Thesis Title

The Effects of Grapevine Leafroll-Associated Virus-3 and Grapevine Fleck Virus Infection on St. Vincent and Vidal Blanc Grapevines

Date of Graduation

Spring 2000

Degree

Master of Science in Plant Science

Department

Biology

Committee Chair

Martin Kaps

Subject Categories

Plant Sciences

Abstract

This study investigated the effects of grapevine leafroll-associated virus-3 (GLRaV-3) and grapevine fleck virus (GFkV) infections on St. Vincent and Vidal blanc grapevines. The objectives were to determine virus distribution with vines, and bud cold hardiness in both virus infected and not infected vines. Enzyme-linked immunosorbent assay (ELISA) was used to determine virus infection. Ten canes were sampled along the cordon from six vines of each cultivar and tested for virus. Only one St. Vincent vine had both positive and negative results for GLRaV-3 along the cordon. Additional testing showed one root, two trunk, and three of four cordon samples positive for GLRaV-3. This implied that an uneven distribution of virus occurred in the vine, and that the virus spread froam basal to distal parts. Bud cold hardiness was determined using differential thermal analysis (DTA). Three canes were sampled along the cordon from sixteen vines of each cultivar and virus condition at three sampling periods during the fall/winter of 1999/2000. No differences in bud cold hardiness between not infected and GLRaV-3 infected St. Vincent vines occurred. Significant differences in bud cold hardiness were found between the virus conditions of Vidal blanc in two of three sample periods. Virus infected vines had greater bud injury with decreasing temperature than not infected vines. Four canes were sampled along the cordon from eight vines of each cultivar and virus condition in November 1999. Two canes were upright and two were downward, corresponding to sun exposed and shaded conditions the previous growing season. All buds on canes were subjected to DTA. Significant differences in bud cold hardiness were found between exposed and shaded canes. Buds from shaded canes had a greater injury with decreasing temperature. A cumulative effect of shaded canes and virus infection increasing bud injury occurred for St. Vincent.

Copyright

© Marc A. Fortenberry

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