Project Scientists: Roy Armstrong, Cindy Bell, Liane Guild, Christine Hlavka, Lee Johnson, Joan Salute, Vern Vanderbilt
California vineyards produce 76% of all wine consumed in the United States, and are the basis of a $9 billion per year industry. Grape phylloxera, a root-louse, currently threatens California vineyards by destroying vines which are own-rooted or are grafted onto susceptible rootstocks. The only known remedy for the infestation is to replant vineyards on phylloxera-resistant rootstock, a process which may eventually cost the industry one billion dollars. NASA Ames' Earth System Science Division is collaborating with industry and university partners to develop and transfer the use of remote sensing and geographic information system (GIS) technology to vineyard managers in the Napa Valley. The technology is intended to provide timely information on the extent of infestation and factors affecting its spread.
In the project's initial year (1993), several data sets were collected during the May-October growing season. A laboratory instrument was used to detect and monitor leaf spectral (color) differences among leaves from uninfested, mildly infested, and severely infested vines throughout the season (Figure 1) . Aircraft spectral measurements of vineyards were made with the Compact Airborne Spectrographic Imager (CASI) in July 1993. The CASI data were shown to be sensitive to leaf area of the vines, which was in turn related to degree of infestation (Figure 2). Information on soils, irrigation, cultivation practices, and locations of past infestation recorded from historical air photos (Figure 3) were compiled into a GIS to study the extent and rate of infestation. Remotely sensed data will be incorporated into the GIS to show areas of active infestation and to predict future spread. Finally, satellite data for the entire Napa Valley (Figure 4) are being analyzed to produce land use maps showing the decrease in grape acreage due to infestation and urbanization over the last decade.
Initial results indicate that heavily infested areas are clearly identified in the airborne imagery. The remotely sensed data appear to be useful for detection of mild (pre-visual) infestation as well, while providing valuable information regarding irrigation and other crop management practices in uninfested fields. Early phylloxera detection will provide the vineyard manager more time in which to develop informed and cost-effective replanting decisions. Project results will be made available to other interested grape growers, commercial remote sensing product vendors, and the broader agricultural community.
COLLABORATORS: Robert Mondavi Winery, University of California Cooperative Extension, California State University at Chico, University of California at Davis.
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