DETERMINING THE CAUSES OF ABIOTIC LEAF SCORCH: GETTING TO THE ROOT OF THE PROBLEM. By Phillip S. Kurzeja A THESIS Submitted to Michigan State University In partial fulfillment of the requirements For the degree of Plant Biology - Master of Science 2015 ABSTRACT DETERMINING THE CAUSES OF ABIOTIC LEAF SCORCH: GETTING TO THE ROOT OF THE PROBLEM. By Phillip S. Kurzeja Leaf scorch is a common symptom of declining trees in urban landscapes, especially Northern red oaks, Quercus rubra. Established trees with a known history of abiotic leaf scorch were systematically evaluated for depth of root flare, girdling root severity, soil compaction (resistance), soil nutrient profile, pH, and soil oxygen profile. Photosynthesis efficiency, leaf pressure potential, leaf conductance, leaf transpiration, and plant tissue nutrition were measured to examine differences in physiological function between scorched and non-scorched oaks on the same site and among sites. Leaf scorch was significantly positively correlated to planting depth. Planting depth was positively correlated to girdling roots and smaller DBH. However, leaf scorch was not significantly correlated with the presence of girdling roots. Soil treatment with micro-fine sulfur, and Mauget injections increased iron but not manganese in leaf nutrient levels. Scorched trees had smaller DBH, greater planting depth than non-scorched trees. Tree height and DBH was positively correlated with less compacted soils. Scorched leaves had a significantly higher temperature compared to non-scorched. Scorched trees had lower levels of manganese, and higher levels of zinc. Phosphorus, though deficient, showed a positive correlation to leaf scorch. Photosynthetic efficiency and leaf conductance data from 2009 and 2010 were highly similar. Scholander pressure chamber data from 2008 and 2009 were highly similar. A better understanding of the functional capabilities of girdling roots in oaks is needed to better interpret some results. For Stéphan and Josée Kurzeja iii ACKNOWLEDGEMENTS This research project was funded by the MSU GREEEN (Grant # GR08-077) to Dr. G. Adams, initiative with backing from the Michigan Nursery and Landscape Association (MNLA), for J. Paul Swartz, F. W. Telewski and G. Adams. Essential instrumentation had been funded by prior grants to F. W. Telewski. Supplemental funding was from USDA Forest Service Environmental Monitoring program on Bacterial Leaf Scorch to G. Adams. Funding was received from the W.J. Beal Botanical Garden for leaf and soil analyses. I wish to thank J. Paul Swartz and the MSU Landscape services, as well as Robert Gentry and Steve Adams of the city of Adrian, MI for contributing machinery. To Dr. Frank W. Telewski for being my major advisor, teacher, colleague and friend, thank you for everything you have done for me. Thanks also goes to Dr. Bert Cregg and Dr. Gerry Adams for being part of my committee. A very special thanks goes to Dr. Jameel “Habibi” Al-Haddad for assistance with statistical analysis. Last, but certainly not least is my wonderful and loving wife Kara, without her I could never have completed this work. iv TABLE OF CONTENTS LIST OF TABLES ..................................................................................................................................... vi LIST OF FIGURES ................................................................................................................................. viii CHAPTER 1 INTRODUCTION ........................................................................................................................... 1 CHAPTER 2 LITERATURE REVIEW ................................................................................................................ 6 CHAPTER 3 PAPER FOR PUBLICATION: Site Specific Causes of Abiotic Leaf Scorch in Urban Red Oaks (Quercus rubra) ............................................................................................................................. 15 ABSTRACT...................................................................................................................... 15 INTRODUCTION ............................................................................................................ 15 METHODS AND MATERIALS ...................................................................................... 18 Study Sites: ............................................................................................. 18 Above Ground Parameters ................................................................................... 19 Visual Scorch Rating (VSR): .................................................................. 