Weeding out space invaders

August 02, 2017

The outlook for weeds in a zero row space environment (left) compared to a conventional 375 mm row space configuration.

Swan Hill no-till grain grower Leigh Bryan doesn’t shy away from an unconventional idea.

His crop-guided shielded sprayer is working a treat, he is confident with chaff lining and now he is testing the possible advantages of zero row spacing.

His aim is weed-free paddocks with crops growing at their full potential across the 2400ha of cultivation, across multiple farms within 30km of Swan Hill.

‘‘Being crop-guided, the shielded sprayer provides precise control over weeds and crop volunteers,’’ Mr Bryan said.

Using the shields strategically over the past seven years, Mr Bryan has drastically reduced weed numbers and can concentrate on preventing seed set in just the odd plant here or there. The shields allow Mr Bryan to use more cost-effective pre and post emergence herbicide options to prevent seed set of grass and broadleaf weeds in cereal crops.

‘‘The shielded sprayer also makes it possible for me to crop top at the optimum time to have maximum impact on weed seed set without damaging the crop, regardless of the crop maturity stage,’’ he said.

Mr Bryan has been chaff lining now for three years and says depositing the chaff-only fraction in a narrow line between the harvester wheeltracks is a very effective way to keep weed numbers low.

‘‘Dropping the chaff line between the wheeltracks, rather than into the wheeltracks, minimises disturbance of the seeds, reduces weed seed contact with soil and promotes more rotting down over summer.’’

Last year Mr Bryan used the chaff lining chute in all crops except canola and found there was no problem pulling the tines through at planting this year.

‘‘We first tested the idea in clean paddocks hoping to keep them clean,’’ he said.

‘‘We are now completely confident in the system and will be using the chaff lining chute in all crops across the farm this season. It has proven particularly valuable in lentil crops.’’

For the last three years, Mr Bryan has also been trialling zero row spacing in a bid to capture optimal yield from his crops. The planter has been fitted with splash plates that spread 35 per cent of the seed at random while the remaining 65 per cent of the seed is sown conventionally, down the tube.

‘‘This will only work in relatively clean paddocks,’’ he said.

‘‘With no trifluralin applied the in-crop weed control is reliant on strong crop competition and very, very low weed seed bank. Next year I will be looking at different pre-emergent herbicide options and how they might fit in this system,’’ he said.

“There are others playing around with the idea of zero row spacing too and I think it has potential,’’ he said.

Once weed numbers are low, Mr Bryan said it is relatively easy to keep them low through the consistent use of both herbicide and cultural practices.

‘‘When weed numbers are low it is possible to look at ways to improve yields and reduce production costs,’’ he said.

‘‘That’s what I hope to achieve with zero row space planting, supported by crop rotation and chaff lining to manage survivors. If there is evidence that weed numbers are increasing, then we have other tools at the ready to stop a weed blow-out,’’ he said.

■For more information about testing for herbicide resistance, visit the WeedSmart website:

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