| Title |
Investigators | Department | Objectives | Approach Keywords | Progress Reports | Impact Statements | Publications | |
Project * COL00745 | |
| Title | Interactions of Environmental Conditions with Forest and Shade Tree Diseases |
| Investigator(s) | Jacobi, WR; |
| Department | Bioagricultural Sciences and Pest Mgmt. |
| Objectives | A. This project will determine the relationship of environmental conditions to the health of roadside and riparian trees. B. This project will determine the environmental conditions that affect the spatial distribution of conifer diseases |
| Approach | Roadside surveys and plots will assess the impact of salt on vegetation. Data will be collected to improve BMPs to reduce the impact of salt. Stream sampling will determine if salt is moving to streams. Controlled green house studies will determine dose/response relationships of native woody plants and salt concentrations. An extensive field survey of white pine blister rust incidence and impact in WY will be used to model the potential impact of the disease in uninfested areas of Colorado and Wyoming. Modeling will include pine and Ribes host condition, site factors, and weather conditions promoting the disease. |
| Keywords | Forest health, Salt, Exotic disease, Invasive disease, High elevation, Riparian habitat |
| Progress Reports | |
| 1994 | Research completed this year included studies on the effect of oxygen deprivation on resistance of honeylocust (Gleditsia triacanthos) to Thyronectria austro-americana induced cankers. Potted trees grown in a shade house for two growing seasons with one set over watered and one set receiving normal water amounts. Inoculations were made in June and August and canker sizes recorded weekly for 6-8 weeks. Data analysis and manuscript preparation of this study will occur in 1995. Due to a shortage of funds, a new research nursery was established in 1994. Funding for irrigation equipment and other aspects of a turf and shade tree research system was obtained in late 1994. |
| 1995 | Research completed this year included the preparation of two manuscripts on past studies. One manuscript has been submitted to Plant Disease and the other to the Journal of Aboriculture. All other time devoted to woody ornamental studies involved planning, purchasing equipment, and installing a 5 acre turf and tree irrigation study area with turf type irrigation. The study area consists of 9 irrigation blocks that can be controlled separately. Additional funding is being sought to buy trees to complete this research facility. New research was initiated this year that concerns predicting the occurrence and severity of Armillaria root disease on ponderosa pine based on soil type, meteorological data and past disturbance. This study is in cooperation with faculty of three departments at Colorado State University and two branches of the U.S. Forest Service and is located in the Black Hills National Forest. |
| 1996 | Progress included the completion of the Tree and Turf research facility, publication of manuscripts and abstracts, initiation of a study on the pathogenicity of local Cytospora strains, a survey of Colorado's green ash for the presence of the causal agent of ash yellows, continuation of an IPM program for nurseries, and continuation of a study of the spatial relationship of Armillaria root disease and various environmental parameters. At the Tree and Turf research facility, over 600 trees representing four species were planted and the irrigation system completed. We have initiated a study to look at the pathogenicity of cytospora isolates from green ash, aspen, Siberian elm, cottonwood, willow, and alder. We will determine if the fungus found on one host can initiate cankers on other hosts. This information will aid in the management of this serious canker disease. In cooperation with six other states we completed a survey of green ash througout Colorado for the presence of the causal agent of ash yellows. The ash yellos phytoplasma was detected at all sample locations. We continued sampling nurseries for disease occurrence and the production of spores of several foliar diseases to provide nursery managers with better means of detecting and managing diseases. Our studies on the spatial occurrence of Amillaria root disease and environment factors are continuing. Current analysis indicates precipitation, slope, aspect and elevation can explain much of the occurrence of the disease. |
