Effects of selective cutting on the epidemiology of armillaria root disease in the southern interior of British Columbia

2001 ◽  
Vol 31 (1) ◽  
pp. 59-70 ◽  
Author(s):  
D J Morrison ◽  
K W Pellow ◽  
A FL Nemec ◽  
D J Norris ◽  
P Semenoff
Keyword(s):  
Host Response ◽  
Root Systems ◽  
Root Disease ◽  
Selective Cutting ◽  
Tree Diameter ◽  
Armillaria Ostoyae ◽  
Primary Roots ◽  
Armillaria Root Disease ◽  
Mature Stands ◽  
Tree Condition

In selectively cut and undisturbed parts of four mature stands, five 0.04-ha plots were established, and trees were measured, mapped, and examined for aboveground symptoms of armillaria root disease. Trees were felled, and stumps and their root systems were removed by an excavator and were measured and examined for Armillaria lesions. Isolates from root lesions, rhizomorphs associated with lesions, and basidiomes collected in or adjacent to plots were of Armillaria ostoyae (Romagn.) Herink. All trees were assigned to one of five tree condition classes based on the location of lesions and host response. The merchantable volume in each class was calculated. In undisturbed plots, incidence of trees with A. ostoyae lesions on roots was about 10% in the dry climatic region compared with about 75% in the moist region and 35% in the wet region. In plots in the selectively cut parts of the stands, 50-100% of stumps were colonized by A. ostoyae. Results of a logistic regression analysis showed that selective cutting was associated with a statistically significant increase in the probability of a tree having A. ostoyae lesions, where the magnitude of the increase depended on tree diameter. The increase in the probability of a tree being diseased was accompanied by an increase in the proportion of primary roots with lesions and the average number of lesions per diseased tree; however, the increases in disease intensity were statistically significant at only two (one dry and one moist) of the four sites. The percentage of merchantable volume threatened or killed by A. ostoyae was usually higher in cutover than undisturbed plots.

scholarly journals Precommercial Thinning in a Ponderosa Pine Stand Affected by Armillaria Root Disease in Central Oregon: 30 Years of Growth and Mortality

1999 ◽  
Vol 14 (3) ◽  
pp. 144-148 ◽  
Author(s):  
Gregory M. Filip ◽  
Stephen A. Fitzgerald ◽  
Lisa M. Ganio
Keyword(s):  
Ponderosa Pine ◽  
Tree Mortality ◽  
Basal Area ◽  
Stand Density ◽  
Root Disease ◽  
Diameter Growth ◽  
Individual Tree ◽  
Precommercial Thinning ◽  
Tree Diameter ◽  
Armillaria Root Disease

Abstract A 30-yr-old stand of ponderosa pine was precommercially thinned in 1966 to determine the effects of thinning on tree growth and mortality caused by Armillaria root disease in central Oregon. After 30 yr, crop tree mortality was significantly (P = 0.02) less in thinned plots than in unthinned plots. Tree diameter growth was not significantly (P = 0.17) increased by thinning. Crop-tree basal area/ac growth was significantly (P = 0.03) greater in thinned plots. Apparently, from a root disease perspective, precommercial thinning of pure ponderosa stands significantly decreases the incidence of crop-tree mortality after 30 yr and significantly increases basal area/ac growth but not individual tree diameter growth. Recommendations for thinning based on stand density index (SDI) are given. West. J. Appl. For. 14(3):144-148.

Precommercial Thinning in a Ponderosa Pine Stand affected by Armillaria Root Disease: 20 Years of Growth and Mortality in Central Oregon

1989 ◽  
Vol 4 (2) ◽  
pp. 58-59 ◽  
Author(s):  
Gregory M. Filip ◽  
Donald J. Goheen ◽  
David W. Johnson ◽  
John H. Thompson
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Tree Mortality ◽  
Root Disease ◽  
Diameter Growth ◽  
Precommercial Thinning ◽  
Tree Diameter ◽  
Armillaria Root Disease ◽  
Forest Managers

Abstract A naturally regenerated stand of ponderosa pine (Pinus ponderosa) was thinned in 1966 to determine the effects of spacing on crop-tree mortality caused by Armillaria root disease in central Oregon. After 20 years, crop-tree mortality in unthinned plots exceeded that in the thinned plots (1.6 vs. 0.8 trees/ac/yr). Crop-tree diameter growth, however, was greater in thinned plots (0.2 vs. 0.1 in./yr). Forest managers should not defer thinning of similar stands because of Armillaria root disease. West J. Appl. For. 4(2):58-59, April 1989.

