Stopping weeds in their tracks!

"Spinning wheels on your boom-sprayer displace air. The result is usually to displace smaller droplets away from the wheel tracks; we have all seen this! That’s where nozzles with bigger droplets with more momentum are a good choice behind the wheels, regardless of what else is on the boom."

I have also been reminded since originally posting this article that "dust churned up from wheels will deactivate some products (e.g. Glyphosate) and that wheels may stir up and redistribute weed seeds and residues too" Thanks Jason Deveau for that ;)

All the more reason for getting serious about dealing with the problem!

What to do about it?

The right nozzle to have tracking behind sprayer wheels ought to;

  1. Produce big droplets (with greater momentum).
  2. Spray backwards, to compensate for forward movement of the sprayer. We suggest a twin-fan nozzle here as half of the spray pattern is directed rearward even on a vertically mounted nozzle.
  3. Produce a 'double pass' over the target using a twin fan.

It just so happens that we have the right nozzle. What a happy coincidence ;)

We suggest this, our premium Air Twin Ceramic (ATC).

To make it easy, we have put together a "wheel TRACKER" kit, comprising of two ATC nozzles with the required caps, adaptors, and seals to suit your machine.

Upping the rate a little.

Our recommendation here is to aim for a higher rate by simply using the next size nozzle up, behind each wheel. This would have a negligible impact on the overall flow-rate of the boom, but will give you a higher rate of application within the wheel tracks, which helps compensate for what is being displaced by turbulence.

Let’s look at what would happen at say 3 Bar pressure.

  • Green 015, 0.6 Lit/min - Main Boom
  • Yellow 02, 0.8 Lit/min - Behind Wheel - Difference 0.2 Lit/min, (33% higher rate).
  • Yellow 02, 0.8 Lit/min - Main Boom
  • Purple 025, 1.0 Lit/min - Behind Wheel - Difference 0.2 Lit/min, (25% higher rate).
  • Purple 025, 1.0 Lit/min - Main Boom
  • Blue 03, 1.2 Lit/min - Behind Wheel - Difference 0.2 Lit/min, (20% higher rate).

You would have to give some consideration to your chemical mix here and whether or not the %age increase in rate would be problematic. On the balance though, a little extra juice in the target zone may be very helpful. But check first please ;)

Article by David Young

Other articles

Read our other articles here.