<p>In 2016, chestnut oak (<em>Quercus prinus</em>) trees across southern Indiana began displaying symptoms of decline disease. In the years following, widespread patches of mortality appeared on slopes and along ridges, prompting the Indiana Department of Natural Resources (IDNR) to investigate. The IDNR noted the presence of <em>Phytophthora cinnamomi </em>on one diseased chestnut oak, leading to the initiation of this study. Our goals were to (1) determine if <em>P. cinnamomi </em>contributed to the widespread decline, (2) determine what site or stand variables were associated with higher rates decline, (3) examine the growth of declining trees prior to the onset of symptoms to determine if drought contributed to decline, and (4) use Forest Service Forest Inventory and Analysis (FIA) data to examine trends in regional chestnut oak mortality.</p> <p>From 2021-2022, we collected thirty fine root and soil samples from declining chestnut oak trees within Morgan-Monroe State Forest, Yellowwood State Forest, and the Hoosier National Forest. Throughout these forests, we established sampling plots within declining and healthy chestnut oak stands. In each plot we recorded site, stand, and tree level variables, then collected tree cores from two or three chestnut oak trees. Fine root samples were tested for the presence of <em>P. cinnamomi </em>at the Purdue Pathogen and Pest Diagnostic Laboratory (PPDL) in West Lafayette, Indiana.</p> <p>We used binomial linear regression to test for significant (α = 0.05) relationships between site and stand variables and decline, where a binary decline or no decline was used as the response variable. Both basal area increment (BAI) and ring width index (RWI) chronologies were built separately for healthy, declining, and dead chestnut oak trees. We used a paired t-test (α = 0.05) to test for significant differences in 10-year segments of BAI between the three chronologies. Finally, we used linear regression to test for significant (α = 0.05) effects of the standardized precipitation-evapotranspiration index (SPEI) in current and previous year growing seasons on RWI. Chestnut oak mortality volume across the eastern United States was calculated using the EVALIdator tool provided by USDA-FS FIA. Associations between chestnut oak mortality recorded by FIA and several climate and topographical variables were examined using a random forest classification.</p> <p>Out of thirty fine root samples, only one tested positive for the presence of <em>P. cinnamomi</em>, indicating that this decline was not associated with the pathogen. The analysis of site and stand variables revealed a greater chance of decline on east and northeastern facing slopes, with a slight increase in decline likelihood with increasing stand density. There was significantly lower BAI in dead and declining trees long before decline symptoms began, a pattern consistent with previous drought induced declines. We observed a significant relationship between RWI and SPEI in the early growing season (June and 3-month June SPEI) and throughout almost all of the prior year’s growing season (May, June, 3-month June, 3-month July, and 3-month August SPEI). Chestnut oak mortality volume across the eastern US steadily increased from 2006-2020, indicating a region-wide increase in mortality. Our random forest classification indicated the importance of increased precipitation and precipitation timing on chestnut oak mortality.</p> <p>Chestnut oak decline observed in southern Indiana was induced by a series of droughts in 2005, 2007, and 2012. The greater early life BAI of chestnut oak which were impacted by decline revealed that individuals which likely prioritized stem growth over root growth were predisposed to decline and mortality from these droughts. This prioritization could be brought on by genetic differences, favoring rapid height growth in developing even-aged stands, or by an abundance of moisture availability. Our FIA analysis of mortality revealed increased mortality volume across many states from 2006-2020, and that chestnut oak mortality may be related to greater precipitation compared to historic levels. Considering these results, we suspect that chestnut oak which have recently died or are currently declining are likely individuals which lack the root system to endure repeated drought.</p>

No description available.

Sixty-two natural cankers on branches and main stems of three 16-year-old grafted American chestnut trees at the Lesesne State Forest were sampled for Cryphonectria parasitica. Cankers were sampled in 1996 and 1997 at various distances from the main stem zone on the grafts (ground to 183 cm) that was inoculated in 1982 and 1983 with a mixture of dsRNA-containing white and pigmented hypovirulent strains. Grafted trees exhibited a high level of blight control, and all bark cores extracted from cankers on the grafted trees showed superficial necrosis. Bark cores extracted from these cankers yielded 156 isolates of C. parasitica. Fifty-three of these isolates were white, and 103 were pigmented. The farthest canker containing a white isolate was located 564 cm from the zone inoculated with hypovirulent strains (H-inoculated zone). The number of white isolates recovered per canker on the grafted trees near the H-inoculated zone (< 0.5 maximum sampling distance) was significantly greater (P=0.0039) than the number of white isolates recovered per canker on the grafted trees far from the H-inoculated zone (>0.5 maximum sampling distance). Lloyd's index of patchiness value for the frequency of white isolates in cankers was 1.36, indicating that white isolates were slightly aggregated in cankers. White isolates of C. parasitica were found in two of seven artificially established cankers 5 months after inoculation with a pigmented virulent strain (WK). Thirteen of 14 pigmented isolates collected from these cankers after 5 months were compatible with WK in vegetative compatibility (VC) tests. Eight of 25 white isolates recovered 5, 11, and 50 months after WK inoculation converted the pigmented WK strain to the white hypovirulent phenotype in vitro. Sixty-five pigmented isolates collected from natural cankers were paired in VC assays, revealing 28 VC groups. All 11 white isolates of C. parasitica assayed contained a 12.7 kb dsRNA in high concentrations. None of 48 pigmented isolates assayed contained dsRNA. All white isolates tested in virulence trials on American chestnut stems in a forest clearcut were hypovirulent, based on low canker severity indices. Little or no dissemination of white strains to cankers on the American chestnut stump sprout clusters, which surround the grafted trees, was found. In the future, to maximize spread of white hypovirulent strains on American chestnut trees, it may be beneficial to re-inoculate trees with hypovirulent strains farther up the main stem after substantial tree growth has occurred. / Master of Science

Thesis (M.S.)--Ohio University, March, 2004. / Includes bibliographical references (p. 24-30).