Inoculation of stumps with Hypholoma fasciculare as a possible means to control armillaria root disease

2000 ◽  
Vol 78 (1) ◽  
pp. 129-134 ◽  
Author(s):  
Bill Chapman ◽  
G Xiao
Keyword(s):  
Woody Debris ◽  
Root Disease ◽  
Tree Roots ◽  
Simple Method ◽  
Armillaria Ostoyae ◽  
Root Segments ◽  
Armillaria Root Disease ◽  
Hypholoma Fasciculare

Hypholoma fasciculare (Huds. ex Fr.) Kummer was paired with Armillaria ostoyae (Romagn.) Herink in a variety of ways in the laboratory and then it was inoculated onto A. ostoyae infected stumps in the field. The ability of H. fasciuclare colonies to overrun A. ostoyae colonies in culture was confirmed. Hypholoma fasciculare fully colonized discs of tree roots where A. ostoyae was well established, and prevented A. ostoyae from occupying root segments when both fungi were introduced simultaneously. A simple method for inoculating H. fasciculare into stumps is described, and data supporting successful field inoculations are presented. The ability of H. fasciculare to invade freshly killed stumps, even those occupied by Armillaria, is demonstrated, and it is speculated that the ability of this saprophyte to invade fresh stumps is dependent upon its inoculum potential.Key words: biocontrol, woody debris, fungal warfare, Armillaria ostoyae.

Visible versus actual incidence of Armillaria root disease in juvenile coniferous stands in the southern interior of British Columbia

2000 ◽  
Vol 30 (3) ◽  
pp. 405-414 ◽  
Author(s):  
D J Morrison ◽  
K W Pellow ◽  
D J Norris ◽  
A FL Nemec
Keyword(s):  
British Columbia ◽  
Host Response ◽  
Root Disease ◽  
Host Reaction ◽  
Intensity Of Infection ◽  
Climatic Regions ◽  
Forest Region ◽  
Armillaria Root Disease ◽  
The Relationship ◽  
Actual Incidence

The relationship between aboveground symptoms and belowground incidence of Armillaria ostoyae (Romagn.) Herink on conifers in 13- to 24-year-old stands was investigated at five sites in each of the dry, moist, and wet climatic regions in the Nelson forest region, British Columbia. All trees >1.3 m in height in 0.01-ha circular plots centred on a tree killed fewer than two or more than five years previously or located where there were no symptomatic trees were removed from the soil by an excavator. The location and host response at each A. ostoyae lesion on root systems were recorded. Significant differences in belowground incidence were seen among climatic regions and plot types, with distance from the centre of plots, and between planted and naturally regenerated trees. Belowground incidence was related to the percentage of putatively colonized stumps within and adjacent to plots. There were significant differences among climatic regions in the intensity of infection, host reaction to infection, and percentage of diseased trees showing aboveground symptoms. These results have implications for interpreting results of surveys for Armillaria root disease in juvenile stands and for tending of such stands.

Post-spacing mortality of lodgepole pine from armillaria root disease

2000 ◽  
Vol 76 (5) ◽  
pp. 753-757 ◽  
Author(s):  
Peter V. Blenis
Keyword(s):  
Key Words ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Root Disease ◽  
Precommercial Thinning ◽  
Armillaria Ostoyae ◽  
Pine Regeneration ◽  
Significant Difference ◽  
Percent Mortality ◽  
Armillaria Root Disease

To evaluate the threat of armillaria root disease in precommercially thinned lodgepole pine (Pinus contorta var. latifolia), a total of 66 15 × 15-m plots were established in dense lodgepole pine regeneration, 18 to 21 years after harvest, on three infested sites near Hinton, Alberta. Three treatments (2.5-m spacing, 1.5-m spacing and an unspaced control) were randomly applied to plots having similar densities and levels of mortality. After 11 years there was no significant difference among the treatments in cumulative percent mortality. Based on observed levels of mortality, it would appear that spacing need not be avoided in infested stands, although it likely would be prudent to space more closely than 2.5 m in younger stands and in parts of stands having more than 5–10% mortality. Key words: precommercial thinning, spacing, armillaria root disease, Armillaria ostoyae

