Under the direction of remote sensing researcher Lee Johnson,
scientists at NASA Ames Research Center became involved with the Mondavi
winery to find ways to predict the devastation of the crops. They set
up a series of trials wherein they used multi-spectral digital cameras
mounted on aircraft to detect the insects by measuring the density of
foliage across the vineyard. The studies helped the vineyards monitor
the spread of the insects so that they would know precisely when and
where they had to pull the existing grapevines and replant with
phylloxera resistant vines. In the midst of this project, those
researchers involved realized that this same technology could be used to
separate vines of varying vigor.
In these phylloxera experiments, we saw with the
multi-spectral imaging data that the amount of foliage on the vines is
directly related to their stress levels, says Johnson. In
phylloxera infested plants, a lack of foliageeither fewer leaves
or smaller leavesusually means the plant has become stressed by
the insects and is dying. The researchers reasoned that differing
amounts of foliage in crops that are not infested may be a good
indicator of vine vigor. Specifically, more vigorous plants will have
more foliage.
NASA and the Mondavi winery teamed up again in an experiment named
CRUSH (Canopy Remote sensing for Uniformly Segmented Harvest) to test
whether remote sensing could delineate the plants by their vigor and
ultimately by the quality and characteristics of the grapes the vines
produce. Johnson explains that the multi-spectral imager they used is
essentially a very precise digital camera. Unlike a hand-held camera
with film, this imager has several types of digital photoreceptors on it
that record very specific wavelengths (colors) of light. The ADAR
System 5500 the Ames scientists employed was developed with the
assistance of NASAs Commercial Remote Sensing Program and has four
different sensors. One detects only the blue light, one detects only
the green light, one the red light, and one the near-infrared light.
The data the sensors receive are fed into a computer where images can be
produced of each band or combinations of the bands (Johnson et al.,
1998). |
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Propeller driven aircraft similar to this one, operated by
Air Flight Services, carry the ADAR 5500 instrument that imaged the Robert Mondavi vineyard. After the NASA and Robert Mondavi Winery
scientists published their results, several additional California wineries used airborne remote sensing
to gather information about their vineyards. (Image copyright Positive
Systems, Inc, Whitefish, MT)
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For the CRUSH project, the scientists mounted this imager on a prop
airplane, which was then flown 15,000 feet above the vineyard. To
determine the thickness of foliage across a vineyard, they trained the
imager on the amount and colors of sunlight reflected off the leaves
(Johnson et al., 1998). As can be seen through a prism, many different
wavelengths make up the spectrum of sunlight. When sunlight strikes
objects, certain parts of this spectrum are absorbed and other parts are
reflected, and some heat is emitted. In plant leaves, chlorophyll
absorbs red light and other visible wavelengths from the sun for use in
photosynthesis. The cell structure of the leaves on the other hand
reflects near infrared light. The more foliage a plant has, the more
these types of light are affected.
Since the imager measures the intensity of infrared and red light
coming off the vineyard, the scientists simply gathered the data the
instrument recorded on its flight and compared the intensity of the two
types of light across the vineyard. In general, where the difference
between infrared and red light was at a high value, then the vines had
more foliage and were probably more vigorous. Where the imager recorded
low values of this difference, the vegetation was less dense and the
vines were probably less vigorous. All of these imaging data were then
fed into a Geographic Information System, computer software that
essentially matches up the raw images with the landmarks and topography
on the ground. The result was a complete map of the vineyard showing
general areas where the vines were vigorous, and areas where the vines
were stressed.
The remote sensing gave us a good rough outline of where the
high, medium and low-vigor plants were, says Johnson. Technicians
at the winery then went around to these areas and tasted the grapes and
ran a number of chemical and water tests to see if the aircraft
measurements were correct. After some trial and error, they were able
to get a full picture of grapevine vigor across many acres of the
Mondavi winery. |
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Healthy vegetation
strongly reflects infrared light, but absorbs most green light. The false color image at left
is made up of the near infrared, red, and green bands from the ADAR 5500 remote
sensing system in the red, green, and blue channels of the image. Vigorous vegetation, such as
the stand of trees at upper right, are bright red. Stressed vegetation, like the vines
running diagonally through the lower vineyard, is bluish. Roads, water, and buildings are bright
white or dark blue.
