Don’t give black-grass a break With the key timing for spring black-grass control in wheat imminent, growers are warned not to be complacent following an autumn where good levels of control were seen from preemergence programmes. Dominic Kilburn writes. Significant levels of black-grass will still be found in some fields this spring and the advice is to focus on the overall grass weed control programme made at the start of the season – and stick with it. That was the message from Bayer campaign manager for herbicides, Ben Coombs, speaking recently at the company’s grass weed screen trials site at Chishill, Cambridgeshire. “The general perception of last autumn was that seedbeds were good, there was sufficient moisture and a lot of late drilling – all ideal situations for good black-grass control – and it’s anticipated that pre-ems worked well,” commented Mr Coombs. “But there can still be significant levels of black-grass in fields now and I urge growers to get out there and look to check where the blackgrass has crept back in. “The concept that you can reliably get all the required levels of control from pre-emergence treatments only, is not feasible,” he stressed. “At the spring timing, you need to get that extra control of blackgrass to help reduce the final seed return,” he added.
Herbicide performance Pre-emergence plots at Bayer’s Chishill weed screen looked at Liberator (diflufenican + flufenacet) on its own, and as a base with additional partners including
Avadex Factor (tri-allate) and Defy (prosulfocarb) at 2-litres/ha, versus key target weeds. “Following a pre-em of Liberator, the difficult black-grass strains are starting to come through at this stage but you would still anticipate up to 80 per cent control on farm when applied on a later drilled wheat crop,” said Mr Coombs. “Tri-allate is a useful addition to pre-em treatments and prosulfocarb is a very good option to go with Liberator, but it does come with the risk of too many actives potentially hurting the crop. “Crop competition is important in holding weeds back, so there is the option of coming back later with another 0.3-litre/ha rate of Liberator rather than loading it all up front,” he explained.
New product Bayer development manager, Dr Gordon Anderson-Taylor said that in plots showing a delay in application of Liberator as a pre-em (14th November – just over one month after sowing), efficacy drops off, emphasising the need to get pre-em treatments on at the pre-em timing. However, he added that the company was hopeful for the registration of a new pre-emergence product. As yet unnamed, he said that the new product, which is based on Liberator, with the addition of metribuzin (a potato herbicide) adds 10 per cent extra control of black-
Bayer campaign manager for herbicides Ben Coombs (left), and the company’s development manager, Dr Gordon Anderson-Taylor.
grass over Liberator, while it also provides some control of other grass weeds and important broad-leaved weeds such as cranesbill. With the addition of either triallate or prosulfocarb, then control levels would be further increased, he pointed out. “The new product has the really useful benefit of not suffering from a delayed timing as much as other preem treatments,” noted Dr AndersonTaylor. “So if pre-emergence timing is delayed, it will hold on to its efficacy better than Liberator on its own and there won’t be so much control lost,” he added. With several herbicide development projects on-going, Dr Anderson-Taylor hinted at another product in the Bayer pre-emergence pipeline, albeit unlikely to be available until 2021. “Used in the same way as Liberator, and with a new active for cereal growers, it looks like it will be another step up from the Liberator +
metribuzin product and become the new standard for pre-em grass weed control,” he said.
Post-em control With a reference to post-em grass weed control for the weeks ahead, Ben Coombs suggested that the earlier that applications of the company’s Monolith (mesosulfuron + propoxycarbazone) or Atlantis (mesosulfuron + iodosulfuron) postem treatments could be applied, the better, and preferably ahead of fungicide applications. “Even on resistant strains Atlantis WG is still taking out, on average, about 50 per cent of the black-grass which is present in the field at the time of application. Monolith will boost this level of control by a further 10 per cent so, where black-grass is the challenge, Liberator in a mix at pre-em, followed by Monolith (up to growth stage 32) will give growers the best chance of getting up to where they need to be in terms of control,” said Mr Coombs. ■
Top tips to manage fungicide resistance in septoria
Top management tips to help slow fungicide resistance in septoria have been issued as part of the Fungicide Futures initiative.
Answering 12 frequently asked questions on septoria management, the tips will help people strike a balance between good control within the season and efficacy protection across seasons, says AHDB. The information has been issued following a debate at the 2017 AHDB Agronomists’ Conference, which concluded that low resistance risk fungicide programmes must be adopted universally to prolong the efficacy of cereal chemistry. Paul Gosling, who manages crop disease research at AHDB, said:
“Everyone needs to take collective responsibility to manage fungicide resistance threats. “To bring extra clarity to the action required, we’ve worked with the Fungicide Resistance Action Group to cut through the science and provide easy-to-digest information that can be used straightaway.” The ‘Top Tips’ and information on Fungicide Futures, a joint initiative
between AHDB and the Fungicide Resistance Action Group UK (FRAG), can be found at: www.cereals.ahdb. org.uk/fungicidefutures. ■
Everyone needs to take collective responsibility to manage fungicide resistance threats, growers and agronomists are advised.
March 2018 www.farmersguide.co.uk 21
1-29 ROP Mar.indd 21
Farmers Guide Magazine March 2018 Issue