19 Average Growth per Year (AGY): ......................................................... 20 Average Basal Area Growth Rate (BAGR): ........................................... 20 Soil Compaction (Pen (J/m)): ................................................................. 20 Soil pH: ................................................................................................... 21 Identification of Abiotic Stress: .............................................................. 21 Below Ground Parameters ................................................................................... 21 Air Spade Excavations: ........................................................................... 21 Planting Depth: ....................................................................................... 22 Percent Girdling Root (%GR): ............................................................... 22 Statistical Analysis: ................................................................................ 22 RESULTS ......................................................................................................................... 23 DISCUSSION ................................................................................................................... 23 CONCLUSION ................................................................................................................. 25 APPENDICES ........................................................................................................................................... 26 APPENDIX A: PHYSIOLOGICAL DATA .............................................................................................. 27 APPENDIX B: SOIL AND FOLIAR NUTRIENTS ................................................................................. 44 LITERATURE CITED ............................................................................................................................ 77 v LIST OF TABLES Table 1. Site Irrigation and Data Collected by Year: Based on observations from previous years, established oaks exhibiting scorch adjacent to non- scorched oaks of the same age at each site, growing in the same soil types were chosen. Site (AD) = Oak hill Cemetery, Adrian, MI. (BR1) = Jack Breslin Student Events Center, MSU, MI. (BR2) = Jack Breslin Student Events Center, MSU, MI. (SW) = Shaw Lane, MSU, MI. (FR) = Farm Lane, MSU, MI. (GR) = Grand River Ave, East Lansing, MI. (LB) = Main Library, MSU, MI. Irrigation: (Rain) natural rain fall, (Regulated Irr.) systems controlled irrigation, (Sporadic Irr.) a member of the landscape staff manually turned on and off a sprinkler system, when it was deemed necessary absent of any schedule or known interval. (X) = year that data was collected at each site and the type of irrigation received from 2008 through 2013………………………...56 Table 2. Pearson product moment correlation table: Correlation table comparing average basal area growth rate per year (BAGR), average growth per year (AGY), depth of original root flare (DORF) as measured from original soil surface to the top of the first tier, percent girdling root (%GR) is a measurement of the total percent of the root collar that is constricted by girdling roots compared to the total circumference of the base of the trunk, soil compaction (Pen (Joules/m)) or resistance of soil in the root zone quantified by determining soil resistance (impedance) to penetration and average visual scorch rating (VSR), rated as 0,1,2,or 3, for each tree at the seven sites………………………………………………..57 Table 3. Original pearson’s product moment correlation table: Correlation table comparing height (m), diameter at breast height (DBH), depth of original root flare (DORF) as measured from original soil surface to the top of the first tier, percent girdling root (%GR) is a measurement of the total percent of the root collar that is constricted by girdling roots compared to the total circumference of the base of the trunk, soil compaction (Pen (Joules/m)) or resistance of soil in the root zone quantified by determining soil resistance (impedance) to penetration and average visual scorch rating (VSR), rated as 0,1,2,or 3, for each tree at the seven sites. Due to the fact that the trees are not similar in age across sites it was important to change both height and DBH to correct for differences in age……………………..58 Table 4. Leaf temperature/Scholander (LpP) experiment correlation matrix: Correlation matrix comparing visual scorch rating (VSR) to leaf temperature and Scholander pressure chamber (LpP) readings…………………………………………………………………59 Table 5. Photosynthetic efficiency, PSII efficiency (Photo): Pearson product moment correlation matrix was performed