Control of winter weeds

Controlling of winter weeds - many new options available

Cropping
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NEW herbicide options for weed control have been or are soon to be released.

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Agronomists and farmers assessing performance of new herbicides at a Corteva Agriscience field day at their Breeza site. A range of new herbicides for winter cropping have been registered in recent times with more to come.

Agronomists and farmers assessing performance of new herbicides at a Corteva Agriscience field day at their Breeza site. A range of new herbicides for winter cropping have been registered in recent times with more to come.

New herbicides with a variety of chemistries with different modes of action to assist with management to avoid weed herbicide resistance, have recently been added to options for improving weed control in winter crops.

High level weed control is a result of integrated control measures that include competitive crops as well as careful selection of appropriate herbicides.

High level weed control is a result of integrated control measures that include competitive crops as well as careful selection of appropriate herbicides.

These are detailed in the latest edition of the NSW Department of Primary Industries (DPI) booklet "Weed Control in Winter Crops" (2020), authored by Greg Brooke and Col McMaster, Research and Development Agronomists, Trangie and Orange respectively, and Penny Heuston Project Officer, Northern Cropping Systems, Trangie.

High standard fallow weed control is vital for moisture conservation as well as for avoiding weeds developing resistance to herbicides.

High standard fallow weed control is vital for moisture conservation as well as for avoiding weeds developing resistance to herbicides.

Products not included in the booklet, and likely to be released in the future are detailed in a recent Grains Research and Development Corporation (GRDC) update paper "New chemistry - what's new, what's coming and how to keep them for longer" authored by Greg Condon, Grassroots Agronomy.

Some of these are likely to further add to options to better manage weed control as well as better manage to avoid weeds developing resistance to herbicides.

Luximax (750g/L cinmethylin) is a pre-emergent herbicide with a unique mode of action (Group Z) for use in wheat. It offers a high level of residual control of annual ryegrass (including biotypes resistant to existing mode of action groups including Group K). Cost is around $39/ha. It is compatible with some other herbicides

Frequency is a new post-emergent, Group H herbicide for control broadleaf weeds in wheat, durum and barley, with versatility in tank mixing options (bromoxynil, MCPA) to tailor for specific weed sizes, spectrums and resistance issues.

Condor is a new combination (10g/L pyraflufen-ethyl as in Ecopar plus 375g/L MCPA as the potassium salt) registered for controlling broadleaf weeds in wheat, barley and oats. It is a post emergent option with two modes of action for improved control and resistance management to seedling weeds.

ForageMax (100g/L halauxifen plus 50g/L aminopyralid) is registered for use in 4-8 leaf canola for controlling several broadleaf weeds. It also has a registration in grass pastures (not legumes) for control of some difficult broadleaf weeds.

Like for several herbicides there is a "do not graze or cut treated crops for stock feed" restriction period, in this case for two weeks after application. Cost is around $40/ha.

Crucial is a new glyphosate product (600g/L) that is a triple salt, triple surfactant liquid formulation. It has the full range of registrations from previously marketed Weedmaster labels.

Sledge is a new registration (25g/L pyraflufen-ethyl) to replace Ecopar (20g/L pyraflufen-ethyl) for use before sowing a winter crop, starting a winter fallow. The label has been updated with detail for controlling additional weeds such as heliotrope, wild radish, sow thistle and cotton volunteers. It is a Group G product.

Pyresta Xtreme LV (2.1g/L pyraflufen-ethyl plus 600g/L 2,4-D) replaces Pyresta. It is a low volatile 2,4-D herbicide for improving brownout in a range of broadleaf and grass weeds when mixed with glyphosate-based products (spike).

Terbyne Xtreme (875g/kg terbuthylazine) is a new registration approved for application to fallows before planting mung bean, soybean, barley, oats and wheat. Again, there are significant label plant back details.

Products detailed in Greg Condon's paper include Ultro for use as a IBS (incorporate by sowing) in some pulse crops, Luximax, a ryegrass control product, Mateno with a new mode of operation control in wheat and barley, especially in stubble retention systems.

Also Gallery for wild radish control, Overwatch, with various grass control in pulses, Callisto, with a wide group of broadleaf weeds control in wheat and barley, as well details of several other promising new products.

It is important to check for a number of aspects before deciding on a herbicide, including grazing plant back periods, residual life, compatibility when mixing with other products, timing, rate, and plant back time.

These are available on herbicide labels as well as generally covered in the weed control booklet.

Next week.

Monitor crop diseases carefully.

  • Bob Freebairn is an agricultural consultant based at Coonabarabran, and can be contacted by email robert.freebairn@bigpond.com or contact 0428 752 149.
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