Wild Oats, Ryegrass and Brome Control
Increasing prevalence of grassweeds in cereals can be in part be attributed to a shift in farming practice including:
Consequently soil seed banks are replenished and the window for control by non-selective pre-emergence herbicides is reduced.
Wild Oats Identification - Seedlings have an anti-clockwise twist, hairs on the leaf margins, a membranous ligule and no auricles. Mature plants grow up to 150 cm tall. The stem is round, the leaves are hairy. There are no auricles, and the ligule is tall and rounded. The seed head is an open panicle, and the spikelets usually contain 2-3 florets. The panicle may contain up to 250 awned seeds, which range in colour all the way from black to white. In Avena fatua the florets fall as single seeds, whereas in A. ludoviciana the seeds fall as a united floret. The awn of A. fatua is 25-40 mm long and inserted about half way up the lemma. In A. ludoviciana it is 35-60 mm and inserted below midway on the lemma.
The seedhead is a flattened spike with spikelets arranged alternately on opposite sides of the stem. The spikelets are awned and stalkless and have their rounded face next to the stem. (The spikes of couch are similar but have the flattened face of the spikelets next to the stem.)
Perennial Ryegrass Identification - Leaves hairless with glossy underside, and tend to be narrower than Italian ryegrass. When the stem is cut horizontally the leaves can be seen to be folded in the sheath. The stems are flattened (Italian ryegrass rounded). Auricles are present and hairless. The seedhead looks like Italian ryegrass except that there are no awns on the spikelets.
Brome Identification - 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 is 2-4 mm long and toothed, in great brome it is 2-6 mm long, rounded and jagged. In meadow brome it is 1-4mm long, flat, and toothed; In soft brome it is short –up to 2.5 mm, rounded and jagged, while in rye brome it is only 1-2 mm, flat and toothed.
Seedling emergence is dependant on soil moisture and temperature but is also affected by soil cultivation and seed dormancy. Germination flushes occur in the autumn and again in the spring at temperatures in the range of 10-26°C. Deep burial of the seed by ploughing induces dormancy. Seeds can remain viable for up to 13 years, but few remain viable for more than 3 years. The seedbank half-life is about 6 months. At weed densities up to 40 plants/m2 each plant can produce about 225 seeds, but at densities over 50/m2 this can fall to below 50. The net result is that in crops which are untreated, seed production can range from 1,000 to 10,000/m2.
Italian ryegrass can be annual or biennial, 30-90 cm high. It can be very well tillered or not depending on crop competition, but is very aggressive in its spring growth pattern. Flowering occurs in May-August and seed is shed before harvest and can persist in the soil for up to seven years.
Perennial ryegrass is a competitive weed, but less so than Italian ryegrass. As the name indicates it is a perennial plant 30-60 cm tall and will tiller as much as conditions allow.
Anisantha bromes (sterile, great brome) germinated 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.
Broadway Star - Broadway Star offers excellent control of ryegrass, brome species and wild oats in winter wheat, rye and triticale in non-blackgrass areas. It also offers cross-spectrum weed control against a number of key broad-leaved weeds including cleavers, speedwells, groundsel, charlock, pansy and cranesbill.
Where blackgrass is the driver grassweed then use Unite or Broadway Sunrise.
Unite - Unite is the widest spectrum graminicide in the UK controlling key grassweed species in winter wheat including blackgrass, ryegrass, brome species and wild oats. It is also active against loose silky bent, canary grass, couch (from seed) and meadow grass. Unite can be applied to the crop from GS-11 to GS-30, offering a wide window for both autumn and spring applications. Unite can be mixed with a residual herbicide to offer comprehensive treatment of grassweed populations.
Broadway Sunrise - Broadway Sunrise offers excellent control of key grassweed species including blackgrass, ryegrass, brome species and wild oats in winter wheat, rye and triticale. It also offers cross-spectrum weed control against a number of key broad-leaved weeds. The combination of pyroxsulam and pendimethalin in Broadway Sunrise gives both contact and residual activity against target weeds.