Spray Drift Management Case Study - Corrigin WA

My name is Neville Turner I farm in the Corrigin district which is about two hours east southeast of Perth. This year we’re cropping five thousand five hundred hectares predominately grains. We run a few sheep over summer buy and sell. The boomspray is the most used piece of machinery on the farm and always needs to be going and look you just its spraying’s one those things that’s got to be done on time. Had a few not-so-good years in terms of rainfall and there was nobody contracting in town and we’d bought a machine so people sort of wanted us to do a bit of work and it just sort of grew from there. I’ve been contracting now for I reckon this would be our 10th year.

01:02 - Now is our busy time of the year when we come into in-crop spraying with canola and lupins and desiccating. It’s probably the time where most of our work is done now. We’ve come a long way in the way we manage spray drift. 20 years ago most boomsprays had what they call an XR flat fan nozzle. So the faster you go the more pressure it pushes so the finer the droplet becomes. It mists it up a lot. We’re nowadays with the air inducted nozzle that takes air with the droplets. And they’re bigger also coarser droplets so they’re heading towards the ground so they sort of explode when they hit the target. At the moment we’re applying insecticides to canola to control the budworm. So up here we have our target litres a hectare which is sixty. Our application rate which is going out at the moment which is sixty so they have to both match up. If they don’t it’s a problem. Our speed which is 22 kilometers an hour.

02:06 - Our boom spray predominately runs at it between 22 and 25 kilometres an hour. A lot of people travel up to 30 I don’t think you get as good a job at 30 kilometres an hour And look even if you come down to 15 kilometres now you actually get a better job. But you’ve got a weigh up how much you’ve got to do and how much time you’ve got to do it in. Boom heights we’re 50 centimeter nozzle spacings so generally 50 you work on an average of 50 centimeters above your target. But we’re using lot higher water rates now in the last five years than we have been probably in the previous 20 and water rate is definitely doing a better job especially on the hard to kill weeds.

As most weeds become resistant over 02:52 - time with more applications so water rate is definitely making a difference. Insect spraying used to do a lot of 30 but even now we’re spraying insects at 60. It just seems to get a better coverage and a better job. But with that you’ve gone to bigger droplets so you’ve got less drift as well. In regards to minimizing spray drift it’s always better to have some wind than no wind. The wind forces the particles down into the crop more and rather than them drift up upwards into the atmosphere. But every day we’re conscious of wind speed direction humidity and what’s downwind. Buffer zones that constantly in your mind the location of the house, creeks dams, waterways, bush, the whole lot it’s just constantly in your mind. Some days we won’t even start if it’s they’re saying like there’s going to be rain around or it might be six hours before the rain but you’ve got to weigh up the rain fastness of the chemical you’re using so if it’s got four hours of rain fastness and there’s rain in six you can’t risk it. The most expensive spray job is the one that doesn’t work.

04:35 - I’ve never had an issue with an inversion doing damage but we constantly monitor it more towards the end of the day where we sort of worry about our air inversion layers you pick it up more with the dust than the drift nowadays. With the new 2, 4-D regulations we’re checking the label every time because you have to have it right. So and our, your speed, water rate your droplet size, which is ultra coarse it’s got to be there because that will otherwise if we don’t adhere to it and we have a problem we’ll lose 2,4-D. In the last 20 years we’ve come a long way in the way we manage spray drift with the introduction of air inducted nozzles and now I think the next step there is a quite a few boom sprays out there now what they called um PWM which is pulse width modulation so the nozzle pulses and irrespective of speed and water rate you can you can adjust your droplet size and I think that’s the next step in spraying and that’s what I would like to try next is it is the pulse width modulation. .