Significant research and development over recent years has led to the development of the Clearfield Plus production system in Australia. The Clearfield Plus system offers superior crop tolerance to the Clearfield imidazolinone herbicide Intervix ®, in addition to broad spectrum knockdown and residual control of many key grass and broadleaf weeds.
The Clearfield Plus wheat system offers:
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- Superior yielding varieties
- Superior control of key grass weeds including brome grass, barley grass and volunteer cereals
- More flexible use rates and broader compatibility to allow prescription weed control
- Ability to apply at an earlier crop growth stage to reduce early weed competition
- Superior foliar uptake for quicker brownout
- Highly effective knockdown and residual grass weed and broadleaf weed control
- More flexible plantback periods and re-cropping opportunities
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The Difference Between Clearfield and Clearfield Plus Wheat
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Australian standard wheats are hexaploid wheats, in other words they are genetically comprised of three sets of paired chromosomes known as genomes. Simply put, Clearfield wheat (or one-gene) varieties have experienced a mutation in one of their three genomes enabling that genome to produce ALS enzyme that is unaffected by imidazolinone herbicides. The other two genomes lack the mutation and produce sensitive ALS enzyme. One-gene wheat varieties are therefore in effect one-third tolerant of imidazolinone herbicides (and two-thirds sensitive). Clearfield Plus (or 2-gene) wheat varieties have experienced a separate mutation on a second genome enabling those two genomes to produce ALS enzyme that are unaffected by imidazolinone herbicides. The other single genome lacks a mutation and produces sensitive ALS enzyme. Two-gene wheat varieties are therefore in effect two-thirds tolerant of imidazolinone herbicides (and one-third sensitive).
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Neither Clearfield nor Clearfield Plus wheat varieties are therefore immune from imidazolinone injury but obviously Clearfield Plus wheat lines are considerably more tolerant. This is demonstrated by the fact that CL JNZ and CL STL (the only two released varieties of one-gene wheat) do not have adequate tolerance of Intervix Herbicide at 600 - 750 mL/ha and have only restricted tolerance of Midas Herbicide at 900 mL/ha, the crop needing to be at the onset of 1st tiller at application. By contrast the new Clearfield Plus wheat lines are able to tolerate Intervix prior to the onset of tillering.
Note: Midas and Intervix herbicide cannot be used on non- Clearfield wheat varieties as crop damage will be extremely severe.
Development of new Clearfield Plus two gene wheat cultivars is ongoing in partnership with all major wheat breeding programs in Australia. Single gene Clearfield development has been discontinued.
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Clearfield Plus Wheat
