Nufarm is expanding the value of Terrad'or with a new pre-harvest registration in wheat, reinforcing its role as both a high-performing pre-seed knockdown partner and a targeted in-crop tool to reduce weed seed set.
Terrad'or has already seen strong adoption across Australia, particularly in pre-plant programs where it is commonly mixed with knockdown products such as paraquat or CRUCIAL, to improve control of hard-to-kill weeds. This new registration extends its value further into the season, giving growers another option to manage resistant and late-season weeds.
Reducing weed seed set in wheat
The new use pattern allows Terrad'or to be applied pre-harvest in wheat to reduce the viability of weed seeds, particularly annual ryegrass, as well as broadleaf weeds like wild radish.
Unlike other Group 14 herbicides, Terrad'or offers unique grass activity, making it especially effective on ryegrass—Australia’s most significant winter cropping weed.
Mitch Allen, commercial technical lead, said the new registration strengthens integrated weed management programs.
“Terrad'or is unique in this pre-harvest space. Unlike other Group 14s that mainly target broadleaf weeds, it gives us the ability to target key grasses such as annual ryegrass and reduce the amount of viable seed returning to the seedbank.”
Trials conducted over multiple seasons show that, when applied at the correct timing, Terrad'or can deliver around 50 per cent reduction in viable ryegrass seed set.
“We’re not talking about control, it’s about seed set reduction,” Mitch added.
“If we get our timing right, we can achieve meaningful reductions that complement other tactics like pre-emergents and harvest weed seed control.”
Timing is critical
Effective use depends on aligning crops and weed timing:
- Ideal timing: From Z75 (medium milk stage)
- Latest timing: Z83 (soft dough stage)
- Target: Ryegrass at or just after flowering.
At Z75, the grain is fully formed but still milky. This is the earliest safe application point.
David Keetch, field R&D innovation director, emphasized the balance between performance and safety.
“Getting the timing right is critical for both crop safety and maximum seed set reduction. When applied at Z75 or later, we’ve seen excellent outcomes with no yield impact while still reducing ryegrass seed viability,” he shared.
Applying too early can lead to crop injury, yield loss and residue risks, while applying too late reduces effectiveness as weed seeds continue to mature.
No yield impact when applied correctly
Trials show that when used from Z75 onwards, Terrad'or has no impact on yield or grain quality. Minor effects such as head spotting or browning may occur, but these do not translate to grain staining, yield loss or downgrades, giving growers confidence in its use.
Supporting pre-seed programs
Alongside its new wheat registration, Terrad'or remains a valuable tool in pre-seed knockdown programs, where it:
- Improves control of hard-to-kill weeds
- Supports resistance management
- Enhances both translocated and contact herbicide performance.
This dual use positions Terrad'or as a season-long solution, from fallow through to harvest.
Application matters
As a contact herbicide, coverage is critical. Recommended application practices include:
- ~100 L/ha water rate
- Coarse spray quality
- Correct boom height for canopy coverage.
“Maximizing coverage is key to getting the most out of Terrad'or,” Mitch said.
A complementary tool
Terrad'or is designed to work alongside existing strategies, not replace them. Integrated with pre-emergents, knockdowns and harvest weed seed control, it provides a valuable additional lever.
As Mitch summarized, “It’s not a standalone solution, but it’s a very useful tool. If we line up crop and weed timing, it can make a real difference in reducing the seedbank for future seasons.”
With expanded use in wheat and continued strength in knockdown programs, Terrad'or offers growers greater flexibility to protect current crops while reducing future weed pressure.
This article was written by Nufarm for Seasons.
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