| 1997 | Activities related to this project include the completion of the Tree and Turf Research Facility, publication of one manuscript, completion of a M.S. thesis on Armillaria root disease, completion of research on a study of the pathogenicity of local Cytospora fungal strains, continuation of an IPM program for nurseries and continuation of a study on the spatial relationship of Armillaria root disease in the Black Hills and various environmental parameters. The Tree and Turf Research Facility was completed this year with the establishment of turf, installation of soil access tubes for soil moisture determinations and refining of the irrigation system. Base line data on tree size, leaf area, and soil moisture were collected. The study on Cytospora fungal strains was completed this summer. Based on preliminary results, we have found at least three distinct species of Cytospora based on pathogenicity tests. This epidemiological information will be helpful when trying to manage the disease in nurseries and landscapes. We continued sampling for disease occurrence and spore production of several foliar diseases of poplars as part of our Nursery IPM study. Our study of Armillaria root disease indicated that stands with the disease had more stumps, lower basal area, more saplings and seedlings than stands without the disease. This implies that recently regenerated areas have a higher incidence of disease. We are currently finishing our analysis of the relationship of soils, past management activities and Armillaria root disease incidence. |
| 1998 | Activities related to this project include the completion of the first year of data collection on tree and turf growth and water usage from the Tree and Turf Research Facility, completion of a M.S. thesis on Cytospora canker disease, continuation of an IPM program for nurseries, initiation of a study of susceptibility of trees to canker fungi and a study of the hazard of disease fungi residing in wood chip mulch at the Turf and Tree Facility, and continuation of a study on the spatial relationship of Armillaria root disease in the Black Hills. AT the Tree and Turf Research facility data on tree size, leaf area, turf growth and soil moisture was collected. The study on Cytospora fungal strains found at least three distinct species of Cytospora based on pathogenicity tests. This epidemiological information will be helpful when trying to manage the disease in nurseries and landscapes. We continued sampling for disease occurrence and spore production of several foliar diseases of poplars as part of our Nursery IPM study. Our study of Armillaria root disease is currently being finished with analysis of the relationship of soils, past management activities, forest structure and Armillaria root disease incidence. |
| 1999 | Activities related to this project include; collecting a second year of data on tree and turf growth and water usage from the Tree and Turf Research Facility, continuation of an IPM study for poplar leaf spots, continuation of a study of susceptibility of trees to canker fungi and a study of the duration of canker fungi residing in wood chip mulch, and continuation of a study on the spatial relationship of Armillaria root disease in the Black Hills. At the Tree and Turf Research facility tree diameter was affected by irrigation amounts (40, 80 and 160% ET), but not tree heights, or turf growth. We analyzed spore production and infection data for foliar diseases of aspen and poplar trees. Infection timing and secondary spore production and relationship of precipitation was determined for Marssonina and Septoria leaf spots. This information should help improve management of these diseases and reduce fungicide use. We will be writing a manuscript on these results. |
| 2000 | Problem: Do fungal canker pathogens remain viable in uncomposted wood chip mulch and thus pose a threat to landscape trees? Study methods: Honeylocust branches were inoculated with a canker fungus Thyronectria austro-americana and sections placed in mulch around trees at our Tree and Turf Research Facility. Branch sections were collected periodically over 59 weeks and fungus was isolated from these samples. Results: We found the fungus was still viable in over 50% of the branch section even after 59 weeks. The location within or on the surface of the mulch seems to affect the viability of the fungus but our results are variable. Additional activities related to this project include; collecting a third year of data on tree and turf growth and water usage from the Tree and Turf Research Facility, analysis of data from an IPM study of poplar leaf spots, continue analyzing data from a study on the spatial relationship of Armillaria root disease in the Black Hills and the continuation of a study of the impact of variable moisture availability to cottonwoods along an irrigation canal. |
