The last decade has seen a major issue with the introduced weed Navua sedge (Cyperus aromaticus) for graziers in wet, tropical regions of northern Queensland.
Navua sedge originated from Africa and will compete aggressively with preferred pasture species by forming dense stands. This is particularly evident if pastures are overgrazed, with the sedge rapidly taking over large areas.
It is generally unpalatable with little to no feed value for grazing cattle.
Many herbicide options have relatively long grazing withholding periods, (WHP) of up to ten weeks, which can limit the options graziers have to maximise pasture productivity and also sell their cattle in a timely manner.
Corteva North Queensland territory account manager Kate Daly said the company had been aware of the shortfalls of current Navua sedge control options and had looked at its portfolio to address the issues.
Navua sedge has become a major issue for graziers in wet, tropical regions of northern Queensland.
“Ubeniq Rinskor active herbicide has been registered in Australia since 2018 for post-emergent weed control in rice,” Ms Daly said.
Ubeniq is based on Rinskor which is a new arylpicolinate active ingredient in the structural class of synthetic auxin (Group 4) herbicides.
It has an extremely attractive environmental profile and won the US EPA Green chemistry award in 2018. “For the past five years Corteva has been trialling Ubeniq in grass pastures and found excellent activity for the control of Navua sedge,” Ms Daly said.
“Along with the excellent environmental profile, what is particularly pleasing is the very short grazing withholding period of just three days which will allows graziers to treat their pastures and quickly get stock back onto the paddock.”
She said it is available as a cost-effective option and a tool graziers can use to reduce the amount of sedge on their property over several years.
“Any areas of sedge will have a large seed bank, so graziers will need to work in the long term to reduce the amount of this weed in their paddocks.
“Ubeniq now provides an option to ‘Get the edge on sedge’ and return problem paddocks back to productivity.”
Ms Daly said Ubeniq Rinskor active herbicide had the ability to improve pasture productivity and increase carrying capacity.
“It is also rainfast in one hour which ensures good efficacy is achieved quickly after application and gives peace of mind in wet tropical regions where rain is often imminent.
“Ubeniq can be applied when Navua sedge is at the seedling stage, prior to flowering.
“For best results apply to actively growing grass pastures two weeks after grazing, in spring or summer, at a rate of between 100 and 150 mL/hectare. A second application 10–12 weeks later may be necessary to control the next germination of sedge.”
Uptake spraying oil is recommended to maximise the efficacy of the product.
Ms Daly said an ideal time to apply Ubeniq is right after significant rain, with the herbicide working well on sedges when there is good soil moisture available.
“It also works rapidly in warmer, wetter weather conditions.”
Ubeniq can be applied via boom or spot sprayer and has activity on a range of other weed species found in northern region pastures.
“Corteva is working on identifying other weeds controlled by Ubeniq in this region and these will be added to the label when relevant data is generated,” Ms Daly said.
“Grazier should be aware that it does have activity on pasture legume species so will need to take this into consideration when deciding where to utilise the product.”
Close-up of Navua sedge (Cyperus aromaticusis).
She said the registration of Ubeniq Rinskor active herbicide for the control of Navua sedge is exciting for graziers in north Queensland.
“Navua sedge was first noticed on the footpaths of Cairns in 1979 and has spread in all directions to be of great concern for pastoralists today.
“It grows from seed and vegetative reproduction so the ability of Ubeniq to effectively control sedge, with both a short withholding period and excellent rainfastness is very positive.
“By controlling Navua sedge, graziers can improve pasture production and make better use of the available feed.”
The herbicide can also be used in sorghum, with a recent registration to control caltrop (yellow vine) (Tribulus terrestris). Ubeniq also has fallow and industrial weed control claims on the updated label.
Ms Daly said caltrop has been a difficult weed to control in sorghum in recent years, so Corteva set about looking at an alternative herbicide option. The very short grazing withholding period will also make the use of Ubeniq in grazing sorghum an attractive option.
To broaden out the weed spectrum, Ubeniq is recommended to be tank-mixed with Starane Advanced and Hasten for excellent control of caltrop and other problem weeds.
