Progress 04/15/99 to 06/17/05
Outputs
A variety of factors are causing decline of Pacific madrone (Arbutus menziesii) in the Puget Sound region including diseases. Some trees, however, still remain healthy and it is unclear why they do. We investigated the idea that symbiotic associations between the roots of madrone and soil-dwelling fungi may make the trees less susceptible to disease, either directly or by providing physical links to nearby Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) trees. Based on indirect evidence, there was a tendency for healthy madrones to occur in dry, nitrogen-rich sites.
Impacts
Although we still have not solved the puzzle of why madrones are declining while others are healthy in the Puget Sound region it appears that management activities have interacted with diseases to exacerbate the problem. Overwatering and fertilization should be avoided if madrones are to remain healthy
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
A variety of factors are causing decline of Pacific madrone (Arbutus menziesii) in the Puget Sound region including diseases. Some trees, however, still remain healthy and it is unclear why they do. We are investigating the idea that symbiotic associations between the roots of madrone and soil-dwelling fungi may make the trees less susceptible to disease, either directly or by providing physical links to nearby Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) trees. Based on indirect evidence, there is a tendency for healthy madrones to occur in dry, nitrogen-rich sites.
Impacts
Although we still have not solved the puzzle of why madrones are declining while others are healthy in the Puget Sound region it appears that management activities have interacted with diseases to exacerbate the problem. Overwatering and fertilization should be avoided if madrones are to remain healthy
Publications
- 1. Trudell, S. A., E. T. Cline, M. Elliott and R. L. Edmonds. 1999. Possible role of mycorrhizas in resistance to decline in Arbutus menziesii. p. 130-135 in A. B. Adamas and C. W. Hamilton (eds). The Decline of the Pacific Madrone (Arbutus menziesii Pursh): Current Theory and Research. Center for Urban Horticulture, University of Washington, Seattle, WA. 2. Elliott, M., R. L. Edmonds, and S. Mayer. 2002. Role of fungal diseases in decline of Pacific madrone. Northwest Science 76(4): 293-303.
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Progress 10/01/02 to 09/30/03
Outputs
A complex set of factors is causing decline of Pacific madrone (Arbutus menziesii (Pursh)) in the Puget Sound region. Yet, some trees remain healthy and it is unclear why they do. We are investigating the hypothesis that symbiotic associations between the roots of madrone and soil-dwelling fungi may make the trees less susceptible to disease, either directly or by providing physical links to nearby Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) trees. In this portion of the overall study, our objectives were to determine whether: 1) madrones growing near Douglas-firs are healthier than madrones not growing near Douglas-firs; 2) the composition of the vegetation surrounding healthy madrones differs from that around unhealthy madrones; and 3) selected environmental factors at healthy madrone sites differ from those at unhealthy madrone sites. At Lincoln Park, Seattle, we surveyed the vegetation within 20 plots representing the four possible
combinations of healthy/unhealthy madrones and presence/absence of Douglas-fir, and analyzed the data using classification, ordination, soil nutrient indicator index, and soil moisture indicator index methods. There was no apparent relationship between madrone health and the composition of the surrounding vegetation, including the presence of Douglas-fir. Based on indirect evidence (SNII and SMII), there is a tendency for healthy madrones to occur in dry, nitrogen-rich sites. However, this indirect evidence cannot be considered conclusive and it should be substantiated by acquisition of direct data on soil nitrogen and moisture in relation to madrone health.
Impacts
There was no apparent relationship between madrone health and the composition of the surrounding vegetation, including the presence of Douglas-fir.
Publications
- No publications reported this period
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Progress 10/01/01 to 09/30/02
Outputs
A complex set of factors is causing decline of Pacific madrone (Arbutus menziesii Pursh) in the Puget Sound region. Yet, some trees remain healthy and it is unclear why they do. We are investigating the hypothesis that symbiotic associations between the roots of madrone and soil-dwelling fungi may make the trees less susceptible to disease, either directly or by providing physical links to nearby Douglas fir (Pseudotsuga menziesii (Mirbel) Franco) trees. In this portion of the overall study, our objectives were to determine whether: 1) Madrones growing near Douglas fir trees are healthier than madrones not growing near Douglas firs; 2) The composition of the vegetation surrounding healthy madrones differs from that around unhealthy madrones; and 3) Selected environmental factors at healthy madrone sites differ from those at unhealthy madrone sites. At Lincoln Park, Seattle, we surveyed the vegetation within 20 plots representing the four possible
combinations of healthy/unhealthy madrones and presence/absence of Douglas-fir, and analyzed the data using classification, ordination, soil nutrient indicator index, and soil moisture indicator index methods. There was no apparent relationship between madrone health and the composition of the surrounding vegetation, including the presence of Douglas fir. Based on indirect evidence (SNII and SMII), there is a tendency for healthy madrones to occur in dry, nitrogen-rich sites. However, this indirect evidence cannot be considered conclusive and it should be substantiated by acquisition of direct data on soil nitrogen and moisture in relation to madrone health.
Impacts
There was no apparent relationship between madrone health and the composition of the surrounding vegetation, including the presence of Douglas fir.
Publications
- Trudell, S. A., M. Elliott, E. Cline and R. L. Edmonds. 2000. The health of Pacific madrone and its relationship to the presence of Douglas-fir, mycorrhizae and fertilization. A report to Save Magnolia's Madrones, 1910 Edgmont Place W., Seattle, WA 98199. City of Seattle Depart of Parks Consultant Agreements 118566 and 118567.
