Browsing by Subject "oak wilt"
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Item Data and Code for Mechanistic links between physiology and spectral reflectance enable pre-visual detection of oak wilt and drought stress(2024-01-04) Sapes, Gerard; Schroeder, Lucy; Scott, Allison; Clark, Isaiah; Juzwik, Jennifer; Montgomery, Rebecca; Guzman Q., J. Antonio; Cavender-Bares, Jeannine; gsapes@ufl.edu; Sapes, Gerard; University of Minnesota; University of Florida; Northern Research Station, USDA Forest ServiceTree mortality due to global change-including range expansion of invasive pests and pathogens- is a paramount threat to forest ecosystems. Oak forests are among the most prevalent and valuable ecosystems both ecologically and economically in the United States. There is increasing interest in monitoring oak decline and death due to both drought and the oak wilt pathogen (Bretziella fagacearum). We combined anatomical and ecophysiological measurements with spectroscopy at leaf, canopy, and airborne levels to enable differentiation of oak wilt and drought, and detection prior to visible symptom appearance. We performed an outdoor potted experiment with Quercus rubra saplings subjected to drought stress and/or artificially inoculated with the pathogen to detect and distinguish both types of stressors. We also performed a field experiment where we validated the capacity of spectral reflectance models to predict physiological status and distinguish oak wilt from healthy trees. The data and code provided here address these goals.Item Impacts of Prescribed Burns and Severe Weather Events on Oak Wilt Transmission in Central Minnesota(2020-12) Ostlie, JamesEcological disturbances of a region shape the landscape and influence ecosystem structure and function. However, in a rapidly changing world, newly introduced disturbances such as diseases and pests interact with historical disturbance regimes in unknown ways. The purpose of this thesis was to identify relationships between oak wilt, a catastrophic disease of oak trees introduced to Minnesota in the 1940s, and two historical disturbances of central Minnesota: low intensity fires and severe weather events. 1. The relationship between fire frequency and oak wilt occurrence was explored using a prescribed burning program at Cedar Creek Ecosystem Science Reserve. Using data collected from a census of 1,700 oak trees located on 28 different burn plots, two descriptive models were created: a logistic regression model to describe the probability of oak wilt presence and a Poisson regression model to describe density of stems with oak wilt. High fire frequency plots had lower oak wilt probability and oak wilt stem density than low fire frequency plots. Oak wilt presence was lower in high fire frequency plots than low fire frequency plots as well. These results suggest there is a relationship between high fire frequency and reduced probability of oak wilt presence and oak wilt stem densities. This relationship provides preliminary support for the use of prescribed burning as a possible management tool in conjunction with existing control measures. 2. The relationship between severe weather events (wind speeds > 50 knots and/or recorded hail amounts) and new oak wilt infection site was examined using NOAA’s severe weather events database and Minnesota DNR oak wilt aerial surveys for Anoka County. New oak wilt pocket formation occurred more frequently in areas where a severe weather event occurred the previous year. These results suggest severe weather events increase the probability of aboveground transmission of oak wilt via insect vectors and the likelihood of new oak wilt pocket formation. This relationship can be used to prioritize recently storm-damaged areas for more focused surveying in order to increase the success of early oak wilt detection. The relationships between fire frequency, severe weather events, and oak wilt presented within this thesis provide a framework for future adaptations and research to further inform oak wilt detection and management practices.Item Leaf and canopy spectra, symptom progression, and physiological data from experimental detection of oak wilt in oak seedlings(2019-04-26) Fallon, Beth; Yang, Anna; Nguyen, Cathleen; Armour, Isabella; Juzwik, Jennifer; Montgomery, Rebecca A.; Cavender-Bares, Jeannine; eafallon@gmail.com; Fallon, Beth; University of Minnesota, Department of Ecology, Evolution, and Behavior; University of Minnesota, Department of Forestry; US Forest Service Northern Research StationThese data were collected as part of an experimental effort to accurately detect oak wilt infections in oak seedlings using remote sensing tools and to differentiate that disease stress from other mechanisms of tree decline. Oak wilt disease causes rapid mortality in oaks in the central and eastern United States. Management of the disease requires early diagnosis and tree removal to prevent fungal spread. Hyperspectral tools provide a potential method of early remote diagnosis, but accurately differentiating oak wilt from other agents of oak decline is integral to effective management. We conducted experiments (2017 and 2018) on two year old seedlings of Quercus ellipsoidalis and Q. macrocarpa in which treatments were 1) maintained as healthy individuals, 2) subjected to chronic drought, or inoculated 3) stems with oak wilt fungus (Bretziella fagacearum, a fungal vascular wilt) or 4) leaves with bur oak blight fungus (Tubakia iowensis, a fungal leaf pathogen). We measured leaf and whole plant hyperspectral reflectance (350 to 2400nm, Spectra Vista HR 1024i spectroradiometer (Spectra Vista Corporation, New York, USA)), gas exchange (LI-6440XT with a leaf chamber fluorometer attachment (LI-COR Environmental, Nebraska, USA)), and tracked symptom development in repeated measures of seedlings over the course of each experiment. In 2018, we explicitly measured spectral reflectance and gas exchange on both symptomatic and green leaves, as available and we also measured collected thermal images of leaves twice during the experiment (2018 only).Item Mechanistic links between physiology and spectral reflectance enable pre-visual detection of oak wilt and drought stress(Proceedings of the National Academy of Sciences, 2024-02) Sapes, Gerard; Schroeder, Lucy; Scott, Allison; Clark, Isaiah; Juzwik, Jennifer; Montgomery, Rebecca; Guzmán Q., J. Antonio; Cavender-Bares, JeannineTree mortality due to global change—including range expansion of invasive pests and pathogens—is a paramount threat to forest ecosystems. Oak forests are among the most prevalent and valuable ecosystems both ecologically and economically in the United States. There is increasing interest in monitoring oak decline and death due to both drought and the oak wilt pathogen (Bretziella fagacearum). We combined anatomical and ecophysiological measurements with spectroscopy at leaf, canopy, and airborne levels to enable differentiation of oak wilt and drought, and detection prior to visible symptom appearance. We performed an outdoor potted experiment with Quercus rubra saplings subjected to drought stress and/or artificially inoculated with the pathogen. Models developed from spectral reflectance accurately predicted ecophysiological indicators of oak wilt and drought decline in both potted and field experiments with naturally grown saplings. Both oak wilt and drought resulted in blocked water transport through xylem conduits. However, oak wilt impaired conduits in localized regions of the xylem due to formation of tyloses instead of emboli. The localized tylose formation resulted in more variable canopy photosynthesis and water content in diseased trees than drought-stressed ones. Reflectance signatures of plant photosynthesis, water content and cellular damage detected oak wilt and drought 13 days before visual symptoms appeared. Our results show that leaf spectral reflectance models predict ecophysiological processes relevant to detection and differentiation of disease and drought. Coupling spectral models that detect physiological change with spatial information enhances capacity to differentiate plant stress types such as oak wilt and drought.Item Minnesota Shade Tree Advocate newsletter, volume 2, issue 2, spring 1998(1999) Minnesota Shade Tree Advisory CommitteeItem Minnesota Shade Tree Advocate newsletter, volume 3, issue 1, winter 2000(2000) Minnesota Shade Tree Advisory CommitteeItem Minnesota Shade Tree Advocate newsletter, volume 6, issue 2, spring 2004(2004) Minnesota Shade Tree Advisory Committee