BENEFITS OF CROP ROTATION

Grass Weed Control

Grass weeds such as Wild Oats, Sterile Brome and Canary Grass are very visible this year. Teagasc has also confirmed the presence of Black grass in areas where this weed was previously unknown. Growers should assess fields for grass weed control, taking note of any unusual grass weeds and seek help to identify and put in place an appropriate management strategy.

Grass Weed Quick Management Guide

WILD OATS STERILE BROME CANARY GRASS BLACK GRASS

DISTRIBUTION (IRL) Widespread Widespread Widespread at low levels, locally very problematic Very localised at very low levels

GROWTH HABIT

Annual Annual Annual Annual

MAIN GERMINATION PERIOD

SEED SURVIVAL IN GRASS LEYS

Spring (some in autumn)

10-20 years

Autumn (some in spring)

2 years Spring (some in autumn)

3 years (limited results) Autumn

3 years

GERMINATION DEPTH

15 cm High dormancy 15cm Low dormancy 15 cm High dormancy 6 cm

IRISH CERTIFIED SEED (C1)

Zero tolerance Zero tolerance Zero tolerance Zero tolerance

HERBICIDE OPTIONS Good in wheat and barley and non-cereals Good in wheat and non-cereals, poor in barley

Good in wheat and barley and non-cereals Good in wheat and noncereals, poor in barley

HERBICIDE RESISTANCE STATUS

Resistance common in UK, suspected in IRL Not problematic Not problematic Common in UK, unknown in IRL

EFFECTIVENESS OF STALE SEED BEDS AND SPRING CROPPING

Limited due to dormancy ability Extremely effective Limited as spring germinator Extremely effective

HAND ROGUEING

Effective at low populations, replaces herbicides on some farms

Limited to initial infestations, easy to see in crop, seeds shed before harvest

Limited to initial infestations, difficult to see in crop, seed remain in heads until harvest

Limited to initial infestations, seeds shed before harvest

Colour Coding

Green= Very helpful characteristic for management options Brown = Somewhat helpful characteristic for management options Red = Restrictive characteristic for management options

Grass Weed Identification

Brome

Brome in Ireland falls into two main categories. Anisantha bromes include sterile brome and great brome. Sterile brome is the most common of the bromes in the Republic of Ireland, but it is worth noting that there is a significant great brome burden in the north of the country. The other, slightly less common brome species are known as the Serrafalcus bromes. These include meadow brome, soft brome and rye brome. Different post-harvest treatments apply to the different bromes. Early post-harvest cultivations are advisable if you have a sterile/great brome problem, but not for the serrafalcus bromes. Sterile and great brome both have drooping, wedge shaped spikelets, with long spreading awns. Visually, they are quite similar, however, great brome has larger spikelets and the axis of their panicles is hairy, whereas the sterile brome axis is hairless.

Sterile Brome

Soft brome, meadow brome and rye brome are somewhat more difficult to differentiate, but this can be helped with some useful keys. Soft brome and meadow brome have hairy lower leaf sheaths. The spikelets of soft brome are also hairy, whereas the spikelets of meadow brome are not.

The lower leaf sheaths of soft and meadow brome are visibly hairy. Rye brome is more upright than the other bromes. It has a hairless lower leaf sheath in general (not always). Unlike the spikelets of soft and meadow brome, there are small, visible gaps between the seeds in rye brome. Also, if you take a dry, ripe seed and cut it across (cross-section) with a sharp blade, rye brome will have a v-shaped cross-section, whereas soft and meadow brome will have a saucer shape.

Note the gaps between the seeds in the rye brome spikelet when compared with the tight packing of seeds in the soft and meadow brome spikelets above.