The patterns of healthy and stressed vines are enhanced by comparing the near infrared
and visible light data (right). Vigorous vines are colored green, and progressively stressed vines
go from yellow to brown. Using these data, the vineyard managers can subdivide the vineyard into
regions of similarly healthy vines. (Image courtesy CRUSH project, NASA Ames Research Center) |
Its amazing to see how small a change in slope, for
instance can affect the quality of the grapes. We found that an increase
of a few inches in elevation on a hillside will make a difference,"
says Bosch. Over the past two years, the winery has begun to
micromanage the vineyard based on these subtle differences in vigor.
Given the vigor of the vine, Bosch explains they can change the amount
of shoots grown by first pruning for the correct number in the fall and
then increasing or decreasing the amount of irrigation water the vine
receives as it grows. Though it still takes some time to get results,
every acre of the vineyard that they can transform into reserve wine
quality grapes increases their revenue by $800 per year. Of course in
some areas theyve found that the vigor is the same throughout and
there is not much they can do.
Beyond providing the wineries with a bigger profit, the remote
sensing images have educated the technicians in how to manage a
vineyard. Seeing all of it at once gives us more experience and
the ability to recognize the patterns fairly quickly, says Bosch.
Only after a few years of using the remote sensing devices, he boasts he
is getting to the point where he can spot the variation on his own
without the imagery. In the fall, he can now clearly see the order in
which the leaves turn. Within the span of a few years, theyve
essentially been able to do what took the French decades to accomplish.
This is a real revolution in how we are able to manage our
vineyards, says Bosch.
Successful Tests Lead to Ongoing Research
Johnson says that the process they developed has already been
commercialized. Several remote sensing companies that work with Ames are
offering remote sensing for any vineyard willing to pay the price, and a
number of the wealthy larger wineries in the valley are employing the
technology. While all this refinement has the potential of being of
great benefit to wineries and wine connoisseur alike, their experiments
with the Mondavi winery are far from over.
Ultimately Johnson would like to know how vigorous vines on a patch
of land will be before they even plant the first seedling. His team is
working with several models developed jointly by scientists at NASA and
the University of Montana that may be able to do just that. Given the
topography and soil type of a patch of land, these models should
simulate how various crops will grow on uncultivated land. In this
way wineries could design a vineyard based on plant vigor from the
start, says Johnson. Experiments like the ones they performed at
the Mondavi winery allow the scientists to refine the model. By first
testing the model on regions that are already planted, they can get
estimates on how the model works and then adjust it to work on areas
without plants.
In the long run, the goal of the Ames team is not only to improve the
quality of wine in California, but also to gain a better understanding
of how to use remote sensing systems and irrigation methods to deal with
crop stress. Farmers who raise soybean and corn crops do not want their
plants to be stressed at all. By understanding what causes stress in
wineries, future agriculturists may be able to look at any crop and tell
farmers the best way to irrigate and farm using the least possible
resources. The study is a nice example of a NASA-funded science
project that has scientific merit as well as economic benefits,
says Johnson.
- References
- Johnson, L., B. Lobitz, D. Bosch, S. Wiechers, D. Williams,
and P. Skinner, 1998: Of Pixels and Paletes: Can Geospacial Technologies
Help Produce a Better Wine, Proceedings 1st International
Conference on Geospacial Information in Agriculture and Forestry,
1-3 June, pp. II-469- II-475.
It's All in the Grapes |
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This Robert Mondavi Vineyard manager is using the vineyard image and
a personal GPS to navigate and prepare the field for harvest. He
is sectioning off different parts of the field,
based on vigor, with flagging tape. Grapes from different sections were
fermented separately. Here, highest quality reserve wine was produced
from low vigor areas. (Image courtesy CRUSH project, NASA Ames Research Center)
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