The Guest family uses a WEED-IT Quadro optical spot sprayer to limit chemical build up and deal with troublesome weeds on Thorburn, their farm north of Griffith, NSW.

The Guest family uses a WEED-IT Quadro optical spot sprayer to limit chemical build up and deal with troublesome weeds on Thorburn, their farm north of Griffith, NSW.

Rodney and Leonie Guest are the owners of the 2400-ha property, which mainly produces wheat, barley, and peas. Their daughter and son-in-law Tanaya and Sandy Nixon live on the farm. It is Sandy who operates the WEED-IT.

The soils on Thorburn are Mallee sandy loams with some sandy rises that have lower organic carbon levels. Rodney says they were finding residues of Roundup and 2,4-D building up in those low carbon areas, which limited following crops.

Legumes and canola are sensitive to spray and could not be planted on the sandier soils.

To reduce the amount of chemical they use, and therefore residue levels, is one reason why they decided to purchase the WEED-IT Quadro.

The Quadro is the latest version of the WEED-IT. It has new blue light sensors every metre along the boom and each sensor controls four nozzles. When it ‘sees’ the green of vegetation it directs spray solely at that weed.

The result has been a huge reduction in the amount of chemical they require.

Part of the farm rotation is to leave 400 ha fallow. This serves as a weed break and also conserves moisture for the next crop.

Sandy sprayed the fallow land, just after getting the Quadro in September.

I used just 25 litres of chemical spot-spraying, compared to 1000 litres if I had sprayed it all. There are huge savings to be made

Rodney Guest, “Thorburn”, NSW

He says cutting down the amount of spray the family uses is good for the soil, the environment, and the back pocket. In an increasingly regulated industry it’s all a positive, especially reducing the use of 2,4-D.

“It is a big advantage being able to use less chemical. We can afford to use more expensive chemicals that better target a troublesome weed.

“One of our problem weeds is feathertop Rhodes grass. Last summer to control it, we went out in utes most of the summer and chipped it out by hand.

“Now we are going to use the Quadro as we can afford a more expensive chemical, which has to go on at high rates.”

Sandy also hopes the Quadro will delay the development of herbicide-resistant weeds. At the moment they are just starting to see resistant ryegrass and they are hoping to get on top of it by spot spraying during the fallow rotation.

The Quadro has two tanks so it can blanket spray and spot spray at the same time. The main tank is 4000-litres and the hot tank for spot spraying is 1100-litres. Other models available include the WEED-IT 7000 with 7000 litre main tank and 1500 litre hot tank.

The two tanks can hold different chemicals and spray at different rates.

Sandy has yet to use this feature, but says in future he plans to spot spray weeds whilst blanket spraying pre-emergents.

“It gives us options. If a paddock is clean we can do the whole paddock at a low rate and if there is a scattering of weeds we can give them a bigger hit.”

When he is only spot spraying, Sandy uses the main tank for extra water. This means he does not have to make up as much spray at once.

He operates the WEED-IT at 15-20 kph. It has a 24m ground-gliding boom, so he can cover lots of ground in a day. Boom width on the larger WEED-IT 7000 is 36m.

The WEED-IT system of sensors can be added to any type of sprayer. The Guests purchased their trailed WEED-IT Quadro through their local Croplands dealer in Griffith.

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