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JUDIE STEEVES Calibration education, anyone?


Sprayingmay be simple, but it’s a huge waste of time and resources if done improperly. By Judie Steeves


A


re you spraying your new-style, densely-planted orchard the same as you sprayed those big old, widely-spaced trees you used to grow? Are you still using the same equipment? If you’re growing grapes, do you alter spray techniques seasonally, depending on the amount of canopy?


Spray drift is a costly waste of chemicals, can damage off-target crops, contaminate watercourses, and affect neighbouring properties. Agricultural engineer and biologist Andrew Landers of Cornell University in New York advised growers at this year’s horticultural symposium that it’s vital you get the liquid from your sprayers into the canopy; that the engineering design be biologically effective. Sprayers must be calibrated for the modern orchard, he


JUDIE STEEVES


Andrew Landers, of Cornell University, was a featured speaker at this year’s horticultural symposium.


emphasized.


“There have been changes in crop density, row spacing, canopy width and number of rows per acre, yet sprayer design is still back in the 1960s.”


“The challenge is to improve


deposition, reduce drift and produce quality fruit,” Landers noted, adding, “Lazy growers just spray clouds of pesticide into the air, which looks bad to the consumer and isn’t effective.” He told growers that spraying is simple, but they need to use the right chemical at the right time and at the right rate for an effective application. Airflow must be taken into account. The direction, speed and volume of the air all need to be considered, he advised.


The forward speed, pressure and nozzles affect the liquid you’re spraying, while the air is affected by engine speed, air speed, air volume and direction of spray.


The nozzle tip has a hole in it that determines the rate of flow, depending on the hole size and the pressure, but by changing the nozzle output to double the output, you also need to increase the pressure four- fold, Landers said.


Nozzle and pressure create the droplets, but air carries the droplets. Droplet size matters, he emphasized. Smaller droplets improve coverage and the adhesion of the spray, while larger droplets offer mass and momentum, but longer evaporative


British Columbia FRUIT GROWER • Summer 2016 25


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