| With the increasing adoption
of Roundup Ready cotton in the market, the issue of controlling volunteers
is becoming more urgent.
Early seedling volunteer Roundup Ready cotton needs to be eliminated
prior to sowing because of its ability to carry root and seedling diseases.
Roundup Ready volunteers can also pose a threat to conventional crops.
Recent trial work in NSW and Queensland has supported Nufarm’s
confidence in bromoxynil as the best active ingredient for controlling
Roundup Ready volunteers. Nufarm manufactures three bromoxynil-based
chemicals – Bromicide 200 (containing 200g Bromoxynil), Bromicide
MA (200 g Bromoxynil and 200g MCPA) and Broadside (140g Bromoxynil,
280g MCPA and 40g Dicamba).
Frank Taylor, Technical Officer for Nufarm based in Toowoomba said the
best results in controlling volunteer Roundup Ready cotton could be
achieved using a rate of 1.5 litres per hectare of Bromicide 200, and
if other weeds were present it could be tank-mixed with Roundup.
Frank conducted replicated trials on the Darling Downs in 2002–03,
while his counterpart in NSW, Harry Pickering, ran trials at Trangie.
Frank said that a major advantage in using Bromicide 200 to control
Roundup Ready volunteers was that there were no plant-back issues. He
demonstrated this by treating his trial site for volunteers the day
before the grower planted a crop.
“Because there are no residue issues, a grower has the flexibility
to spray out volunteers right up until the day he plants,” said
Frank.
Another advantage in using Bromicide 200 is that there are no vapour
drift problems.
“Bromoxynil is a fast acting chemical which works on contact,
requiring good coverage for maximum effectiveness.
“Ideally, weeds should be small, up to four leaf in size, although
our trial work showed that the product is effective at up to six leaf.”
Nufarm plans to apply to renew a permit for Bromicide 200 to control
volunteer Roundup Ready cotton for this season. Nufarm has also recently
registered the product for cow vine and peach vine control in fallow
weed control in NSW, the ACT and Queensland.
In addition, Bromicide 200 and Bromicide MA are now registered to control
common sow thistle in cereals in northern NSW and Queensland.
“This follows several seasons of successful trial work with both
Bromicide 200 and Bromicide MA,” said Frank.
Bromoxynil differs from other Group C herbicides in that there have
been no cases of resistance recorded, making it an excellent choice
in weed management plans.
“No resistance in normally susceptible weed species has been identified
despite more than 30 years of use worldwide,” said Frank.
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