Cereal growers should spot fields with significant brome populations and identify the brome species at harvest to ensure autumn weed control plans are appropriate to the threat, says Dow AgroSciences.
"Brome species are most effectively controlled by autumn herbicide applications, but are often omitted in the rush to get crops drilled and pre-emergence herbicides applied," warns Stuart Jackson, Dow’s cereal herbicide specialist.
"If growers can identify those fields with significant populations of brome and ryegrass they can be prioritised for autumn applications.
"Good field observations pre-harvest should include population density and brome species identification, since post-harvest control measures for sterile and great brome are different to those needed for soft, meadow and rye bromes."
For sterile and great brome, early post-harvest shallow cultivations are best.
Seeds need to be buried or covered to break dormancy and encourage a germination flush before spraying off with a non-selective herbicide.
However, seeds of soft, meadow and rye bromes need to be left on the soil surface for one month to ripen before cultivation and subsequent spraying off with a non selective herbicide.
If buried, immature seed become dormant and survive longer in the soil.
Herbicide applications should also be targeted at the brome species present.
Great and sterile brome species can be the most difficult to eradicate so a robust autumn spray programme is required.
These grassweeds are more effectively controlled when small (Growth Stage 11 – 13) and actively growing.
Autumn spray programmes should include a pre-emergence application soon after drilling (such as 4.0 l/ha Crystal (flufenacet+pendimethalin)) followed by an appropriate post-emergence contact graminicide such as Broadway® Star (pyroxsulam+florasulam) with adjuvant, and a residual partner such as Stomp Aqua (pendimethalin).
Timing post-emergence sprays to control meadow, soft and rye bromes can be more flexible.
While autumn applications are still the gold standard, providing a pre-emergence spray is applied, a post-emergence application of Broadway Star can be applied in autumn or delayed until early spring if necessary.
