HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Hammons, D. L. Articles by Potter, D. A. PubMed Articles by Hammons, D. L. Articles by Potter, D. A. Agricola Articles by Hammons, D. L. Articles by Potter, D. A.

Japanese Beetle Defoliation Reduces Primary Bud Cold Hardiness during Vineyard Establishment

¹ Department of Entomology, S-225 Agriculture Science Bldg. N., ² Department of Horticulture, N-318 Agricultural Science Bldg. N., University of Kentucky, Lexington, KY 40546; present address: Department of Viticulture and Enology, California State University, Fresno, CA 93740.

Acknowledgments: This work was partially funded by the New Crop Opportunities Center at the University of Kentucky through a USDA Special Grant and by a USDA SARE Graduate Student Grant to DLH. This is paper 09-08-046 of the Kentucky Agricultural Experiment Station.

The authors thank C. Brady, J. Condra, B. O’Daniel, C. Redmond, D. Slone, and P. Wilson for technical assistance and R. Bessin for statistical guidance.

^* Corresponding author (email: dapotter{at}uky.edu; fax: 859 323-1120)

Insect defoliation could reduce winter hardiness of young grapevines, but such effects have not previously been quantified for field-grown vines. The impact of Japanese beetle (JB) defoliation on midwinter primary bud cold hardiness of Norton, Chambourcin, and Cabernet Sauvignon grapevines was measured during the first two years of vineyard establishment. Effect on shoot length and periderm browning by late autumn was also evaluated for first-year vines. Three treatments were used to manipulate levels of defoliation: carbaryl applied either every 7 or every 14 days during the JB flight period (mid-June to mid-August) or no insecticide spray. Cuttings from dormant canes were subjected to a controlled freezing stress each February, and the temperature causing 50% lethal injury (LT₅₀) to primary buds was compared among cultivars and treatments. All three cultivars sustained similar levels of JB defoliation, which ranged from light (3 to 8%), to moderate (13 to 26%), to severe (38 to 48%) under the 7-day, 14-day, and no-spray regimes, respectively. Norton and Chambourcin primary buds were more cold tolerant (i.e., had lower LT₅₀) than Cabernet Sauvignon in both years. Japanese beetle defoliation of nonsprayed vines significantly reduced cold hardiness of all cultivars in one or both winters. Notably, biweekly cover sprays were as effective as weekly sprays in mitigating the adverse impact of JB defoliation on vine cold hardiness. Defoliation also reduced shoot length of first-year vines, and may be associated with earlier termination of late-season vine growth. The previously undocumented potential for JB injury to reduce winter hardiness of young grapevines exacerbates its impact as a serious vineyard pest.

Key words: defoliation, grapevine, Popillia japonica, LT₅₀