

evaluation was to determine changes in root 

colonization by Fusarium and Cylindrocarpon 

spp. during the crop production cycle. All seed 

used to produce seedlings was obtained from the 

same seed orchard which produces improved 

seed developed for resistance to white pine 

blister rust (Cronartium ribicola). A sample of 

100 seeds from bulk storage was analyzed for 

surface contamination by Fusarium and 

Cylindrocarpon spp. Seeds were aseptically 

placed on a selective agar medium for Fusarium 

and closely-related fungal species (Komada 

1975). Agar plates were incubated under diurnal 

cycles of cool, fluorescent light at about 24o

C for 

7-10 days. Selected emerging fungi were 

transferred to carnation leaf agar (Fisher et al. 

1982) and potato dextrose agar for identification 

using the taxonomy of Nelson et al. 1989 and 

Booth 1966. Percentages of seeds colonized by 

particular fungal species were determined. 

Seedlings were grown in three production areas: 

two greenhouses (designated 5 and 7) and one 

shade house area (designated “bay”). Seedlings 

grown in two container sizes (5s – 120 

cells/block and 8s – 91 cells/block) were 

sampled eight times at approximately monthly 

intervals beginning in April. During each 

sampling period, five seedlings were randomly 

selected for laboratory analysis of fungal root 

colonization from each of the production areas 

and container sizes; this resulted in four separate 

samples (house 7 – 5s; house 7 – 8s; house 5 – 

8s; bay – 8s) during each monthly sampling 

period. Selected seedlings were carefully 

extracted from containers and placed into 

individual plastic bags. They were transported to 

the laboratory and analyzed immediately for 

fungal root colonization. 

Seedling roots were washed thoroughly to 

removed adhering peat growing media. Ten root 

pieces, each ap-proximately 5 mm, were 

randomly dissected from each seedling, surface 

sterilized in 0.5% aqueous sodium hypochlorite 

(10% bleach solution), rinsed in sterile water, 

placed on the selective agar medium and 

incubated as described above. Associated 

Fusarium and Cylindrocarpon spp. were 

identified and percentages of sampled root pieces 

colonized by particular fungal species were 

determined. 

At the end of the production cycle when 

seedlings were lifted from containers, a selected 

number of seedlings were collected for 

examination of their root systems (plugs) to 

determine extent of noticeable root decay. 

Seedling root plugs were placed into one of three 

categories based on the extent of root decay. 

Poor root systems exhibited extensive root decay 

with few roots remaining at the bottom of the 

plug; moderate root systems had an intermediate 

level of root decay that may have compromised 

the root plug integrity, i.e., some of the growing 

media became dislodged when seedling were 

extracted from containers. Good root systems 

exhibited very little or no noticeable root decay 

and the root plug integrity was maintained upon 

seedling extraction. In addition, the percentage 

2
 
of seedlings culled due to poor root development 

(indicating decay and associated effects on root 

plug integrity) was determined from seedlings 

extracted from five randomly-selected containers 

in each of the four sampled production areas. 

RESULTS 

Nearly all sampled western white pine seeds 

were contaminated with at least one species of 

Fusarium (table 1). Four Fusarium species were 

detected on bulk seed samples. These included, 

in descending order of prevalence, F. 

acuminatum Ell. & Ev., F. culmorum (W.G. 

Smith) Sacc., F. proliferatum (Matsushima) 

Nirenberg and F. equiseti (Corda) Sacc. 

Extent of root colonization by Fusarium was 

apparently higher within house 7 than the two 

other production areas (table 2). In some cases, 

high levels of Fusarium colonization was 

detected early in the seedling production cycle, 

whereas in others, levels of colonization 

generally increased over time. The highest 

overall Fusarium root colonization was detected 

during the October sample, approximately 7 

months after sowing (table 2). Eleven different 

Fusarium species were detected on seedling 

roots (table 3). Seven of these species were 

found only at extremely low levels; three others 

(F. acuminatum, F. culmorum, and F. 

avenaceum (Fr.) Sacc.) were isolated more 

frequently. However, by far the most prevalent 

Fusarium species isolated from seedling roots 

was F. proliferatum. Throughout the sampling 

period, Fusarium was isolated from nearly twothirds of the sampled root pieces (table 3). 

