Featured: Weed wizards

By: Anna Game-Lopata

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Grain farmers Barry Gray and Simon Kerin in Western Australia are trialling alternative methods for weed management at harvest.

Featured: Weed wizards
Barry Gray and son Scott are windrow burning to destroy ryegrass seeds at harvest on their grain farm near Kukerin, WA.

Barry Gray, whose Albany Port Zone property near Kukerin has been in the family for generations, had relied on herbicides as the major weed control measure to control ryegrass and wild radish.

As he was dry sowing crops more frequently, Gray is making greater use of pre and post emergence herbicides rather than knock-downs.

He says export hay paddocks are always treated with herbicides, but recent tests show ryegrass populations are now resistant to groups A and B herbicides.

As a result Barry decided to move towards weed seed management at harvest.

"We’ve tried several things," Gray says. "Initially we towed chaff carts behind our harvester to collect the weed seeds, however just recently we’ve decided to go more towards windrow burning."

Having used the chaff cart for three years Barry wasn’t satisfied with its operation. 

"It wasn’t easy [to use] and it wasn’t collecting all the seed," he says. "But with the windrow I know every seed that goes in the harvester is in that little pile of straw and if I get a hot enough fire I’ll kill it all.

Harvested using his newly purchased New Holland CX8080 header, the barley crop is cut as low as possible to ensure all the weed seeds are collected in with the straw and grain.

The straw is dropped in a narrow windrow approximately a metre wide and the chaff fraction drops on the straw rather than on the ground as in a traditional chaff cart operation.

To achieve this effect, Gray designed his own modification to the conventional header, which he prefers to rotary models he says tend to pulverise and shatter the straw making it harder to bale.

Placing chaff on top of the straw ensures the weed seeds are in the hottest part of the fire when the stubble rows are burnt in autumn.

Just over ninety kilometres south of Barry Gray’s property, the Kerin family has chosen the chaff cart over windrow burning

Their 5200 hectare section of land dedicated to cropping grain and sheep farming in Katanning also has a major problem with ryegrass, wild radish and wild oats.

Purchased second hand, their chaff cart cost just $16,000 and $15,000 to adapt. It came with a vacuum blower kit attached, which the Kerins removed.

Instead, they added a draper type conveyor system based on one they’d observed [fellow grain farmer] Lance Turner in Pingelly had developed.

The hydraulics on the header were also modified so that the chaff cart could be operated from the header and cameras added to the back.

"The cart has a long draw bar which makes it ideal for adding a conveyor," Kerin says, "however care needs to be taken when turning as the shaft is less flexible.

"Dropping the heaps of chaff in rows across a paddock makes them easier to manage when burning later and keeps them in a known area in case additional management like follow up spraying is required."

"We make sure we keep the heaps of away from structures, trees and fences," he adds, "as this reduces the risk of fire damage when burning later in the season."

While Kerin says it’s hard to judge, he thinks the chaff cart system has definitely decreased the ryegrass, but estimates it will be at least three years before he can really get a sense of how well the chaff cart and conveyor system is working.

Despite the challenges, Barry Gray believes his method of windrow burning is definitely having an impact, reducing weeds 50 per cent year on year.

"We still have blowout patches were still not on top of the ryegrass," he admits.

"We’ve had good success with radish control. I do have paddocks I don’t use broad leaf spray any more. I get the odd plant, but I’m quite confident I’ll get it all in that windrow and it’ll be burned in autumn.

"For broadleaf weeds we are using less and less chemical all the time."

Read the full feature in the December issue of NewFarmMachinery magazine on sale December 23. Subscribe to the magazine to receive the issues straight to your doorstep.

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