| 2001 | Problem: What are the relationships of soil moisture along an intermittent irrigation canal and the water status of cottonwood trees growing along the canal. Study methods: Soil moisture and predawn cottonwood leaf water potentials were collected weekly from four locations along an irrigation canal. Some trees were exposed to irrigation water while others did not via pass-through pipes that disallowed water in that section. Precipitation data was also collected at these sites. Results: This is a progress report on a long-term study. The best estimate of when cottonwood trees start to be drought "stressed" would be when leaf water potentials are less than -0.3 MPa. It has taken 6-8 weeks from when the canal was turned off for trees to reach -0.3 MPa. Trees recover or reduce water stress 24 hr after adding water in the canal but we do not know how long this recovery lasts. We do not know how long water needs to be present to relieve drought stress for long periods. It appears that soil moistures > 20% will keep trees non-stressed (> -0.3 MPa) and soil moistures less than 10% will allow leaf water potential to be above -0.30 MPa. Precipitation of 1 inch or more increases leaf water potentials but the response is short lived. Additional activities related to the overall project include; collecting a fourth year of data on tree and turf growth, tree susceptibility to canker fungi and water usage from the Tree and Turf Research Facility, continue analyzing data from a study on the spatial relationship of Armillaria root disease in the Black Hills and the continuation of a study of the duration of tree pathogens in uncomposted wood mulch. |
| 2002 | Problem: Uncomposted wood chips from urban tree removals or wood waste are often used as landscape mulches. Many times trees that are removed are in poor health and contain plant pathogens. Wood waste from pallets and other packing materials may contain indigeneous as well as exotic plant pathogens. Study Methods: A study was initiated to determine how long a common fungal plant pathogen, Thyronectria austro-americana, the cause of Thyronectria Canker in honeylocust trees, could survive in uncomposted wood chip mulch under various irrigation regimes. Cankered wood pieces remained a source of inoculum for 143 weeks after placement around trees in an irrigated landscape. T. austro-americana recovered from cankered wood pieces after 98-weeks on top of or in mulch layers, did produce cankers on inoculated branches of honeylocust trees. Placement on the mulch surface or buried in the mulch did affect recovery of the fungus depending on the length of time after placement. Amount of irrigation applied to the mulch did not affect the recovery of the fungus. Thus, mulch derived from honeylocust trees infected with the fungus T. austro-americana, should not be placed around honeylocust trees in urban landscapes. |
| 2003 | Problem:As land uses change and irrigation canals are not used, water availability for cottonwood trees growing along irrigation canals decreases. Cottonwoods are an important resource in many riparian and urban landscapes since they may be the only large tree present. Information on how much water is needed and and when it is needed to keep these trees alive is a common issue in the west. To answer some of these questions, we are studying the water status of cottonwoods via water potentials, soil moisture using neutron probes and observation wells, along a 100 yr.-old irrigation canal that runs through metropolitan Denver. When water potentials are less than -0.3 MPa trees start to be stressed. What stress amount, duration and time of stress is needed to kill parts or whole trees is currently being evaluated. Trees recover 24 hr after water is added to the canal, but we do not know how long this recovery lasts. We do not know how long water needs to be present to relieve drought stress in mid summer. It appears that soil moisture > 20% will keep trees non-stressed (> -0.3 MPa) and soil moisture less than 10% will allow leaf water potential to decrease below -0.30 MPa. Precipitation events of 1 inch or more increased leaf water potentials but the response was short lived and an increase in soil moisture was not noted. |