The other assayed group of root-colonizing 

organisms was Cylindrocarpon. These fungi 

were detected at much lower levels than 

Fusarium spp. (table 4). Cylindrocarpon spp. 

were not detected until seedlings were four 

months old in one production area (house 7) or 

five months old in the other two areas. By the 

end of the production cycle, Cylindrocarpon spp. 

were only detected on a little more than a third of 

the sampled roots (table 4). By far, the most 

common Cylindrocarpon species isolated from 

roots was C. destructans (Zins.) Scholten. 

Percent of culled seedlings at lifting was 

generally quite low (table 5). Seedlings were 

culled for various reasons, but primarily because 

they failed to reach size and quality 

specifications. More than two-thirds of the 

examined root systems at the time of lifting were 

considered to be in good condition, based 

primarily on the extent of root decay that was 

evident (table 5). In some cases (house 7 – 8s; 

house 5 – 8s), none of the examined seedlings 

had root systems considered to be in poor 

condition. 

DISCUSSION 

Excessive root decay of container western white 

pine seedlings, resulting in high cull levels, and 

poor outplanting performance, has normally be 

ascribed to high levels of root colonization by 

Cylindrocarpon, spp., especially C. destructans 

(James 1988a, 2003a, 2004a; James et al. 1994). 

These fungi are routinely isolated from seedling 

roots exhibiting decay symptoms, especially loss 

of cortical cell tissues (James 1988b, 1995, 2000; 

James et al. 1994). High seedling losses in 

nurseries have often been associated with 

excessive moisture being maintained for 

prolonged periods within root plugs. Fortunately, 

Cylindrocarpon levels on colonized roots tend to 

decrease over time following outplanting onto 

forest sites, usually being replaced with other, 

less innocuous, fungi (Dumroese et al. 2000). 

Although Cylindrocarpon has been associated 

with important conifer seedling diseases in 

nurseries (Beyer-Ericson et al. 1991; Bloomberg 

and Sutherland 1971; Evans 1967; James 1988a, 

2004b; Unestam and Beyer-Ericson 1990), the 

aggressiveness of this species has been 

questioned, especially when seedlings are grown 

under non-stressful conditions (Dahm and 

3
 
Strzelcayk 1987a, 1987b). In fact, many white 

pine seedlings with extensive root decay 

attributed to Cylindrocarpon do not exhibit any 

disease symptoms during the production cycle; 

they are only detected once seedlings have been 

removed from their containers (James 1988a; 

James et al. 1994). 

In this evaluation, Cylindrocarpon spp., 

primarily C. destructans, were isolated at fairly 

low levels, especially when compared with root 

colonization by Fusarium spp. Cylindrocarpon 

was not detected early in the crop production 

cycle and relatively high colonization frequency 

was found only in one production area (house 7) 

by the end of the growth cycle. 

On the other hand, Fusarium root colonization 

was generally much higher during all sampling 

periods. Although a wide range of species were 

isolated from seedling roots, F. proliferatum was 

by far the most common. This species has often 

been previously implicated in container seedling 

root diseases (James and Dumroese 2006; James 

et al. 1995); some isolates have been shown to be 

highly virulent on young conifer seedlings, at 

least under controlled greenhouse growing 

conditions or within in vitro laboratory 

experiments (James et al. 1997). Although 

previous evaluations indicated that F. 

proliferatum increases in intensity of root 

colonization as the seedling crop ages (James 

1991c, 1991d; James and Gilligan 1990), in the 

current evaluation relatively high levels of root 

colonization by this fungus were found on very 

young seedlings. 

Fusarium and Cylindrocarpon inoculum has 

often been detected on sown seeds (James 

1987b, 1987c, 1988a, 1989b), containers used to 

grown previous seedling crops (Dumroese et al. 

