Evaluation of grape germplasm for resistance to Pierce's disease and glassy-winged sharpshooter

Elvis E. Clarke, Zhong Bo Ren, Jiang Lu

Abstract


Field grown Vitis plants consisted of 45 cultivars/accessions representing the European, Asian and American species and hybrids were evaluated for resistance/tolerance to Pierce's disease (PD) and the glassy-winged sharpshooter (GWSS), which is the major vector responsible for the transmission of the bacteria (Xylella fastidiosa Well) that cause the disease. Evaluation for resistance to PD was conducted biweekly by rating the disease on a scale of 0-5, where 0 = no symptoms, 1= minor symptoms up to 10% of leaves with marginal necrosis (MN), 2 = 11-30% of leaves with MN, 3 = 31-50% of leaves with MN, 4 = 51-75% of leaves with MN and 5 represented over 76% of leaves with MN or a dead vine. Evaluation for GWSS resistance was based on field observation of GWSS counts on individual vines. Results indicated that the Europe- an and some North American species were very susceptible to PD, while the Vitis species native to the Gulf Coastal Plains of the United States, such as V. rotundifolia and V. shuttleworthii were resistant to PD. The Florida hybrid bunch grapes, such as 'Blanc du Bois', 'Stover' and 'Conquistador', showed some tolerance. The Asian species appeared to be susceptible to PD. There is a tendency that PD susceptible varieties/accessions received more visits of GWSS although the correlation between disease severity and GWSS counts was inconsistent for some accessions.

Keywords


xylella fastidiosa; vitis germplasm

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283