National Geographic : 1969 Jan
Remote Sensing: New Eyes to See the World graphs of citrus orchards damaged by brown scale, and potato patches suffering from late blight (page 50). Similarly, infrared can detect invasion of insects such as the southern pine beetle, which killed 40 percent of the pines in Honduras in 1963-64. And Robert C. Heller of the Forest Service's Remote Sensing Project in Berkeley, Califor nia, told me of another infrared technique that may help to identify sick trees. These usually run from 5° to 150 F. warmer than healthy trees, and therefore register differently on infrared scanners. Will these techniques work from orbit? Dr. Colwell is sure that they will, although they have not yet been tested in spacecraft. No one can measure the economic implica tions of remote sensing for world agriculture. But it is estimated that fire, insects, and dis ease cause from 13 to 20 billion dollars of ag ricultural damage yearly in the United States alone; clearly, some of that toll can be saved by early detection and remedial measures. And at a time when the global population explosion is adding more than a million new mouths to feed every week, while starvation threatens large parts of the world, any crop saving measures have prime importance. Dr. Arch Park of the U. S. Department of Agri culture estimates that every dollar spent on remote sensing can yield $5 in savings. I asked Professor Colwell if infrared could ENSINGLABORATORY, UNIVERSITYOF CALIFORNIAC) N.G.S. that obscures the lake shore but brings out roads and trails. In a two-color combination (middle), hardwoods appear yellow while groves of conifers form dark smudges. Rocks stand out in a red-blue composite (bottom). By using such false-color com binations, Dr. Colwell suggests, aerial surveyors could make comprehensive inventories of a region's crop, forest, and water resources.