Cindy Bell’s research while affiliated with California State University, Monterey Bay and other places

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Publications (1)


Figure 1. Example of leaf and soil spectra. The REIP is the point of maximum slope in the spectrum of a leaf. A healthy leaf has a broader spectral absorption in the red (680 nm) and REIP occurs at a longer wavelength, as compared to a stressed leaf. 
Figure 3. Block I classified NDVI 1993 and 1994 images, where the lowest NDVI values are shown in black and the highest values in white, also shown in white are the boundaries of the block and plots within the block. A large patch of low canopy cover vines can be seen in the lower right, contrasting with the trees at the extreme right edge of the 1993 image. Multiple patches of low canopy cover vines can be seen in the 1994 image. "Rainbow" colored images were used during image analysis and initial products were colored by vigor level: brown for little or no vegetation, yellow for some vegetation, and green for high vegetation cover.
Figure 4. NDVI class histograms for block I. Class 0 percentages represent pixels below the bare soil threshold. Only ten of the twelve classes used for the ranch were present in block I. 
Table 4 . Mean Red Edge Inflection Point (REIP) wavelengths from 1993 oblique CASI estimated from five (680 -788 nm) channels
Figure 5. Block I pruning weight per plot for both 1993 and 1994 correlated well with the per- 2 2 plot mean Normalized Difference Vegetation Index class number. In 1993, R = 0.60; in 1994, R 

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Grapevine Remote Sensing Analysis of Phylloxera Early Stress (GRAPES): Remote Sensing Analysis Summary
  • Article
  • Full-text available

January 1998

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490 Reads

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13 Citations

Brad Lobitz

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Lee Johnson

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Chris Hlavka

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Cindy Bell

High spatial resolution airborne imagery was acquired in California's Napa Valley in 1993 and 1994 as part of the Grapevine Remote sensing Analysis of Phylloxera Early Stress (GRAPES) project. Investigators from NASA, the University of California, the California State University, and Robert Mondavi Winery examined the application of airborne digital imaging technology to vineyard management, with emphasis on detecting the phylloxera infestation in California vineyards. Because the root louse causes vine stress that leads to grapevine death in three to five years, the infested areas must be replanted with resistant rootstock. Early detection of infestation and changing cultural practices can compensate for vine damage. Vineyard managers need improved information to decide where and when to replant fields or sections of fields to minimize crop financial losses. Annual relative changes in leaf area due to phylloxera infestation were determined by using information obtained from computing Normalized Difference Vegetation Index (NDVI) images. Two other methods of monitoring vineyards through imagery were also investigated: optical sensing of the Red Edge Inflection Point (REIP), and thermal sensing. These did not convey the stress patterns as well as the NDVI imagery and require specialized sensor configurations. NDVI-derived products are recommended for monitoring phylloxera infestations.

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Citations (1)


... Because of its extended use and suitability for leaf area (source) estimation [37], NDVI was picked as the vegetation index to be used and estimated from R and NIR bands [38]. For the post-veraison period, any image date within the date range was considered acceptable, with preference for unfilled or fused data. ...

Reference:

Vine yield estimation from block to regional scale employing remote sensing, weather, and management data. Information Processing in Agriculture
Grapevine Remote Sensing Analysis of Phylloxera Early Stress (GRAPES): Remote Sensing Analysis Summary