2002), and on various types of organic matter 

within and adjacent to greenhouse environments 

(James 2003a; James and Dumroese 2006). In 

the current evaluation, Cylindrocarpon was 

detected on only 2% of the sampled seeds. 

Although Fusarium spp. were detected at high 

levels on seeds, F. proliferatum, the species with 

the highest disease potential (James et al. 1995, 

1997) was detected on only 5% of the seeds. 

Therefore, it appears that contaminated seeds 

were not an important source of either Fusarium 

or Cylindrocarpon inoculum. 

Styrofoam containers used to produce seedlings 

were not sampled in this evaluation. However, 

growers use standard hot water sterilization 

treatments to clean containers that have been 

used to produce previous seedling crops. These 

treatments have usually been quite effective in 

eliminating inoculum of potentially-pathogenic 

fungi (Dumroese et al. 2002). Therefore, it is 

unlikely that high levels of either Cylindrocarpon or Fusarium were introduced into the 

white pine seedling crop via contaminated 

containers. 

Organic debris within or surrounding seedling 

production greenhouses or shade houses may 

have contributed Cylindrocarpon and Fusarium 

inoculum. Likewise, weeds can also harbor these 

fungi. However, neither organic debris or weeds 

were assayed for potential pathogens, so the 

extent of these two sources as a source of 

Cylindrocarpon or Fusarium inoculum is 

unknown. 

Root diseases caused by Cylindrocarpon and/or 

Fusarium spp. will continue to be of concern to 

container seedling growers. Both groups of fungi 

can cause devastating losses when virulent 

fungal isolates and conducive environmental 

conditions are present. Although losses during 

the current evaluation were very low, continued 

low disease levels cannot be guaranteed for the 

future. Careful vigilance of growers will be 

necessary to make sure seedling crops are not 

stressed to the point where these potential 

pathogens can cause important losses. 

4
 
LITERATURE CITED 

Beyer-Ericson L, Dahm E, Unestam T. 1991. An 

overview of root dieback and its causes in 

Swedish nurseries. European Journal of Forest 

Pathology 21:439-443. 

Bloomberg WJ, Sutherland JR. 1971. Phenology 

and fungus-nematode relations of corky root 

disease of Douglas-fir. Annals of Applied 

Biology 69:265-276. 

Booth C. 1966. The genus Cylindrocarpon. The 

Commonwealth Mycological Institute. Kew, 

Surrey, England. Mycological Papers No.104. 

56p. 

Dahm H, Strzelczyk E. 1987a. Cellulolytic and 

pectolytic activity of Cylindrocarpon destructans isolates pathogenic and nonpathogenic to fir (Abies alba) and pine (Pinus 

sylvestris). Journal of Phytopathology 118:76-

83. 

Dahm H, Strzelczyk E. 1987b. Effect of pH, 

temperature and light on the pathogenicity of 

Cylindrocarpon destructans to pine seedlings 

in associative cultures with bacteria and 

actinomycetes. European Journal of Forest 

Pathology 17:141-148. 

Dumroese RK, James RL, Wenny DL. 2000. An 

assessment of Cylindrocarpon on container 

western white pine seedlings after outplanting. 

Western Journal of Applied Forestry 15(1):5-7. 

Dumroese RK, James, RL, Wenny DL. 2002. 

Hot water and copper coatings in reused 

containers decrease inoculum of Fusarium and 

Cylindrocarpon and increase Douglas fir 

seedling growth. HortScience 37:943-947. 

Evans G. 1967. The production of a phytotoxin, 

nectrolide, by some root-surface isolates of 

Cylindrocarpon radicicola. Plant and Soil 

26:253-260. 

Fisher NL, Burgess LW, Toussoun TA, Nelson 

PE. 1982. Carnation leaves as a substrate and 

for preserving cultures of Fusarium species. 

Phytopathology 72:151-153. 

James RL. 1985a. Containerized western white 

pine seedling mortality at the Bonners Ferry 

Ranger District, Idaho Panhandle National 

Forests. USDA Forest Service, Northern 

Region, Forest Pest Management. Report 85-

18. 7p. 

