MAXIMISING competition against weeds and increasing herbicide options, while optimising yield and profitability, can be helped by using herbicide tolerance traits in crop hybrids.
Herbicide tolerance traits have been introduced by plant breeders in many Australian crops including, corn, canola, pulses, cereals, grain sorghum, summer forages and cotton.
Pioneer Seeds' trait and seed technology stewardship manager Kevin Morthorpe said in canola, for example, there were several herbicide tolerance traits and they were primarily available in hybrids.
"This means growers get both improved crop performance due to hybrid vigour and more flexibility in herbicide use patterns," Mr Morthrope said.
"Hybrids supercharge crop competition through a strong root system and vigorous growth.
"From an economic angle, hybrids optimise yield in both high input and tough environments, in fact, we see more growers selecting hybrids when producing canola in tough conditions."
In the past 15 years, the area sown to hybrid canola has risen to 47 per cent in Australia.
Mr Morthorpe said a diverse rotation of crops and pastures was one of the WeedSmart Big Six tactics which Pioneer Seeds endorsed.
"It helps to protect the longevity and effectiveness of herbicide tolerance traits," he said.
"Through an effective crop rotation you can tick off all the herbicide and non-herbicide tactics needed to drive down weed numbers," he said.
When making the most of a hybrid crop, Mr Morthorpe said best practice agronomy was critical as grain hybrids were vigorous plants that produced increased biomass and grain yield.
In order to do this, he said they must be supported with adequate crop nutrition.
"When properly fed, hybrids will provide increased crop competition and achieve greater water use efficiency compared to their conventional counterparts," Mr Morthorpe said.
"Growing a hybrid crop with herbicide tolerance traits does not equate to a full weed control program.
"These crops must be used within a diverse crop rotation and using herbicide tactics such as double knocking alongside cultural practices such as harvest weed seed control and crop competition to reduce seed set."
Hybrid crops also combine well with pre-emergent herbicides to achieve good early weed control and suppress seed set in any late germinating weeds.
It is not possible to use hybrid crops with herbicide tolerance to fix a weed blow-out as the technology is not suitable for salvage operations.
Mr Morthorpe said when Roundup Ready canola varieties were first released there was an expectation that these traits could be used to reverse a weed infestation, however this proved not to be the case.
"Hybrid crops are best used in low weed density situations where they can effectively drive down the weed seedbank," he said.
"They should be grown in rotations that include an effective double-break, brown manure crop or a pasture phase.
"Having hybrid crop options for both summer and winter growing seasons increases the opportunities to tackle weeds throughout the year or to use different fallow herbicides while maintaining the ability to safely grow crops in the following season."
Mr Morthorpe said in order to avoid problems with crop safety within the rotation, it was critical to maintain accurate paddock records to avoid applying herbicide to the wrong crop variety and ensure susceptible crops were not sown into paddocks with herbicide residues in the soil.
