The smell of freshly cut grass may stir memories of baseball parks, cookouts or lazy summer afternoons in the suburbs, but what we perceive as a sweet aroma is actually the plant equivalent of a distress call, one that the grass releases to signal that the lawn is under attack.

The same thing happens frequently in vegetation all around us, but it goes unnoticed because humans normally don't have the ability to smell or see the special compounds called green leaf volatiles that other plant species emit when they are damaged by pests or disease.

"Plants have a defense mechanism in which they release unique chemicals as means of communicating with other plants," said University of Georgia researcher Ramaraja Ramasamy. "And the signature is very specific to the type of stress that is experienced by the plants."

Ramasamy, an assistant professor in the College of Engineering, is currently developing a chemical sensor to detect these odorless, invisible volatiles that foretell plant distress well before they show signs of disease or trauma.

The sensor has a variety of potential applications, but he hopes his work will have its greatest impact on farms and food storage facilities.

Crop losses due to plant pests and pathogens cost American farmers an estimated $33 billion dollars annually, according to the U.S. Department of Agriculture, and producers spend millions of dollars spraying pesticides, herbicides and fungicides on their fields to keep yields as high as possible.

Rather than spray entire fields with expensive chemicals as a preventive measure, Ramasamy hopes that farmers could rely on sensors that identify specific sectors of a field that are under stress.