James RL. 1985b. Root diseases of transplanted 

western white pine seedlings at the USDA 

Forest Service Nursery, Coeur d'Alene, Idaho. 

USDA Forest Service, Northern Region, Forest 

Pest Management. Nursery Disease Notes #21. 

4p. 

James RL. 1987a. Containerized western white 

pine seedling root disease - USDA Forest 

Service Nursery, Coeur d'Alene, Idaho. USDA 

Forest Service, Northern Region, Forest Pest 

Management. Nursery Disease Notes #66. 4p. 

James RL. 1987b. Fungi on bleach-treated 

western white pine seed, Raintree Nursery, 

Libby, Montana. USDA Forest Service, 

Northern Region, Forest Pest Management. 

Nursery Disease Notes #48. 1p. 

James RL. 1987c. Occurrence of fungi on 

western white pine seed - Plum Creek Nursery, 

Pablo, Montana. USDA Forest Service, 

Northern Region, Forest Pest Management. 

Nursery Disease Notes #45. 3p. 

James RL. 1988a. Diseases of conifer seedlings 

associated with Cylindrocarpon species: a 

review. USDA Forest Service, Northern 

Region, Forest Pest Management. Nursery 

Disease Notes #76. 14p. 

James RL. 1988b. Field mortality of western 

white pine transplants - Kootenai National 

5
 
Forest. USDA Forest Service, Northern 

Region, Forest Pest Management. Nursery 

Disease Notes #71. 3p. 

James RL. 1989a. Chlorosis of container-grown 

western white pine seedlings - Fisher River 

Ranger District, Kootenai National Forest, 

Montana. USDA Forest Service, Northern 

Region, Forest Pest Mangement. Nursery 

Disease Notes #87. 4p. 

James RL. 1989b. Occurrence of fungi on 

western white pine seed - Idaho Department of 

Lands. USDA Forest Service, Northern 

Region, Forest Pest Management. Nursery 

Disease Notes #84. 6p. 

James RL. 1990a. Needle tip dieback of 

container-grown western white seedlings -

Champion Timberlands Nursery, Plains, 

Montana. USDA Forest Service, Northern 

Region, Forest Pest Management. Nursery 

Disease Notes #103. 4p. 

James RL. 1990b. Needle-tip necrosis of 

container-grown western white pine seedlings -

University of Idaho Research Nursery. USDA 

Forest Service, Northern Region, Forest Pest 

Management. Nursery Disease Notes #106. 4p. 

James RL. 1991a. Cylindrocarpon root disease of 

container-grown whitebark pine seedlings -

USDA Forest Service Nursery, Coeur d'Alene, 

Idaho. USDA Forest Service, Northern Region, 

Forest Pest Management. Report 91-8. 10p. 

James RL. 1991b. Fungal colonization of roots 

from western white pine transplant seedlings 

outplanted on the Wallace Ranger District, 

Idaho Panhandle National Forests, Idaho. 

USDA Forest Service, Northern Region, Forest 

Pest Management. Nursery Disease Notes 

#120. 10p. 

James RL. 1991c. Root decay of containergrown lodgepole pine and western white pine 

seedlings - USDA Forest Service Nursery, 

Coeur d'Alene, Idaho. USDA Forest Service, 

Northern Region, Forest Pest Management. 

Nursery Disease Notes #116. 4p. 

James RL. 1991d. Wilting of container-grown 

western white pine seedlings - USDA Forest 

Service Nursery, Coeur d'Alene, Idaho. USDA 

Forest Service, Northern Region, Forest Pest 

Management. Nursery Disease Notes #123. 5p. 

James RL. 1995. Root diseases of western white 

pine transplants - USDA Forest Service 

Nursery, Coeur d'Alene, Idaho. USDA Forest 

Service, Northern Region, Insect and Disease 

Manage-ment. Report 95-8. 10p. 

James RL. 2000. Diseases associated with 

whitebark pine seedling production – USDA 

Forest Service Nursery, Coeur d’Alene, Idaho. 

