![Color-infrared image of giant salvinia: Link to photo information](/is/graphics/photos/nov01/k9653-20i.jpg)
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Survey Giant Salvinia with Remote Sensing?
By Marcia Wood
May 6, 2002
Infestations of giant salvinia, one of the world's worst water weeds,
might be more easily detected using airborne color-infrared photography.
This fern, known to scientists as Salvinia molesta, forms dense
mats in ponds, lakes and reservoirs. The mats use up oxygen that fish,
insects and other aquatic dwellers require. They also clog irrigation
and electrical-generating systems and snarl swimming, boating and waterskiing.
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Can this fellow
help solve salvinia?
![Salvinia weevil: Link to story](/is/graphics/photos/nov01/k9654-2x.jpg)
News: 2001
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![Close up of salvinia mat: Link to photo information](/is/graphics/photos/nov01/k9651-7i.jpg)
Click image for caption and other photo
information.
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Color-infrared photography, taken from aircraft-mounted cameras, is
a fast and affordable way to find and monitor the notorious weed. That
is according to Agricultural Research
Service rangeland scientist James
H. Everitt. He is based at the ARS Kika
de la Garza Subtropical Agricultural Research Center in Weslaco,
Texas. With colleagues from the Texas
Parks and Wildlife Department, Everitt tests remote sensing techniques
to spot salvinia outbreaks.
In these experiments, Everitt has analyzed color-infrared photographs
of salvinia in several lakes and ponds near Liberty and Bridge City
in southeast Texas. Color- infrared photography has been used for decades
to differentiate among types of vegetation, based on the amount of light
that each reflects. But, Everitt and co- researchers are likely the
first in the world to use color-infrared photos successfully to observe
salvinia outbreaks.
Everitt is currently exploring the possibility of combining color-infrared
video--instead of photography--with global positioning and geographic
information system technologies. He says the updated package could enable
researchers and waterway managers to find giant salvinia outbreaks faster
than if they used ground surveys.
ARS is the U.S. Department of Agriculture's
chief scientific research agency.
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