comparing photosynthetic efficiency data averages collected in 2008, 2009, 2010 (Photo 2008), (Photo 2009) and (Photo 2010) respectively, across all sites and VSR. There was a non-significant relationship between VSR and Photo in all years. Also there was a non-significant relationship when 2008 was compared to 2009 or 2010 photosynthetic efficiency data sets. There was a negative correlation coefficient (r) = -0.517 and an extremely strong significant similarity between the 2009 and 2010 photosynthetic efficiency data sets with (p) = 0.000235………………………………………………………….59 Table 6. Stomatal conductance, leaf gas exchange (Cond): Pearson product moment correlation matrix was performed comparing stomatal conductance data averages collected in 2008, 2009, 2010 (Cond 2008), (Cond 2009) and (Cond 2010) respectively, across all sites and VSR. There was a non-significant relationship between VSR and Cond in all years. Also there was a non-significant relationship when Cond 2008 was compared to Cond vi 2009 or Cond 2010 data sets. There was an extremely strong correlation between the 2009 and 2010 stomatal conductance data sets with a positive correlation coefficient of (r) = 0.567 and an extremely strong significant similarity between the 2009 and 2010 stomatal conductance data sets with (p) = 0.0000496……………………………………………………………………………...60 Table 7. Scholander pressure chamber, leaf pressure potential (Schol): Pearson product moment correlation matrix was performed comparing Scholander pressure chamber data averages collected in 2008, 2009, 2010 (Schol 2008), (Schol 2009) and (Schol 2010) respectively, across all sites and VSR. There was a non-significant relationship between VSR and Schol in all years. Also there was a non-significant relationship between the Schol 2008 and Schol 2010 data sets, with similar results when Schol 2009 was compared to the Schol 2010 data. There was an extremely strong correlation between the 2008 and 2009 Scholander pressure chamber data sets with a positive correlation coefficient of (r) = 0.422 and strong significant similarity between the 2008 and 2009 Scholander pressure chamber data sets with (p) = 0.00924…………………………………………………………………………………………60 Table 8. Leaf temperature/Scholander experiment correlation matrix: A correlation matrix was used to compare visual scorch rating (VSR), leaf temperature, and leaf pressure potential (LpP) averages………………………………………………………………...61 Table 9. Correlation table for zinc (Zn) and visual scorch rating (VSR): Foliar nutrient (Zn) data collected from sites BR1 and BR2, compared to visual scorch rating…61 Table 10. Visual scorch rating (VSR) and leaf tissue nutrient analysis Pearson's correlations and foliar nutrient analysis levels compared to adequate levels looking for deficiencies: Numerical results of correlation matrix of all leaf tissue analysis nutrients compared to visual scorch rating (VSR) TOP ROW. Lower rows show results of leaf tissue nutrient analysis, comparing Manganese (Mn), Phosphorus (P), Magnesium (Mg), Potassium (K), Calcium (Ca), Iron (Fe), Copper (Cu), Boron (B) and zinc (Zn) listed here is parts per million (ppm) along with Nitrogen (N) and Sulphur (S) as a percent (%), to known adequate nutrient levels, denoted as either deficient yes (Y) or not deficient no (N)…………………………………………………...62 Table 11. Correlation table for soil (pH) and visual scorch rating (VSR): Soil pH data collected from sites BR1 and BR2, compared to visual scorch rating……………...62 Table 12. Soil pH levels and soil nutrient levels: Soil pH for sites BR1 and BR2 combined into (BR). Site FR is not included in this table, due to other treatments that were done to that site after preliminary work was completed……………..62 vii LIST OF FIGURES Figure 1. Sites BR1 and BR2: Of the original three sites established in 2008, the first site, known as (BR), which stands for Breslin Center, also known as the Jack Breslin Student Events Center on the campus of Michigan State University, was split into two sites which are referred to as (BR1) and (BR2)…………….63 Figure 2. Site FR The other original sites, Farm lane site on West side of Farm lane between East and West bound Shaw referred to as (FR)………………………………………………………………………….63 Figure 3. Site SW: Two new sites were added in 2010. The first new site consisted of 10 trees along East Shaw lane between the Wharton Center and Wilson Road on the campus of Michigan State University. The Shaw lane site is referred to as (SW)……………………………………………………………..64 Figure 4. Site GR: The second site established in 2010 was along Grand River Avenue, between M.A.C, and Bailey roads, referred to as (GR)…………………………………………………………………………64 Figure 5. Site LB: Finally in the fall