In 1982-1983, naturally formed blight cankers, within a zone ranging from the ground to 183 cm on three grafted American chestnut trees, were inoculated with a mixture of four European (white), and six, pigmented hypovirulent strains of Cryphonectria parasitica. A total of 202 C. parasitica isolates were recovered from 49 cankers located outside of the inoculated zone. Ninety-five isolates (47%) were white and 107 (53%) were pigmented. Forty-eight vegetative compatibility groups were identified among 110 white isolates collected from this and previous studies. The ratio of VC groups to isolates tested (S/N), and Shannon diversity index were calculated to be 0.43 and 3.64 respectively. Of the 48 VC groups identified, 25 consisted of two or more isolates. These 25 groups were found to be vegetatively incompatible with all four of the original hypovirulent white inoculated strains, consisting of three VC groups, but were compatible with five of the 11 most common pigmented VC groups recovered from previous studies. These data provide evidence for spread of the original European hypoviruses (Cryphonectria hypovirus 1, CHV1) but not for spread of the original inoculated strains. Forty-five VC groups therefore represent the minimum number of "new" VC groups into which one or more of the original hypoviruses (CHV1) have spread. Single-spore colonies of the white isolates recovered from the 49 cankers were placed into four cultural morphology (CM) groups based on degree and pattern of pigmentation, and type of colony margin in culture. The two largest CM groups contained 37 (CM group 3) and 33 (CM group 1) isolates. Single-spore colonies from the original, white inoculated strain, EP-49, were classified to CM groups 3 and 1, while colonies of EP-51W were classified into CM group 1. The spatial pattern of white isolates within cankers was evaluated using a 7 x 7 lattice plot. Spatial pattern determination using the join-count statistics, described by Pielou, indicated that three of the four cankers containing white isolates had random patterns of white isolates. Vegetative compatibility tests of C. parasitica isolates in the two cankers sampled for spatial pattern indicated that the majority of both white and pigmented isolates in the cankers were within the same VC group for each canker. This was frequently the case even when pigmented and white isolates occurred in adjacent lattice cells. Isolates in each of the cankers identified to VC group had random patterns of the major VC groups (includes pigmented and white isolates). Using a double matrix statistical test, the spatial pattern of white VC groups among the 49 cankers was found to be aggregated (P=0.019), whereas the spatial pattern of white isolates was found to be random (P=0.325). The Lloyd's index of patchiness value for the pattern of white isolates in all cankers was 0.91. This value is just less than 1.0, which would indicate a random pattern. / Master of Science

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; containsvii, 73 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 66-68).

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains viii, 72 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 65-67).

Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. "December 4, 1998" Document formatted into pages; contains vii, 80 p. : ill. (some col., col. map) Vita. Includes abstract. Includes bibliographical references (p. 41-46).

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xv, 168 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 142-149).

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains viii, 91 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 67-69).

No description available.

No description available.

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