Identify Bromes to optimise control 

As bromes become visible in winter cereals, growers are encouraged to take the time to identify the species, to optimise control throughout the rotation. Technical Support for UPL, Rob Adamson, discusses the merits of weed ID and some of the options that are currently available from chemistry.

Rob Adamson, Technical Support for UPL UK & Ireland

 

“Bromes are highly competitive grass weeds. They’re similar to wild oats in that it only takes five plants/m2 to cause a yield loss of 5% in cereal crops.

Not only are they competitive, but they vary in species and require different control methods. The UK has two groups of brome species – anisantha (sterile/barren and great bromes), and bromus (soft, meadow and rye bromes). Because they need different methods of control, this means that successfully identifying the species is crucial.

The best time to identify a species is once the seed heads are visible in June and July and to help with this, the AHDB has a guide online. This can then be used to inform cultural control methods, as well as herbicide choices.

Cultural control options vary between the anisantha and bromus species, due to difference in the maturity of seeds at harvest, and the impact on dormancy cultivation can have. Anisantha are best cultivated soon after harvest, to ensure germination and allow a stale seedbed to be created. Whereas bromus are under-ripe at harvest, so are best left on the soil surface to mature.

Accurate identification of the species therefore allows tailored cultural control, as well as chemical.

For optimum weed control, cultural methods should be used in conjunction with complimentary chemistry, as part of a wider weed management strategy. Herbicides will need to be selected depending on their registration and the active’s ability to control the brome species identified.

UPL offers two graminicides – quizalofop-P-tefuryl (Panarex®) and clethodim (Centurion® Max). Although there is no label claim for bromes for products containing these actives, there is known efficacy. However, the levels of control are not consistent across brome species, so UPL is working with ADAS to aide decision making.

Results from early collaborative work have demonstrated that the anisantha species, such as sterile brome, requires a higher dose of graminicide than the bromus species, eg soft and rye brome, and that for clethodim, the current 1L/ha label dose rate with 120g of active ingredient is not always sufficient.

Conversely, bromes are known to be very well controlled with relatively low doses of Fops, especially quizalofop-P-tefuryl. This means for oilseed rape this autumn, there is real value in an early Fop application, not only for the removal of volunteers prior to clethodim, but also for brome control.

Maximising active ingredient entry into the weed is critical for all graminicides and will improve efficacy. Water conditioner can help this by reducing the lock-up of active in harder waters, so is always recommended for use with clethodim to optimise the full 120g of active. It is also beneficial to include it with applications of quizalofop-P-tefuryl.

Finally, it is important to use products with alternative modes of action as part of a wider resistance management programme. Not just the approach for blackgrass, the same ethos should be applied to brome control. An example is in oilseed rape where clethodim can be followed by propyzamide.

Other products with known activity on bromes through the rotation include ethofumesate in sugar beet (Efeckt®) and wheat (Xerton®), and flufenacet/diflufenican (Reliance®) in cereals.

UPL is continuing to invest in graminicides, with some exciting opportunities on the horizon which will allow improved control of bromes. in broad-leaved crops