of 2012, six more trees on the South side of the Michigan State University Main Library were added to the study referred to as (LB)……………………………………………………………………………………………….65 Figure 6. Visual scorch rating (VSR): A scorch rating of 0 is a green leaf with characteristics of no discoloration to very mild interveinal discoloration (mild chlorosis). A scorch rating of 1 is a green leaf with symptoms ranging from medium chlorosis to mild small brown necrotic spots. A scorch rating of 2 is a leaf with severe chlorosis, and or some brown papery necrotic spots that have partially merged but do not cross the vein areas of the leaf. A scorch rating of 3 is a leaf that has symptoms ranging from having severe necrotic areas to being covered with brown dry papery necrotic areas in the interveinal areas, with some areas expanding over the leaf veins. The final scorch rating 3 is a leaf that dries to a point that it curls in an involute manner………………………………………65 Figure 7. Photograph of mineral ring: Photograph of tree 90-06 site FR. Girdling roots exposed after air spading was performed, removing several inches of soil and mulch. Months after the air-spading took place, a persistent mineral deposit ring could be observed on the tree trunk marking the mulch depth. This was used to determine the soil and mulch level for depth of original root flare (DORF) measurements…..66 Figure 8. Correlation graph of visual scorch rating (VSR) and depth of original root flare (DORF): Average visual scorch rating (VSR), rated as 0,1,2,or 3, for each tree at the seven sites compared to the depth of original root flare (DORF) as measured from original soil surface to the top of the first tier, original root flare in centimeters. Location information see table 1…………………...66 Figure 9. Correlation graph of percent girdling root (%GR) and depth of original root flare (DORF): Percent girdling root (%GR) is a measurement of the total percent of the root collar that is constricted by girdling roots compared to the total circumference of the base of the trunk viii compared to the depth of original root flare (DORF) as measured from original soil surface to the top of the first tier, original root flare in centimeters. Location information is listed in Table 1...67 Figure 10. Correlation graph of average basal area growth rate (BAGR) and depth of original root flare (DORF): Basal area growth rate per year (BAGR) measures the average increase in basal area of the trunk 2 per year of growth. Cross sectional area of the trunk in cm , along with the determined tree age, was used to calculate average cross sectional growth rate per year. This was compared to the depth of original root flare (DORF) as measured from original soil surface to the top of the first tier, original root flare in centimeters. Location information is listed in Table 1………..67 Figure 11. Correlation graph of average basal area growth rate (BAGR) and depth of original root flare (DORF): Basal area growth rate per year (BAGR) measures the average increase in basal area of the trunk 2 per year of growth. Cross sectional area of the trunk in cm , along with the determined tree age, was used to calculate average cross sectional growth rate per year. This was compared to the depth of original root flare (DORF) as measured from original soil surface to the top of the first tier, original root flare in centimeters. Location information is listed in Table 1………………..68 Figure 12. Measuring depth of original root flare (DORF) at site AD: Demonstration of the technique used to measuring depth of original root flare………………….68 Figure 13. Iron rod data for BR1 and BR2: Soil oxygen levels and variations in soil strata were measured by driving iron rods into the ground, and later retrieval for visual inspection (Hodge & Knott, 1993). Three iron rods each made of high carbon steel from Alro steel (Alro Corp. Jackson, MI USA), 0.5 cm wide and 60 cm long, were driven into the ground around each of the test trees at each site in one of the four cardinal directions North, South, East, or West as determined by a compass, in random order. One rod was placed between 30 and 40 cm of the tree, the second at the half the distance from the trunk to the drip line of the tree, and the third at the drip line. Sites BR1 and BR2 had Iron rods installed between July 22nd and 28th 2008. The rods were left in the ground over the winter and removed the following spring starting on March 20th 2009. Each of the iron rods was located using maps and a metal detector. Rods where removed, cleaned with a soft bristle brush wiped with a shop towel, placed on a white back ground with an identification tag, and photographed for later visual