- Correct recording of the variety of saved seed is vital, especially with herbicide-tolerant varieties
- Check a variety’s tolerance and herbicide requirements before seeding
- Understand and follow all herbicide label recommendations
Good record-keeping is an absolute must when harvesting, storing and sowing varieties with herbicide tolerance.
PHOTO: Bulla Burra
We all make mistakes; it is just that some are more costly than others. Treating a sown crop variety with the wrong herbicide because you thought the seed sown was tolerant is one costly mistake a few growers have made.
Most new varieties with herbicide-tolerance characteristics have this feature denoted in their name – for example, the wheat Grenade CL Plus, the barley Scope CL and the lentil PBA Hurricane XT – but others may not. And while a name might help when the seed is in a bag, you often cannot visually distinguish between the seed of an intolerant or tolerant variety.
Consequently, good record-keeping is essential when harvesting, storing and sowing herbicide-tolerant varieties.
Recent random DNA checking of grain receival samples against the variety declared by the grower found that up to 20 per cent of samples were incorrectly declared. In many cases the grower was declaring a variety carrying a higher end-point royalty. Given no one willingly pays more than they should, poor record-keeping becomes the obvious culprit.
While mis-declaration can potentially compromise grain marketers’ relationships with buyers, they can also be costly on-farm.
There are reports of whole paddocks of germinated wheat being killed by a herbicide, and lentil yield being halved when an intolerant variety was mistakenly sown in a paddock with soil residues of imidazolinone.
Ensuring home-saved seed is harvested from the correct areas and that silos are correctly labelled, with labels that endure until seeding, will help ensure variety integrity and avoid errors.
Even better than just entering the variety name in paddock records, some growers include it in the mapping software at seeding. This means what occurred is recorded, rather than what was planned. These maps can be particularly useful if multiple varieties are sown in a paddock.
Seeding maps can then be imported as background maps on the yield monitor at harvest, which can ensure the right areas and varieties are harvested for seed.
For the bins there are many ways of labelling. A cattle ear tag, written on with an all-weather marker pen and attached to bin outlets, is one method used by growers.
However, correctly identifying your seed is only part of the successful production of herbicide-tolerant varieties. Applying the correct herbicide at the right time and considering soil type, soil moisture status and climatic conditions that influence herbicide efficacy are other factors that need to be considered.
Varieties are often reported as ‘imidazolinonetolerant’ but there are several different ‘imi’ chemistries and some varieties may only be tolerant to one of these chemistries
For example, the new lentil variety PBA Hurricane XT has tolerance and a permit for applications of imazethapyr at label rates, but has only improved tolerance to residues of some of the other imidazolinone chemistries applied in the previous crop.
This is why it is important to read the variety brochures and herbicide labels and understand the impact of seasonal conditions and soil type on herbicide activity to avoid crop damage and reduced yields.
Some herbicide-tolerant varieties may only be tolerant under the conditions in which they were developed. For example, the wheat EGA Eagle Rock, which has improved metribuzin tolerance, was developed for Western Australian growers but its tolerance may not translate when sown on high-pH sandy soils in other states.
Information to help growers better understand herbicide tolerance within crop varieties can be found within state sowing guides and on the National Variety Trials website, where national research on crop varietal herbicide tolerance is published annually.
National Variety Trials
Paddocks need measured frost risk profile
Dry spring a disappointing close for many
GRDC Project Code
DAN00142, DAQ00136 (UQ00059-DAQ), DAS00100, DAW0019