USDA Forest Service, Northern Region, Forest 

Health Protection. Report 00-8. 11p. 

James RL. 2003a. Diseases in forest nurseries: 

implications for forest managers. Western 

Forester 48(5):8-9. 

James RL. 2003b. Fungal associates of corky 

root syndrome of bare root 2-0 western white 

pine seedlings - USDA Forest Service Nursery, 

Coeur d’Alene, Idaho. USDA Forest Service, 

Northern Region, Forest Health Protection. 

Nursery Disease Notes No. 150. 7p. 

James RL. 2004a. Cylindrocarpon destructans 

associated with root disease of containergrown western white pine tree improvement 

stock - USDA Forest Service Nursery, Coeur 

d’Alene, Idaho. USDA Forest Service, 

Northern Region, Forest Health Protection. 

Nursery Disease Notes No. 155. 9p. 

James RL. 2004b. Pathogen infection and 

colonization of container-grown whitebark 

pine seedlings - USDA Forest Service Nursery, 

Coeur d’Alene, Idaho. USDA Forest Service, 

6
 
 

Northern Region, Forest Health Protection. 

Nursery Disease Notes No. 154. 10p. 

James RL, Dumroese RK. 2006. Investigations 

of Fusarium diseases within inland Pacific 

Northwest Forest Nurseries. In: Guyon, J.C. 

[compiler]. Proceedings of the 53rd Western 

International Forest Disease Work Conference: 

2005 August 26-29; Jackson, WY; USDA 

Forest Service Intermountain Region. pp. 3-11. 

James RL., Dumroese RK, Wenny DL. 1994. 

Observations on the association of Cylindrocarpon spp. with diseases of container grown 

conifer seedlings in the inland Pacific 

Northwest of the United States. In: Perrin, R. 

and J. R. Sutherland (eds.). Diseases and 

Insects in Forest Nurseries. Dijon, France, 

October 3-10, 1993. Institut National De La 

Recherche Agronominque. Les Colloques No. 

68. pp. 237-246. 

James RL, Dumroese RK, Wenny DL. 1995. 

Fusarium proliferatum is a common, 

aggressive pathogen of container-grown 

conifer seedlings. Phytopathology 85(10): 

1129. 

James RL., Dumroese RK, Wenny DL. 1997. 

Pathogenicity of Fusarium proliferatum in 

container-grown Douglas-fir seedlings. In: 

James, R. L. (editor). Proceedings of the third 

meeting of IUFRO Working Party S7.03-04 

(Diseases and Insects in Forest Nurseries). 

USDA Forest Service, Northern Region, Forest 

Health Protection. Report 97-4. pp. 26-33. 

James RL, Gilligan CJ. 1990. Root decay of 

container-grown western white pine seedlings -

Plum Creek Nursery, Pablo, Montana. USDA 

Forest Service, Northern Region, Forest Pest 

Management. Report 90-10. 18p. 

Komada H. 1975. Development of a selective 

medium for quantitative isolation of Fusarium 

oxysporum from natural soil. Review Plant 

Protection Research (Japan) 8:114-125. 

Nelson PE, Toussoun TA, Marasas WFO. 1983. 

Fusarium species: an illustrated manual for 

identification. The Pen-nsylvania State 

University Press, University Park. 193p. 

Unestam T, Beyer-Ericson L. 1990. Diseases of 

containerized conifer seedlings in Swedish 

Nurseries. In: Sutherland, J. R. and S. G. 

Glover (eds.). Proceedings of the first meeting 

of IUFRO Working Party S2.07-09 (Diseases 

and Insects in Forest Nurseries). Forestry 

Canada. Pacific and Yukon Region. 

Information Report BC-X-331. pp. 105-108. 

Table 1. Contamination of western white pine seeds with Fusarium and other selected fungi. 

Fungal Species Percent Contamination1 

Fusarium acuminatum 73 

Fusarium culmorum 20 

Fusarium proliferatum 5 

Fusarium equiseti 3 

All Fusarium 98 

Cylindrocarpon destructans 2 

Botrytis cinerea 1 

1

Sample based on 100 randomly-selected seeds from bulk storage prior to sowing. 

