When applying chemicals to crops, where the chemical is delivered is sometimes more important than how much is delivered.
A team of Agricultural Research Service and university scientists has developed a new laser-guided spraying system that controls spray outputs to match targeted tree structures. Such a device would help growers of nursery, orchard, and grape crops apply chemicals with more precision and less waste.
“Conventional spray application technology requires excessive amounts of pesticide to achieve effective pest control in floral, nursery, orchard, and other specialty crops,” says ARS agricultural engineer Heping Zhu. “This challenge is now overcome by our automated, variable-rate, air-assisted, precision sprayer. The new system is able to characterize the presence, size, shape, and foliage density of target trees and apply the optimum amount of pesticide in real time.”
The research team includes Zhu, USDA engineer Richard Derksen, research leader Charles Krause, and colleagues at Ohio State University, Oregon State University, and the University of Tennessee.
The system has many parts that have to work together with precision. “It integrates a high-speed laser-scanning sensor in conjunction with a Doppler radar travel-speed sensor, an automatic nozzle-flow-rate controller, an embedded computer, a touch screen, a manual switch box, and four five-port nozzle manifolds on each side of the sprayer,” says Zhu. The laser-guided sprayer can treat several rows of nursery trees at a time.
The team conducted field trials to assess the technology’s performance in six commercial nurseries in Ohio, Oregon, and Tennessee. “Our field experiments showed that the precision sprayer, when compared to conventional sprayers with best pest management practices, consistently sprayed the correct amount of chemicals, despite changes in tree structure and species. It also deposited the spray more uniformly on the targets, even at different growth stages,” says Zhu.
“Pest control with the new sprayer was comparable to that of conventional sprayers, but the new sprayer reduced average pesticide use between 46 and 68 percent, with an average pesticide cost savings of $230 per acre for ornamental nurseries. The cost savings can be much higher for orchards and other fruit crop productions,” he says.
Additional tests in an apple orchard demonstrated that the new sprayer reduced spray loss beyond tree canopies between 40 and 87 percent, airborne spray drift by up to 87 percent, and spray loss on the ground between 68 and 93 percent.
“This new precision spraying system has significantly advanced the technology for efficient variable-rate pesticide applications, and it offers an environmentally responsible approach to controlling insects and diseases,” says Zhu.
Zhu and his colleagues received a USDA National Institute of Food and Agriculture grant to develop the system. The technology and performance evaluations were described in several papers in the journal Transactions of the ASABE.