- Elliott, M., R. L. Edmonds, and S. Mayer. 2002. Role of fungal diseases in decline of Pacific madrone. Northwest Science 76(4): 293-303.
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Progress 10/01/00 to 09/30/01
Outputs
Part A of the study concluded: Pacific madrone (Arbutus menziesii Pursh) has been declining in urban areas in the Puget Sound area due to a canker disease caused by the fungus Nattrassia mangiferae. Environmental stress is important in making the trees susceptible to disease. Stress caused by high available soil nitrogen is examined in this study. Madrones growing alone and in mixed stands with conifers were compared with respect to tree health and soil conditions including pH, moisture, and net nitrification. Tree health was determined by percent foliage relative to diameter and amount of disease from canker and branch dieback. Root tips of madrones were examined for mycorrhizae. Madrones growing in mixed stands had more mycorrhizal morphotypes. There was a trend towards lower available nitrogen in the soil in mixed stands. Unhealthy madrones growing with conifers had the lowest soil pH. Soils near unhealthy madrones had higher net nitrification rates than did soils
near healthy madrones. It is possible that increased nitrogen in the soil reduces mycorrhizal colonization of roots and negatively affects tree health. Part B of the study continues: A complex set of factors is causing decline of Pacific madrone (Arbutus menziesii Pursh) in the Puget Sound region. Yet, some trees remain healthy and it is unclear why they do. We are investigating the hypothesis that symbiotic associations between the roots of madrone and soil-dwelling fungi may make the trees less susceptible to disease, either directly or by providing physical links to nearby Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) trees. In this portion of the overall study, our objectives were to determine whether: 1) madrones growing near Douglas-firs are healthier than madrones not growing near Douglas-firs; 2) the composition of the vegetation surrounding healthy madrones differs from that around unhealthy madrones; and 3) selected environmental factors at healthy madrone sites differ
from those at unhealthy madrone sites. At Lincoln Park, Seattle, we surveyed the vegetation within 20 plots representing the four possible combinations of healthy/unhealthy madrones and presence/absence of Douglas-fir, and analyzed the data using classification, ordination, soil nutrient indicator index, and soil moisture indicator index methods. There was no apparent relationship between madrone health and the composition of the surrounding vegetation, including the presence of Douglas-fir. Based on indirect evidence (SNII and SMII), there is a tendency for healthy madrones to occur in dry, nitrogen-rich sites. However, this indirect evidence cannot be considered conclusive and it should be substantiated by acquisition of direct data on soil nitrogen and moisture in relation to madrone health.
Impacts
Part A: Increased nitrogen in the soil reduces mycorrhizal colonization of Pacific madrone roots. Part B: There was no apparent relationship between madrone health and the composition of the surrounding vegetation, including the presence of Douglas-fir.
Publications
- No publications reported this period
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Progress 10/01/99 to 09/30/00
Outputs
Pacific madrone (Arbutus menziesii Pursh) has been declining in urban areas in the Puget Sound area due to a canker disease caused by the fungus Nattrassia mangiferae. Environmental stress is important in making the trees susceptible to disease. Stress caused by high available soil nitrogen is examined in this study. Madrones growing alone and in mixed stands with conifers were compared with respect to tree health and soil conditions including pH, moisture, and net nitrification. Tree health was determined by percent foliage relative to diameter and amount of disease from canker and branch dieback. Root tips of madrones were examined for mycorrhizae. Madrones growing in mixed stands had more mycorrhizal morphotypes. There was a trend towards lower available nitrogen in the soil in mixed stands. Unhealthy madrones growing with conifers had the lowest soil pH. Soils near unhealthy madrones had higher net nitrification rates than did soils near healthy madrones.
Impacts
It is possible that increased nitrogen in the soil reduces mycorrhizal colonization of roots and negatively affects tree health.
Publications
- Elliott, M. E. Cline, S. Trudell, and R. L. Edmonds. 2000. Influence of soil nitrogen and mycorrhizae on Pacific madrone decline. Paper presented at the joint meeting of the Canadian Phytopathological Society and the Pacific Division of the American Phytopathological Society, June 18-21, 2000, Victoria, BC, Canada (Abstract).
- Trudell, S. A., M. Elliott, E. Cline and R. L. Edmonds. 2000. The health of Pacific madrone and its relationship to the presence of Douglas-fir, mycorrhizae and fertilization. A report to Save Magnolia's Madrones, 1910 Edgmont Place W., Seattle, WA 98199. City of Seattle Depart of Parks Consultant Agreements 118566 and 118567.
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Progress 10/01/98 to 09/30/99
Outputs
Fertilization, irrigation, physical injury, soil compaction, exposure, herbicides, and air pollutants have caused stress in Pacific madrone (Arbutus menziessii) in the Puget Sound region. We have been working on understanding the causes of madrone decline and have found it to be a combination of environmental stresses and disease organisms. Madrones growing near Douglas-fir trees appear to be healthier. The objectives of this study are to: (1) quantitatively assess the apparent relationship between madrone health and the proximity of Douglas-fir trees using a tree health rating scale developed for a variety of sites in the Puget Sound area, and (2) determine the influence of fertilization on cankering in young madrone trees.
Impacts
(N/A)
Publications
- No publications reported this period
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