Population dynamics and dispersal gradient of Aphelenchoides fragariae in the woody ornamental Lantana camera.

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Title: Population dynamics and dispersal gradient of Aphelenchoides fragariae in the woody ornamental Lantana camera.
Author: Kohl, Lisa Michelle
Advisors: D. Michael Benson, Committee Chair
Candace H. Haigler, Committee Member
Eric L. Davis, Committee Member
Abstract: Foliar nematodes (Aphelenchoides fragariae) infect ornamental crops in greenhouse and nursery production. The objectives of this research were to study A. fragariae population dynamics in a woody ornamental, Lantana camara, during the growing season and during overwintering in a commercial nursery, and to determine the dispersal gradient of A. fragariae in a nursery with overhead irrigation. In the 2006, 2007, and 2008 growing seasons symptomatic, asymptomatic, and defoliated leaf samples were taken throughout a study plot of 30 lantana plants (Lantana camara) infected with foliar nematodes at a commercial nursery in North Carolina. Air temperature, relative humidity, and rainfall data were recorded at the nursery. Over the growing season, nematode densities per gram of fresh weight leaf tissue were low in May and June, and then reached a peak in July, with 122 nematodes/g in July 2006, 406 nematodes/g in July 2007, and 180 nematodes/g in July 2008. Nematode densities decreased over the rest of the summer, except for October 2007 when a second peak occurred. Nematode densities in symptomatic leaves were positively correlated with daily high temperatures and daily low temperatures, while nematode density in asymptomatic leaves were positively correlated to daily low temperatures and relative humidity. Nematode densities in defoliated leaf samples were positively correlated to relative humidity, daily low temperatures, and daily high temperatures. Leaves were also collected during the 2006-7 and 2007-8 overwintering seasons, when the 30 lantana plants were moved to a polyhouse. During overwintering nematode counts remained low in the three different types of leaf tissue, but nematodes were still detected throughout the overwintering season. In 2007 and 2008 a dispersal gradient for foliar nematodes was examined during the summer at a research nursery by spacing healthy plants at a distance of 0 (touching), 30, or 100 cm from an A. fragariae-infected source plant. After 11 weeks in 2007, 100% of the plants at the 0 cm from the inoculum source were infected, while only 10% of the plants at the 30 cm distance and 5% of the plants at the 100 cm distance were infected. In 2008 100% of the plants at the 0 cm spacing became infected after 12 weeks, and 5% of the plants at the 30 cm spacing became infected. No plants at the 100 cm spacing became infected in 2008.
Date: 2008-12-01
Degree: MS
Discipline: Plant Pathology
URI: http://www.lib.ncsu.edu/resolver/1840.16/1457


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