7 
Table 2. Colonization of container western white pine seedling roots with Fusarium spp. 

Sample Date Production Area1 All Samples 

A – House 

7; 5s 

B – House 7; 

8s 

C – House 5; 

8s 

D – Bay; 8s 

4/06 97 52 11 25 48 

5/06 66 46 22 24 37 

6/06 96 76 18 72 67 

7/06 62 88 68 76 73.5 

8/06 74 74 36 66 67.5 

9/06 94 96 50 46 71.5 

10/06 80 100 66 90 84 

12/06 59 75 62 62 63 

Averages 72 79 47 60 64 

1

Each seedling production area designated with greenhouse number (or open shade house area – Bay) and the 

container sizes used in that area (5s = 120 cells/block; 8s = 91 cells/block). 

Table 3. Fusarium species colonizing roots of container western white pine seedlings. 

Fusarium Species Percent of Samples1 Percent Root Colonization2 

Fusarium proliferatum 100 48.5 

Fusarium acuminatum 87.5 6.0 

Fusarium culmorum 75 3.9 

Fusarium avenaceum 50 3.2 

Fusarium oxysporum 50 1.2 

Fusarium sporotrichioides 25 0.9 

Fusarium scirpi 25 0.7 

Fusarium sambucinum 12.5 0.4 

Fusarium equiseti 50 0.4 

Fusarium tricinctum 12.5 0.3 

Fusarium heterosporum 12.5 0.1 

All Species 100 64.5 

1

Percent of the 8 sampling times throughout the growing season that particular Fusarium species were detected. 

2

Overall percent of sampled root pieces colonized by particular Fusarium species – total number of root pieces 

sampled = 1,953. 

8 
Table 4. Colonization of container western white pine seedling roots with Cylindrocarpon spp. 

Sample Date Production Area1 All Samples 

A – House 

7; 5s 

B – House 7; 

8s 

C – House 5; 

8s 

D – Bay; 8s 

4/06 0 0 0 0 0 

5/06 0 0 0 0 0 

6/06 0 0 0 0 0 

7/06 40 4 0 0 13.5 

8/06 70 8 42 22 35.5 

9/06 12 2 44 34 23 

10/06 38 0 20 20 19.5 

12/06 61 31 26 17 34.9 

Averages 37.5 10 19 13.5 20.52 

1

Each seedling production area designated with greenhouse number (or open shade house area – Bay) and the 

container sizes used in that area (5s = 120 cells/block; 8s = 91 cells/block). 

2

Cylindrocarpon isolates comprised 99% C. destructans and 1% C. gracile. 

Table 5. Root plug condition and percent culls of container western white pine seedlings at the time of 

lifting [12/06]. 

Production 

Area 

Root Plug Condition1 Percent 

Seedling Culls2 Poor Moderate Good 

A-House 7 – 5s 26 21 53 2.0 

B-House 7 – 8s 0 8 92 2.0 

C-House 5 – 8s 0 15 85 2.5 

D-Bay – 8s 21 21 58 7.3 

Averages 14.3 17.5 68.2 3.5 

1

Visible condition of plugs at the time of lifting based on extent of noticeable root decay [poor = extensive root 

decay and/or few roots remaining at the bottom of the plug; moderate = moderate root decay with compromised 

root plug integrity; good = little or no root decay evident; root plug integrity maintained]. Number of seedlings 

sampled: A = 19; B = 12; C = 13; D = 19; total = 63. 

2

Five randomly-selected styrofoam blocks with seedlings sampled per production area at the time of lifting. 

Number of cells sampled: A = 600; B = 455; C = 728; D = 455; total = 2238. 

R.L. James is Plant Pathologist, USDA Forest Service, Northern Region, Forest Health Protection. 

Address: USDA Forest Service, 3815 Schreiber Way, Coeur d’Alene, ID 83815; email: rjames@fs.fed.us. 

9