Bromes in recent years have become more widespread and where they were once confined to the headland, are now being seen across the field, spread by combining and cultivations.
Although it is relatively easy to distinguish bromes from other grass weeds, identifying individual brome species is difficult, particularly in the vegetative stage. Bromes have a rounded stem and hairy leaves and there are no auricles. The ligule in sterile brome (Anisantha sterilis) is 2-4 mm long and toothed, in great brome (Anisantha diandra) it is 2-6 mm long, rounded and jagged. In meadow brome (Bromus commutatus) it is 1-4mm long, flat, and toothed; In soft brome (Bromus hordaceus) it is short –up to 2.5 mm, rounded and jagged, while in rye brome (Bromus secalinus) it is only 1-2 mm, flat and toothed.
For a masterclass in how to distinguish between the different brome species, watch this video here.
This “Identification of Brome Grasses” leaflet by Rothamsted Research and Dow AgroSciences provides excellent guidance on brome identification.
Brome species are most commonly confined to headlands or to patches within fields. Their relative competitiveness is roughly equal to ryegrass, slightly less than wild oats, but twice as competitive as blackgrass on a plant for plant basis.
Anisantha bromes (sterile, great brome) germinate in the autumn and require vernalisation to flower. They germinate in the dark, and exposure to light induces dormancy. Seed can remain viable for 2 years, so if ploughing brings old seed to the surface it can become a problem in the following crop.
Serrafalcus bromes (meadow, soft, and rye brome) differ in that the seed needs light and also a period of maturation to germinate. For this reason cultivations after harvest should be delayed for a month to prevent inducing dormancy, after which seeds can remain viable for 7-10 years.