From the pages of the Mid-January 2001 edition of Farm Journal magazine.

The ability to take digital pictures of crop damage and to transmit that image to plant experts for analysis is changing how farmers deal with crop loss.

When a Florida green-bean grower had to decide whether to spray a fungicide, for example, both the environment and his wallet caught a break--thanks to digital imagery.

Larry Halsey, Jefferson County, Fla., Extension director, received the grower's damaged plants. His first diagnosis was a disease called alternaria. However, Halsey knew alternaria is often a secondary invader, usually the result of previous plant damage.

He quickly sent digital images of the plant leaves and digital microscopic images of the lesions to plant experts at the Institute of Food and Agricultural Sciences, University of Florida. He also mailed the biological sample to the clinic.

The next day, the clinic let Halsey know his hunch was right--the disease was alternaria. Plant pathologists could see from Halsey's images that frost had caused the original leaf damage.

Rapid diagnosis. The diagnosis was confirmed on the second day by tests on the plant sample. The farmer had already been told to delay spraying a fungicide.

"Often, the farmer will see the damage and spray," Halsey says.

Not in this case. Since the damage had been done by frost, the additional cost and labor of fungicide application would have been totally wasted.

This is but one of a growing number of cases of timely disease and insect identification by a new digital analysis system called Distance Diagnostic and Identification System (DDIS). The system began a few years ago as a low-cost digital-camera network that e-mailed images within the Florida Extension system.

Each county Extension office is equipped with digital cameras. At least two-thirds of the offices have microscopes that attach to the digital cameras. Cost for both the camera and the microscope is approximately $2,200.

Agents record details and field conditions, then choose which university specialists receive an alert that the samples have been submitted. Specialists then make recommendations to the submitting agent.

Halsey says Extension services have a 60% to 75% success rate of diagnosing insect or weed problems from digital images alone. Diseases are more difficult and rely on a high-quality microscopic image of the pathogen. Even then, successful diagnosis of disease is only about 15%. When successful, a diagnosis can be made in a day instead of the week or more required for mailing and diagnosis of plant samples.

"Something might look like a disease but is actually something else," Halsey says. "I can send the images to a pathologist, a physiologist and to the [plant] nutrition people. If I'm wrong sending it to one lab, I'm right sending it to another."

Other states are also developing programs to use digital images for disease diagnosis and insect identification. The University of Georgia has developed a Web-based program called Distance Diagnostic Through Digital Imaging, which Halsey says other states are adopting.

At the University of Missouri-Columbia, some Extension agents have been sending digital images for diagnosis through e-mail for about three years.

"With images from the field, we can get an idea of the plant's environment," says Barbara Corwin, director of the Extension Plant Diagnostic Clinic. "That can help us give suggestions of the types of samples they should send in."

Aiding diagnosis. Laura Kabrick, an assistant in Corwin's clinic, agrees that environmental factors that the submitter believed were minor or insignificant, such as recent construction and surrounding plants, can be helpful in diagnosis. "People send in yellow leaves, but they are often just a symptom of a bigger problem," she says.

Kabrick says the highest diagnostic success rates result from digital images when the disease is or has become a common problem. "Ninety percent of the time an experienced person can diagnose a common problem from the image," she says.