Arable
Simple solutions for spring weed control Use SUs to their strengths in conjunction with alternative partner products, growers are advised.
The question of efficacy in a spring herbicide programme is often defined by the ability of the active ingredients to deliver maximum control in the most cost-effective way. Sulfonyl-ureas, (SUs) have been the mainstay of agronomists’ recommendations for 30 years and with pressure on growers to protect existing chemistry through strategic stacking of active ingredients, sometimes the more simple and uncomplicated mixes, used in the right combination and at the right timing can prove very effective. That’s the message from independent AICC crop consultant, Tod Hunnisett, who advises arable growers on all aspects of crop management from Dorset to the
eastern tip of Kent. With a significant area (600ha) of spring barley to look after, Mr Hunnisett, who is also part of the Crop Advisors buying group, stresses the importance of adapting spring broad-leaved weed programmes to cope with a wide spectrum of species and using SUs to their strengths in conjunction with alternative partner products. With groundsel, cleavers and polygonum species the main competition, a well timed SU is nearly always appropriate. “I’ve been using them for well over 20 years now,” explains Mr Hunnisett. “They are still incredibly effective, but only if properly managed and applied prescriptively and of course we have
the benefit of many years experience.” For general control in spring barley he is in favour of a mixture of Ally Max SX (143g/kg metsulfuron-methyl + 143g/kg tribenuron-methyl) plus bromoxynil, which means delivering a broad spectrum hit with the ability to apply confidently up to GS 29–30 without compromising control of larger and rapidly growing weeds. “It’s about simplicity, but also flexibility,” he continues. “At that growth stage, I can combine a substantial herbicide element with a fungicide and trace elements if I need to. I’m always conscious of clients’ costs and the need to economise. By keeping unnecessary spraying to a minimum, we can focus on several things at once, but still with the ability to complete the task at each level. The SU element of the tank mix is integral to that and I try to maximise the use of each sprayer pass.”
Cleavers control Adding fluroxypyr to the SU also provides Mr Hunnisett with an enhanced level of cleavers control, but only when temperatures are adequate for its best use. “The tribenuron element is brilliant
on groundsel, the metsulfuron will pick up mayweed, charlock and volunteer rape and then it’s a case of adding the HBN for the polygonums and fluroxypyr for the cleavers and chickweed,” he adds. For heavier cleaver populations, fumitory and poppies, 40g/kg metsulfuron-methyl + 400g/kg thifensulfuron-methyl (Harmony M SX) raises the efficacy further on those particular weeds. “Although it can be costly to use at full rate, even a reduced rate, applied with the right partner and at the correct timing, can do a very satisfactory job,” he says. Mr Hunnisett also points out that SUs still play a significant role in winter wheat crops where late germinating creeping thistle and sow thistle following temporary grassland, can be a problem. “Even if we’ve applied a spring SU for black-grass, aggressive weeds such as thistle can appear at a relatively later stage. Using a product like Ally Max SX right up to T2 is ideal in this situation and is perfectly OK to use in sequence, as it just counts as one SU. I’ve never noticed any following crop effect and again it can often be used with a partner product, such as fluroxypyr, which broadens the spectrum if needed,” he concludes. ■
A timely boost for weed control in maize Last year’s launch of a new contact herbicide for maize gave Agrovista agronomist Bob Smart (right) a timely opportunity to address many of the historical weed problems he had encountered since taking on the role of working with farmers in Leicestershire, Warwickshire and Staffordshire in 2013. “I currently advise on just over 1,000ha of maize dealing with both livestock farms growing wholecrop maize for dairy and beef rations, and arable farms producing whole crop and grain maize for anaerobic digestion (AD) plants,” commented Mr Smart. “Both require good advice on effective weed control to maximise yields,” he added. Covering the territory for five years has given him an accurate picture of the weed profile and crop challenges his customers face but he had always felt that a boost was required in the
tank mix to improve the speed of knockdown in emerging weeds following a pre-em spray. “Both cranesbill and black nightshade have always been key problems in my area and cranesbill, in particular, is readily capable of swamping any developing maize crop if you do not get on top of it early enough.” In 2017 he was able to add the new contact herbicide Gyo (pyridate), from Belchim Crop Protection, to the post-emergence tank mix for the first time, replacing terbuthylazine which will not be re-registered after this year. “Following last year’s trials it was clear that speed of knockdown on emerging weeds had improved significantly and the new product had held up well against a broader weed spectrum,” he confirmed. When the maize was at 2–4 leaves, Mr Smart applied Gyo at 0.5-litres/ ha in the tank mix, partnering with Elumis (mesotrione + nicosulfuron),
keeping water volumes at 200-litres/ ha to ensure good crop coverage. “For application I recommend using alternated forward and down flat fan nozzles or, for even better coverage, a twin cap with a VP80 nozzle forward facing and a 3D Defy nozzle facing straight down which produces finer droplets, improving penetration of the spray into the crop canopy to reach surrounding weeds more effectively,” he suggests. Gyo has no following crop restrictions, important for farmers who are growing maize within a wider crop rotation, and Mr Smart was impressed with the level of crop safety that it offers. “Crop safety is critical and it’s clear from the product’s 15-year registration – the longest term allowed under EU regulations – that Gyo is very much a long term option for growers and advisers.” For 2018 he intends to increase his use of the new herbicide and try out different application rates under a wide variety of growing conditions
to learn more about the product’s effectiveness. “Although using Gyo at 0.5-litres/ ha in the tank mix delivered an effective level of control last year, I know I have the option to increase the rate to 0.75-litres/ha when tackling larger weeds. Now that I know it works I need to find out how best to maximise results in my own programmes under different conditions,” he concluded. ■
Gyo is a new contact herbicide for use on maize.
30 www.farmersguide.co.uk May 2018
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