A smarter way to spray

09/01/2006 02:00:00 AM

Focused sprays help cut pesticide drift and ground and water contamination as concern grows over farm neighbors and waterway buffer zones.

"The first step in reducing drift is targeting the tree," Niederholzer says.

Keeping pesticides on target also aids worker safety, he says.

Building a better targeted sprayer
Researchers are focusing on ways to make targeted sprayers even more efficient. Current sensing technology determines the presence or absence of a tree canopy and opens and closes spray nozzles accordingly. An improvement over continuous spraying, it's still a rough measure, says Masoud Salyani, professor of agricultural and biological engineering at the University of

Florida's Citrus Research and Education Center in Lake Alfred.

Because orchards and groves contain a wide range of canopy structures, customizing spray patterns to individual trees would create still more gains, Salyani says.

Ultrasonic signals fan out with distance, reducing precision at the far edges. Laser sensors emit nonspreading signals that travel faster and generate plenty of data for more precise calculations of tree characteristics, he says.

Salyani and his colleagues are developing a laser-based system that will detect not only canopy presence and size, but also density. A thick, tight canopy intercepts more spray material than a loose or dead canopy, with noticeable differences in drift.

Cordero says Durand-Wayland is switching to tracking sprayer locations with global positioning system units, which could lead to pinpointing spray treatments for specific problems to individual trees. The company's SmartSpray equipment currently uses radar tracking.

Other improvements in development would alter application rates for canopy density or growth stage during the season, he says.

Targeting technology does have limitations, particularly speed, Salyani says. The faster the sprayer runs through the block, the greater the savings, but driving too fast can create spotty coverage from outrunning sensor processing and bouncing over uneven terrain. About 3 miles per hour is the limit of current technology, he says.

Regularly calibrate sprayer for best results
SmartSpray sensors are placed in line with spray nozzles for tight tracking, Cordero says.

Regular calibration will help avoid unintended discharges or shutdowns, Salyani says. He recommends calibrating at least once per season, but especially after such system adjustments as replacing nozzles or switching between light and dense spray materials.

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