inspection. Each of the rods was examined and a rust rating of no rust (0), mild rust (1) or severe rust (2) was assigned for every 2 cm of each rod…………………………………..69 Figure 14. Map of soil core transects BR1 and BR2: In 2009 soil sampling was done at sites BR1, and BR2. Transects were laid out across the two plots, with a core taken every ten feet across three transects……………………………………..70 Figure 15. Soil core auger: Picture of an AMS (AMS, Inc. American Falls, ID USA) Basic Soil Sampling Kit, cores were removed using a Sand Auger, 8.3 cm diameter, thread-on stainless steel Auger bucket, attached to a 122 cm thread-on extension, which was attached to an AMS thread-on cross handle. Coring was done to a depth of 91 cm, or until the corer reached an impediment that could not be cleared. Cores where extracted, removed, placed in line next to the extraction hole, photographed, and three soil samples taken, one form the top, middle, and bottom of the core……………………..70 ix Figure 16. Cores to determine top soil depth: Further soil cores were done in May 2013 to collect measurements of the depth of topsoil layer at sites BR1 and BR2 for comparison to Iron rod data from the shallowest 20cm. Using the original map of iron rod placement, each tree at the two BR sites had three cores taken with a 21 inch AMS® soil probe, in as close an approximation to the placement that the original iron rods were inserted in the ground. Soil samples were extracted, visually assessed for soil texture, and depth of top soil layer was measured in centimeters with a ruler. In this way a field average was collected for later comparison…………………………………………………………………….71 Figure 17. Leaf temperature/Scholander experiment: In 2012, a series of three tests were done at sites BR1 and BR2, comparing scorch and none scorch tree, and the possible relationship between leaf temperature and leaf pressure potential. Leaf temperature data was collected using an Extech® Instruments, (Extech® Instruments Nashua, NH U.S.A) InfaRed thermometer model 4252, IR gun (+or- 2% of reading), from ten different leaves in each of the six test trees. Of the six trees, three had a history of scorch, and three were non-scorched trees. Information on ambient temperature was collected by hanging a mercury thermometer in the under canopy of a nearby control tree, allowing it to acclimate for a minimum of 15 minutes, and taking a measurement before and after site work was initiated, along with cloud cover conditions. In addition, leaves were also collected from each of the test trees. For this experiment the leaves were not transported to the lab to obtain stomatal conductance data, rather the Scholander pressure chamber, Model 600, (PMS Instrument Company Albany, OR. USA) and the nitrogen tank were transported to the BR test site so that Scholander readings could be taken in the field………………………………………………………………………...72 Figure 18. Mauget branch injections: In 2009 a sub sample of trees at BR1, BR2, and FR were given injections of Manganese using the Mauget Inject-A-Min® (Mauget Arcadia, CA USA). Manganese micro-nutrient formulation 6 ml pressurized capsules containing, 1%N, 1%K20, 1.9% S, 0.13% Cu, 1.67% Fe, 1%Mn, 0.12% Mg, 1.54% Zn. These preliminary experiments were performed to see if scorch symptoms could be relieved in individual branches if injected at their bases…………………………………………73 Figure 19. Mauget trunk injections: There was another round of injections in 2010 to trees at sites BR1, BR2, FR, SW, and GR…...73 Figure 20. Mn. injections/soil sulfur pH experiments: Finally, a third round of injections was performed on nine trees in a sub-plot experiment at sites BR1, and BR2 in March of 2011. The experiment consisted of three control trees (Marked here as green circles with “C”), three trees which had micro-fine sulfur mixed with water applied to the area under their drip line (Marked here as yellow circles with ”S”), and three trees injected with the Mauget capsules (Marked here as pink circles with “M”). Each round of injections from 2009 - 2011 was performed with either photos taken of any changes to the foliage, and or leaf tissue was collected for nutrient analysis. In some cases both were done before and after the injections for comparison. Micro-fine sulfur application rates were calculated based on soil pH for each tree and the area under each trees drip line…………………………………………………………………………………………...……74 Figure 21. Soil sulphur injection: Micro-fine sulfur was applied in a liquid form using GreenGarde® (GreenGarde, Bedford, PA. USA). Heavy-duty root feeder with a flow meter was used to inject the liquid directly into the soil at a uniform depth of 25 cm………………………………………………………………….75 x