The spatial distribution of Armillaria root disease in an uneven-aged, spatially clumped Douglas-fir stand

1995 ◽  
Vol 25 (6) ◽  
pp. 1008-1016 ◽  
Author(s):  
Bart J. Van Der Kamp
Keyword(s):  
Root Systems ◽  
Douglas Fir ◽  
Root Disease ◽  
Inoculum Potential ◽  
Partial Cutting ◽  
Infected Tree ◽  
Tree Removal ◽  
Spatial Domains ◽  
Armillaria Root Disease ◽  
Distributed Analysis

The location, species, and infection status of all trees and stumps in nine 40 by 40 m plots located in a single large Armillaria root disease (caused by Armillariaostoyae (Romagnesi) Herink) infested area in the Interior Douglas-fir Zone in British Columbia were recorded. The area was logged to a diameter limit in 1963 and then left undisturbed. Spatial analysis using variance over mean ratios of number of trees per grid square for a series of grid sizes showed that stumps were randomly distributed, trees were strongly clumped, and infected trees occurred in small clumps that were themselves randomly distributed. Analysis of intertree distances showed that clumps of infected trees ranged from 1 to 29 trees (average 3.2 trees). Incidence of infection did not decline with distance from old stumps. Infection incidence in spatial domains surrounding each stump ranged from 0 to 100%. Nevertheless, variation in incidence among stump domains could not be attributed to variation in inoculum potential at the time of logging. It is concluded that in the experimental area, 30 years after the last major disturbance by partial cutting, Armillaria occurs in small domains, largely on the root systems of trees regenerated since logging. In these circumstances, bridge tree removal spacing, which removes all trees from a band around each infected tree, may isolate most of the viable Armillaria inoculum colonies from the remainder of the stand.

scholarly journals Armillaria Root Disease Inoculum Remaining in Young Ontario Conifer Plantations Following Root Raking or Madge Rotoclearing

1998 ◽  
Vol 15 (4) ◽  
pp. 191-196 ◽  
Author(s):  
Johann N. Bruhn ◽  
Jeanne D. Mihail ◽  
Timothy R. Meyer
Keyword(s):  
Woody Debris ◽  
Site Preparation ◽  
Root Disease ◽  
Northern Ontario ◽  
Fallow Period ◽  
Disease Mortality ◽  
Lethal Infection ◽  
Woody Root ◽  
Armillaria Root Disease ◽  
Apparently Healthy

Abstract Armillaria ostoyae causes a destructive root disease in northern conifers. Most infections result from root invasions by rhizomorphs growing through the soil from previously colonized stump and woody root debris. Armillaria longevity in woody debris is related to the colonized volume. Stump and root removal by root raking alone often does not satisfactorily reduce subsequent root disease mortality. This investigation characterized residual woody debris volumes in three conifer seed orchards in northern Ontario. Site preparation for stump and root removal in two of the orchards consisted of root raking alone, vs. Madge Rotoclear™ treatment ("rotoclearing") in the third orchard. Fallow periods between site preparation and planting were 1, 5, and 8 yr in the three orchards, respectively. Mortality related to colonized residual woody debris is continuing in the raked orchards, but appears to have ended in the rotocleared orchard. Root systems of 32 orchard trees recently killed by Armillaria root disease and 9 apparently healthy (otherwise comparable) trees were excavated. Regardless of site preparation method, Armillaria-killed trees were associated with greater total volumes of residual woody debris (comprising larger pieces on average) than were healthy trees. Also, healthy trees in the rotocleared orchard were associated with smaller debris pieces on average than were healthy trees in the root-raked orchard. Size of individual woody debris pieces which contained viable A. ostoyae was highly variable. Even small pieces of colonized debris close to a root crown were apparently capable of causing lethal infection. Nevertheless, compared to root raking, rotoclearing apparently breaks A. ostoyae-colonized woody debris into smaller pieces resulting in more rapid displacement of A. ostoyae. We conclude that rotoclearing followed by a fallow period of 8 yr before planting merits consideration as an inoculum reduction treatment for site preparation. A 10 yr fallow period might have prevented nearly all root disease mortality under the conditions of this study. North. J. Appl. For. 15(4):191-196.

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