Project Number: 5358-21000-037-44
Project Type: Reimbursable

Start Date: Oct 01, 2010
End Date: Aug 31, 2013

Objective:
1) Identify the distribution of GLRaV species throughout the season to determine if the observed increased incidence and damage results from changes in the GLRaV complex, combinations of GLRaV species, or new relationships between the pathogen(s) and its insect vectors. 2) To determine seasonal changes in the occurrence of both pathogen and vector in order to provide a better understanding of GLRaV epidemiology and leafroll incidence. 3) To investigate the impact of conventional and sustainable mealybug controls on the levels of disease incidence. 4) To develop an outreach program on GLRaVs and mealybugs.

Approach:
Determine the etiological agent(s) of leafroll disease in vineyards where it is of critical economic importance and where it is considered of minor importance, allowing for comparison of symptoms and the development of reliable and sensitive diagnostic tools targeted to the pathogen. Furthermore, establishing rates of leafroll disease incidence and distribution of GLRaV types throughout the sampled regions will provide a baseline for future efforts in controlling the spread of these pathogens. Combined with the vineyard profile data collected, analysis of this data with tools such as ArcGIS and statistical correlations will also provide initial information on (a) the distribution and abundance of the insect vectors associated with GLRaV, and (b) relationships between mealybug species and different GLRaV types. Survey vineyard blocks in Napa and Sonoma Counties for the presence of both vector and pathogen. Use natural populations to investigate their association and link their seasonal population densities to leafroll incidence. Manipulate mealybugs on infested plants to determine acquisition efficiencies at different times of the season and when the vector is feeding on different plant parts. Compare conventional vs. sustainable controls for vine mealybug and record changes in leafroll incidence. Specialty Crops Research Initiative. Documents Reimbursablew ith UC Berkeley. Log 39181.