Rate controllers on air-assist sprayers

There are many advantages to using rate controllers, but their primary role is to maintain a constant application rate. All sprayers change speed on hills, at row-ends, or in response to surface conditions. Since flow from an uncontrolled sprayer is constant, the application rate varies significantly (up to 40% in hilly conditions). Rate controllers compensate […]

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Why do sprayers tip?

This short article is a reminder for sprayer operators to respect the possibility of tipping a sprayer. Every spring I catch wind of someone tipping over. When I can ask the operator questions I start with “Is everyone alright?” and “Was the sprayer full?“. Hopefully the answers are “Yes” and No“, but not always. The […]

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Reducing Selection Pressure for Herbicide Resistance

Herbicide resistance has been called the number one threat to conventional herbicide-based weed management strategies. Since the 1970s, the number of cases of herbicide resistant weeds has shown a linear increase both globally (currently at about 500 documented unique weed species x mode of action cases) and within Canada (at about 70 such cases), according […]

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Thermal Inversions for Sprayer Operators

The Earth’s Atmosphere. The illustration of the Earth is to scale, but the landscape is not. Our focus in on the Surface Boundary Layer.

In April 2014, NDSU extension published an excellent factsheet explaining what thermal inversions are, how to detect them and how they affect pesticide spray drift. That factsheet inspired this article. The Atmosphere The Earth is surrounded by a layer of air called the atmosphere. Think of it as a sheet of liquid percolating and flowing […]

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Airblast Nozzles – Reading Nozzle Tables

The author looking up nozzle rates during a spring calibration. The operator was running at 190 psi, but the catalogue only listed 180 psi and 200 psi. When span is only 20 psi, it’s fairly safe to approximate the output. When the table only lists in 50 psi increments, it is more difficult to determine the rate without testing the output. This issue usually occurs at pressures above 200 psi, and that’s very high for most horticultural operations. Consider using a lower operating pressure, if possible.

Airblast operators should know how to read a nozzle table. They are found on dealer and manufacturer websites as well as in their catalogs. Table layout varies with brand, but they all relate a nozzle’s flow rate to operating pressure. The better tables also provide the spray angle and the median droplet size (i.e. spray […]

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