| 2004 | We have made good progress on all objectives for the first year of the magnesium chloride project. We have surveyed over 230 miles of roadside vegetation and established 37 permanent plots along the roadside. We established 17 water monitoring sites in streams that have road drainage into them throughout Larimer and Grand counties and collected water samples every two weeks. For years, the primary vector of Ophiostoma novo-ulmi, the causal fungus of Dutch elm disease (DED) in American elm trees in Colorado has been Scolytus multistriatus, the European elm bark beetle. Recently, another exotic species of Scolytus, S. schevyrewi, the banded elm bark beetle, has been found in association with declining American elm trees along the Front Range of Colorado. The objective of this study was to determine if S. schevyrewi could be a potential vector of O. novo-ulmi. Isolation attempts were made from the two Scolytus species that emerged from the stem sections. Ophiostoma novo-ulmi was successfully isolated (4-67%) from S. schevyrewi and S. multistriatus. A high percentage (37 %) of adult S. schevyrewi beetles reared from three trees with Dutch elm disease carried O. novo-ulmi. This is no different that what we know about S. multistriatus, but reinforces the importance of rapid removal of tree with O. novo-ulmi. Thus the two Scolytus species appear to be efficient transporters of propagules of O. novo-ulmi. The infection of healthy elm trees by fungi carried by either insect is assumed to occur but further studies would be needed to show this relationship occurs. Problem: What is the distribution of the exotic disease white pine blister rust in Wyoming and does the disease vary with site and tree characteristics? A survey of limber pine health over the last three years provided data from 504 plots on 13 study areas on the Shoshone NF, Wind River Indian Reservation, BLM lands, Medicine Bow NF, and Roosevelt NF. We found 81% of the trees were healthy, 13.5% were dying and 5.4% were dead. The average incidence of white pine blister rust infected limber pine was 15.5% over all plots and 28% on infested plots. Tree size, crown class, elevation, slope position were related to rust incidence. This information will be used to develop hazard models for unifested areas of the Central Rocky Mts. These models will help predict the impact of this exotic disease on the important limber pine ecosystems in the Central Rocky Mts. This survey is the first landscape scale assessment of what impact white pine blister rust is and will have on ecosystems in the Rocky Mountains. |
| 2005 | Problem: Where will the exotic disease, white pine blister rust (WPBR), infest trees and cause significant damage as it moves into Colorado. Study methods: Predictive models of risk and hazard were developed, based on survey data of the rust impacts in WY where it has been moving and establishing for the last 5-25 years. Results: A survey of limber pine to determine the geographical distribution, incidence, and severity of WPBR, was performed in central and southeastern Wyoming and northern Colorado in 2002-2004. These data were used to develop a series of regression and categorical and regression tree analysis models to predict risk and hazard of WPBR in Colorado. Risk models predicting the presence of WPBR employed meteorological, Ribes (the alternate host), and tree size data and resulted in good agreement between predicted and actual rust presence. Models developed to predict disease pressure and hazard also employed meteorological, Ribes, and plot-level data. |
| 2006 | Problem: How can forest managers protect and reduce mortality of limber pine trees in a high value site when attacked by white pine blister rust. Study methods: This study tested the efficacy of both preventative (crown lifting) and pathological pruning of white pine blister rust on high value trees in recreation areas in Wyoming and Colorado. We found limber and bristlecone pines can be pruned to lift crowns and remove cankers up to 17 feet from the ground in 30 minutes or less with crews of 2 to 3 people. The long term results of the preventative and pathological pruning treatments will be available when the trees are reevaluated in 3- 5 years |
| Impact | |
| 1999 | Information generated by studies at the Tree and Turf Research Center on irrigation practices will reduce water usage, improve shade tree and turf health. Studies on leaf spot diseases of aspen and poplars will improve management of these diseases by providing information on when infection takes place in Colorado. This information will help reduce the use of fungicides. |
