A digital camera and a laptop computer could help cotton producers make on-the-spot replant decisions, according to Missouri Extension cotton specialist Bobby Phipps.
The use of the new technology “is still in the preliminary stages,” said Phipps. “But it sure holds some promise.” The project is being funded by Cotton Incorporated and is now in its third year.
Phipps first saw the technique two years ago when Barry Bean (a cotton buyer from Peach Orchard, Mo.) showed him photographs of seedling cotton in his father's cotton field.
“He shot the roll using infrared film and an orange filter,” Phipps said. “That turned the green leaves of the cotton seedlings bright red. The red represented living tissue since living chlorophyll reflects more infrared than a dead plant.”
Phipps wondered if the images could help a grower with his replant decision, which often is a struggle between pessimism and hope. “When a grower calls you out to a field to get advice on replanting, he usually says, ‘My crop's half dead.’ But the point is that it's half alive. I've seen times when they replanted and had more plants than they needed to begin with. They don't see the live tissue. They see what died.”
The drawback to using infrared film is it can take up to two weeks to process, and the replant decision needs to be made more quickly than that. And a grower or consultant would need a lot of expertise to develop the temperature-sensitive infrared film by himself.
To get around the time-delay problem, Phipps decided to try a digital camera and use a software program on the camera to manipulate the color ranges “to match what we're seeing in the photos that Barry had made.”
“We got the result we were looking for,” Phipps said. “We changed the hue and saturation and rotated every color on the color wheel 220 degrees. That makes the greens become red. We save the picture and saturate it one more time. That makes the reds in the picture almost iridescent.”
Dead tissue, meanwhile, is muted and blends into the background as a gray or blue.
Phipps is also using a computer software program called Adobe PhotoShop to take the technology to another level of sophistication. “We started taking photos each week. When plants would die, we would look back at earlier photos to see if we could predict which plants were going to die.”
Another benefit of the process is determining the presence and health of weeds, according to Phipps. “When you start saturating the images, all of a sudden there are weeds all over the place. I had a block in Andy Kendig's weed trials that had an awesome weed kill on a Roundup Ready plot. But when you put the red on it, quite a few weeds were poking through. (Kendig is a weed scientist with the Delta Center.)
“A lot of times, the grower's eyes are diverted to the dead weeds,” Phipps explained. “But they don't see those little green ones peeking through.” Phipps would also like to use the images to “predict” weed death as he is doing with cotton plants.
The process of taking the photo (which Phipps does with a $300 digital camera), downloading it into the laptop and manipulating the image via the software program takes only about two minutes, he says. “But the grower still makes the actual replant decision.
“We have to study it a little more and learn how to interpret it,” says Phipps. But he plans to use the technology this spring in southeast Missouri, where as much as 50 percent of the crop planted by May 23 may have to be replanted.
Phipps believes that even more uses could be developed for the technology. “It's like having a new set of eyes. There are things out there that the camera sees that we can't.”
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