Thesis (M.S.)--Miami University, Dept. of Botany, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], v, 38 p. : ill. Includes bibliographical references (p. 35-38).

Thesis (M.S.)--Ohio University, March, 2004. / Title from PDF t.p. Includes bibliographical references (p. 24-30)

No description available.

Results of inoculations of grafts, seedlings, excised stems, and intact trees of large, surviving American chestnut indicated that some have heritable blight resistance. Some degree of resistance in American chestnut possibly would assist spread of hypovirulence (H) factors. The pathogenicity of the H isolate but not the V (virulent) isolate appeared to influence the size and sporulating characteristics of biocontrolled H+V cankers. The histopathology of canker development on blight-resistant Chinese and blight-resistant and blight-susceptible American chestnut was examined after inoculation with V and H E-parasitica. Rapid formation and continual growth of mycelial fans distinguished chestnut blight cankers incited by V E-parasitica from those incited by H E-parasitica, and distinguished cankers on susceptible chestnut from cankers on resistant chestnut. Differences among such cankers in wound periderm and other pathological alterations of bark and wood anatomy probably were results of differences in rates of fan formation and growth. Wound periderm formation began at the deepest point of a wound or canker and progressed outward to the bark surface. Superficial cankers arose in resistant trees or with hypovirulent fungus when slow-forming mycelial fans expanded through areas where wound periderm had not formed. Rapid epidemics of chestnut blight occur in recently clearcut areas but not in areas with large trees of species other than American chestnut, most probably because chestnut sprouts released after cutting become larger than they do when overtopped by large forest trees. The size of chestnut sprouts appeared to influence the rate of blight progress by setting a maximum limit on canker size and thus canker sporulation. It may be possible to foster spread of H factors in the Appalachians if blight epidemics in clearcuts can be prolonged. This might be done by restricting inoculum production. Cutting and removing some blighted sprouts, cutting some large unblighted sprouts, or increasing blight resistance in the chestnut population are three potential means of restricting inoculum production. / Ph. D.

The present study was aimed to find out if there is any symbioses between C.australe roots and mycorrhizal fungi. This research also aimed to investigate the effect of Arbuscular mycorrhizal fungi on the growth of C.australe and the yield of alkaloid castanospermine. The rhizosphere soil and roots of C.australe from various sites in Sydney were collected. Roots were stained with vital and non-vital stains for assessment of mycorrhizal infection. The result indicated that AM fungi symbiotic associations with the roots of C.australe, producing arbuscules and vesicles in the root cortices. By wet sieving and decanting of rhizosphere soil, spores and sporocarps of AM fungi, were recovered. The spores mainly belonged to the genus Glomus. A correlation study was conducted to determine the relationship between the AM infection percentage in the roots and the Castanospermine amount in the leaves and seeds of the field grown trees. The results showed that there is a positive relationship between the castanospermine amount in the seeds and AM infection percentages in the roots. The effect of phosphorus on the yield of castanospermine was also investigated. The results indicated that phosphorus do enhance castanospermine at certain levels, but a further increase in phosphorus application resulted in reduced AM infection. It was found that AM has a great effect on the growth and production of C.australe and biosynthesis of castanospermine. / Master of Science

In anticipation of widespread planting of putatively blight-resistant hybrid chestnuts (Castanea spp.), it is critical to understand the silvics and competitive ability of the species. This dissertation examines preliminary growth and survival of several species and genetic crosses of chestnut grown as 1-0 high-quality nursery seedlings and planted in two study sites: Southeastern Kentucky (Daniel Boone National Forest; chapter 2), and Northeastern Connecticut (Yale-Myers Forest; chapter 4). The effects of three silvicultural treatments on the Daniel Boone National Forest (DBNF), and four silvicultural treatments on the Yale-Myers Forest (YM) were evaluated. Furthermore, the effect of initial seedling size on seedling performance was tested. In both studies, seedlings grew largest in height and root collar diameter in silvicultural treatments with the most available light. High mortality at the DBNF planting was caused by Phytophthora cinnamomi, ink disease, and high mortality at the YM planting was caused by repeated deer, Odocoileus virginianus, browsing and competition from hay-scented fern, Dennstaedtia punctilobula. Additionally, seedlings at the DBNF study were repeatedly defoliated by Craesus castaneae, chestnut sawfly, during the first growing season (chapter 3). Seedlings with larger root collar diameters at planting demonstrated greater survival and growth in the DBNF study while seedlings larger in height and RCD added less growth and were more likely to die in the YM study, likely due to the high deer population and dense understory competition. These results indicate that silvicultural treatments that create high-light environments are ideal for chestnut, however the species can establish successfully under a variety of light conditions, from low light [10% photosynthetically active radiation (PAR)] to high light (65% PAR). Ink disease will present a formidable obstacle to chestnut reintroduction efforts in the south, while northern efforts will be challenged by deer browsing due to overpopulated deer herds.