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Australians showing the Yanks how to manage weed seed banks

Our American cousins now appear to be getting on the “Integrated Weed Management program” after a collapse of their weed control systems over the last decade. Colleagues from Western Australia are going to show them some of the techniques developed in Australia.

Following is an extract from the “Delta Farm Press”, August 6, 2014

Australian producers, who have been fighting herbicide-resistant weeds as long or longer than their American counterparts, have been thinking about the concept and have developed some tools to prevent the random distribution of weed seed.

One of those is the chaff cart, which Jason Norsworthy, a professor of weed science at the University of Arkansas, had on display at the “Respect the Rotation Pigposium” at the Northeast Research and Extension Centre in July.Jason Norsworthy inspecting a sybean field choked by Palmer amaranth (Pigweed in US). Image: Fred Miller

“We’ve done work on Palmer amaranth (pigweed) where we found that about 99 per cent of the amaranth seed that is harvested goes into the header, and a good portion of that is going to exit the header and be spread back on to the field,” he said.

“The idea of the chaff cart from the Australians is they use the cart in wheat to capture all (sic) of the ryegrass seed,” he noted. “Then we have piles of chaff that are laced with weed seed that we can dump in a field and burn.”

Norsworthy tested his chaff cart during soybean harvest at the Northeast Research and Extension Centre, located at Keiser in northeast Arkansas, last autumn.

“We were quite successful in catching the soybean chaff, catching the amaranth seed and destroying those during the burning operation,” he said. “In addition to that, we’re also looking at narrow-windrow burning.”

To accomplish that, Norsworthy and his associates take the spreaders off the header, form a narrow chute on the back of the header and windrow the soybean chaff. “The soybean chaff, again, is laced with weed seed, and we burn that shortly after harvest.

“I have a graduate student who is conducting research on how effective we can be at destroying the weed seed in soybean chaff, which obviously is quite different than the system they’re using in Australia.”

Another tool Norsworthy and his researchers are looking at is the Harrington Seed Destructor, which is pulled behind the header. (For more on this implement, see http://www.youtube.com/watch?v=wZUSmRdafAs.) As chaff enters the Destructor, any weed seed contained is destroyed before being passed back onto the field.

“Obviously, there isn’t any loss of the chaff or straw because it essentially is a grinding operation,” said Norsworthy.

Ray Harrington, the inventor of the Harrington Seed Destructor, and Lance Turner, an Australian grower who uses a chaff cart similar to Norsworthy’s will be at Keiser for a meeting on the afternoon of August 18.

“We’ll also have a grower from Australia talk about the impact of narrow windrow burning those practices have had on resistance management in the Australian system and what some of our growers in the U.S. could do to try to manage herbicide-resistant weeds,” said Norsworthy.

“At the end of the day, the key to resistance management is bringing down the soil seed bank,” he said. “We’re doing a tremendous amount of chopping and hand removal at this point, and these are strategies we could possibly integrate into our production systems to reduce the amount of weed seed going back into the soil seed bank.”

Form more images of Palmer amaranth  go here.

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