The profusion of poppies seen in crops just harvested will provide a challenge to advisors this autumn, particularly without the help of the standard treatment, trifluralin. But effective solutions are available and need to be implemented carefully, especially when this weed has the ability to produce very high levels of seed and has extraordinarily long seed longevity.
"Understanding the biology of a weed species enables better management of that weed. In the newly published HGCA/BASF Encyclopaedia of Arable Weeds, common poppy throws up some real challenges. For example one poppy plant can produce up to twenty thousand seeds. Those seeds have longevity of up to one hundred years, which explains why this weed is found in profusion all over the country every year," says Clare Tucker, Agronomy Team Manager for BASF.
She also points out that poppies germinate mainly in the autumn starting in September through to November, with a smaller less significant flush in the spring from March to April. "Poppies are also very competitive weeds with a Competitive Index on a par with black-grass and mayweed. You need just 12.5 weeds per metre² to suffer a 5% yield loss."
According to Clare, with such high seed numbers, extremely long seed survival, high competitiveness and a strong autumn flush, an early start to poppy control is vital. "But you also need persistent control. This is why a split dose programme of a residual herbicide, such as Shadow, offers a useful alternative to any trifluralin-based treatments. In one series of trials a split dose of Shadow, pre-emergence application followed by a post-emergence one, gave over 95% control of poppy."
This experience is confirmed by Chris Bean, Technical Manager for UAP. "Farmers are crying out for a replacement treatment for poppy, now that trifluralin has gone. The very scenic but rather embarrassing red poppy fields, particularly on the lighter chalky soils, are testament to the weeds competitive nature. In UAP trials a pre-emergence application of 1.5 l/ha of Shadow followed by 1 litre/ha post-emergence at the 1 to 2 leaf stage gave control in the order of 95-100%. The addition of the dimethenamid-p in Shadow certainly improved persistence."
Clare Tucker explains that the active quinmerac, which is in Shadow as well as Novall, adds good activity and long-lasting control of both poppies and cleavers. "When you add in dimethenamid-p, as in Shadow, this strengthens the activity on these difficult and competitive weeds even further. And of course with the three actives in Shadow you are getting the widest weed spectrum of all."
Will Reyer, Oilseed Rape Product Manager for BASF, reports that, in a recent survey of the leading agronomists in the UK covering around 50,000 hectares of winter oilseed rape, poppies were the second most widespread weed in the crop after black-grass. "Asked what the top weeds in winter oilseed rape were 74% of the agronomists cited black-grass and 61% said poppy, followed by cleavers (57%) and charlock (48%). Not surprisingly nearly 75% of all advisors said that the loss of trifluralin in oilseed rape would be a significant issue for them. Solutions such as Shadow and Novall will be the modern way of tackling the profusion of poppies that we are likely to suffer."
He warns that correct doses and correct timing are important. "The split dose approach gives the best results, taking out the early flush and offering good, long-lasting activity."
For information please contact Will Reyer of BASF on 0161 488 5490
Background Notes
1) HGCA/BASF Encyclopaedia of Arable Weeds
ADAS and BASF have published a new Encyclopaedia of Arable weed as a useful and practical reference for all arable farmers and agronomists in their battle to control weeds. Farmers and agronomists can get their personal copy of the Encyclopaedia of Arable Weeds either via BASF’s web site AgriCentre on www.agricentre.basf.co.uk or via HGCA.
2) Shadow contains 200 g/l of dimethenamid-p, 200 g/l of metazachlor and 100 g/l of quinmerac, formulated as a suspo-emulsion, packed in a 10 litre pack. It is recommended in Winter Oilseed Rape for the control of broad-leaved weeds plus some grass-weeds including Annual Meadow-grass and Black-grass. Shadow is a residual and contact acting herbicide. It is recommended pre- and early post-emergence at dose rates of 2.0-2.5 l/ha in a minimum of 100 litres of water. The latest time of application is before 7 true leaves (GS17). It is subject to LERAP B.