| 2000 | The fact that canker fungi can survive in wood chip mulch for over a year, including a winter, implies wood chip mulch could harbor and produce significant amounts of disease causing propagules. Thus diseased trees that are chipped should not be placed around similar species of landscape plants. We suspect if the chips were composted they would pose less of a threat to the trees. This research also implies that the practice of chipping wood pallets, crates, and dunage imported from other countries may move exotic pests into our landscapes. Further research is needed to confirm some of these issues. |
| 2001 | The amount of water and timing of the water availability needed to keep cottonwood trees from being drought stressed will be determined. Determining the relationships between soil moisture and the tree's water potential will help future management of trees in arid environments |
| 2002 | This information will be of use in preventing the introduction of exotic pathogens through the chipping of solid wood packing material. Our results suggest infested wood chips should be treated or modified before use in landscapes if pathogen inoculum is to be reduced. |
| 2003 | Information generated from this study will provide landscape and municipal managers the information on water needs to keep our native cottonwoods healthy. |
| 2004 | Information generated from this study will provide road and land managers the information on salt and the environment and how to mitigate any impacts. The vectoring of the Dutch elm disease fungus by the new exotic bark beetle- Banded Elm Bark Beetle provides important information for aborists and tree health management programs. The impact of white pine blister rust information will be used by land managers in deciding what restoration and management actions to take in regard to this exotic disease. |
| 2005 | These models were incorporated into the national RISK map system of the U.S Forest Service for regional and national level planning purposes. Region 2, Forest Health staff also incorporated the models, into an interactive stand level GIS. Local forest districts can now use these predictive GIS maps. |
| 2006 | These pruning techniques have been incorporated into USDA For. Service management guides for the management of limber pine. The techniques and findings were provided at several regional meetings in 2006 and placed on the laboratory web site. |
| Publications | |
| 1993 |
Guyon, J.C. 1993. Selected environmental stresses and two canker diseases of trees. M.S. Thesis, Colorado State University. 114 pp. Swift, C. W., Jacobi, W. R., Schomaker, M. E. and Leatherman, D. A. 1992. Environmental disorders of woody plants. Service in Action Sheet. Colo. State Univ. Extn. Serv. No. 2.932. |
| 1994 |
Jacobi, W.R., Kelly, E.F., Troendle, C.A., Angwin, P.A., Wettstein, C.A. 1993. Environmental Influences on Aspen Regeneration Failure. Phytopathology 83:1411 (abstract) Omdahl, D.W., Shaw, C.G., III, Jacobi, W.R., Wagner, T.C. 1993. Pathogenicity and Virulence of Armillaria ostoyae on Eight Forest Tree Species. Phytopathology 83:1365(abstract) |
| 1995 |
Jacobi, W. R. and zumBrunnen, J. R. 1995. Douglas-fir resistance to black stain root disease. In: Proceedings of the 43rd Annual Western International Forest Disease Work Conference. (Abstr.) Kerbs, S. T. and Jacobi, W. R. 1995. Long term flooding stress and Thyronectria Canker on Honeylocust trees. In: Proceedings of the 43rd Annual Western International Forest Disease Work Conference. (Abstr.) Omdal, D. W., Shaw, C. G., III, Jacobi, W. R., and Wager, T. C. 1995. Variation in pathogenicity and virulence of isolates of Armillaria ostoyae on eight tree species. Plant Dis . 79:939-944 |
| 1996 |
Guyon, J.C., Jacobi, W.R. and McIntyre, G.A. 1996. Effects of environmental stress on the development of Cytospora canker of aspen. Plant Dis. 80:1320-1326 Kallas, M.A., Jacobi, W.R., and Reich, R.M. 1996. Hazard rating model for Armillaria root disease in the Black Hills National Forest. In: Proceedings of the 44th Annual Western International Forest Disease Work Conference. (Abstr) Kallas, M.A., Jacobi, W.R., Reich, R.M. and Lundquist J.E. 1996. Use of geographic information systems to study Armillaria root disease distribution in the Black Hills. Phytopathology 86:Vol 11: S102 (Abstr). McIntyre, G.A., Jacobi, W.R. and Ramaley, A.W. 1996. Factors affecting Cytospora canker occurrence on aspen. J. Arboriculture 22:229-233 |
| 1997 |
Sclar, D.C., Cranshaw, W. S. and Jacobi, W.R. 1997. Integrated pest management practices in Colorado: A survey of woody plant nurseries and homeowners, 1995-96. Colorado State University , Tech. Bull. TB97-2. 17 pp |
| 1998 |
Burks, S., Jacobi, W.R. and McIntyre, G.A. 1998. Cytospora canker development on aspen in response to nitrogen fertilization. J. Arboriculture.24: 28-34 Jacobi, W.R., Kelly, E.F., Troendle, C.A., Angwin, P.A., Wettstein, C.A. 1998. Environmental conditions and aspen regeneration failure. USDA, For. Serv. Rocky Mt Reg., For. Health Management, Tech. Rep. R2-60 24pp |
| 1999 |
Bernard, K. E., Dennis, C. and Jacobi, W. R. 1999. Protecting trees during construction. Colorado State University, Cooperative Extension Fact Sheet 7.420. 4pp Francis, C., Jacobi, W. R. and Cranshaw, W. S. 1999. Pinyon pine diseases and insects. Colorado State University, Cooperative Extension Fact Sheet, 2.949. 8 pp Jacobi, W. R. 1999. Aspen and poplar leaf spots. Colorado State University, Cooperative Extension Fact Sheet 2.920. 4pp |
| 2000 |
Kepley, J. B., and Jacobi, W. R. 2000. Pathogenicity of Cytospora fungi and six hardwood species. J. Arboriculture. 26:326-332. Walla. J. A., Jacobi, W. R., Tisserat, N. A., Harrell, M, O., Ball, J. J., Neil, G. B., Reynard, D. A., Guo, Y. H. and Spiegel, L. 2000. Condition of green ash, incidence of ash yellows phytoplasmas, and their association in the Great Plains and Rocky Mountain regions of North America. Plant Dis. 84:268-274. |
| 2001 |
Colorado State University Cooperative Extension Service, 2000. Insects and Diseases of Woody Plants of the Central Rockies. Bulletin 506. 284 pp. W. R. Jacobi, Co editor Omdal, D. W., Jacobi, W. R. and Shaw, C. G. III. 2001. Estimating large-root biomass from breast-height diameters for ponderosa pine in northern New Mexico. Western J. Applied Forestry 16:18-21. Omdal, D. W., Shaw, C. G. III and Jacobi, W. R.. 2001. Evaluation of three machines to remove Armillaria-and Annosum- infected stumps. Western J. Applied Forestry 16:22-25. |
| 2002 |
Holly S. J. Kearns, William R. Jacobi, and Jeri Lyn Harris.. 2002. The Distribution of White Pine Blister Rust in Southeast Wyoming In: Proceedings of the 50th Annual Western International Forest Disease Work Conference. (Abstr.) Kearns, S. J. and Jacobi, W. R. 2001. Black stain root disease in the pinyon-juniper woodlands of southwestern Colorado. In: Proceedings of the 49th Annual Western International Forest Disease Work Conference.(Abstr.) W.R. Jacobi, S. Zeglen, J.A. Muir, R. S. Hunt. 2002. Black Stain Root Disease Mortality Rates on Douglas-fir in Coastal British Columbia. In: Proceedings of the 50th Annual Western International Forest Disease Work Conference.(Abstr.) |
| 2003 |
Kearns, H. S. J., Jacobi, W. R., Sullivan, K. and Geils, B. W. 2003. Is the alternate host for white pine blister rust present in Colorado? In: Proceedings of the 51th Annual Western International Forest Disease Work Conference. (Abstr.) Koski, R.D. and Jacobi, W. R. 2003. Tree pathogen survival in wood chip mulch. Phytopathology 93: S47 (Abstr.) Koski, R.D. and Jacobi, W. R. 2003. Tree pathogen survival in wood chip mulch. In: Proceedings of the 51th Annual Western International Forest Disease Work Conference. (Abstr.) Smith, E.L.; Geils, B.W.; Kearns, H.S.; and W.R. Jacobi. 2002. The biogeography of blister rust invasions: the challenges of new outbreaks. 2002 Ecological Society of America Annual Meeting; Symposium on "The Rapid Decline of White Pine Ecosystems of the West: Causes ,Consequences, and Restoration Strategies"; August 5-9, 2002, Tucson, AZ. (Abstr.) |
| 2004 |
Costello, S., Jacobi, W. R. and Negron, J. 2004. Evaluating traps and attractants for surveying adult woodborer populations in burned areas of the Black Hills, South Dakota. In: Proceedings of the 52nd Annual Western International Forest Disease Work Conference. (Poster Abstr.) Goodrich, B. A., Jacobi, W. R. and Koski, R. D. 2004. Meteorological aspects of white pine blister rust in Colorado and Wyoming. In: Proceedings of the 52th Annual Western International Forest Disease Work Conference. (Poster Abstr.) |
| 2005 |
H.S. J. Kearns and W. R. Jacobi. 2005. Impacts of black stain root disease in recently formed mortality centers in the pinon juniper woodlands of Southwestern Colorado Can. J. For. Res. 35: 461-471 H.S. J. Kearns, W. R. Jacobi, and D. W. Johnson. 2005. Persistence of pinyon snags and logs in Southwestern Colorado. Western Journal of Applied Forestry. 20: 247-252 Koski, R. and Jacobi, W. R. 2004. Tree pathogen survival in chipped wood mulch. J. Arboriculture 30:165-171 Omdal, D. W. Shaw, C. G. III, and Jacobi, W. R. 2004. Symptom expression in conifers infected with Armillaria ostoyae and Heterobasidion annosum. Can. J. For. Res. 34: 1210-1219 Walla, J. A., Jacobi, W. R. and R. A. Schmidt. 2003. Forest Pathology for the last century: An overview of the symposium. Phytopathology 93: 1037-1038 |