Wheat growers across the country need to build as much flexibility into their weed control programmes as possible this season to cope with one of the latest springs in recent memory, not to mention the legacy of last autumn’s particularly poor control of problem weeds like brome.
This is the timely advice from Monsanto Crop Protection stewardship manager, Manda Sansom who runs the company’s technical agronomy hotline.
“Many growers have a major dilemma this spring,” she points out. “Last autumn gave them few opportunities for good stubble weed control and the coldest winter for 30 years has really restricted their late autumn and early spring post-em programmes. So they’re facing challenging weed populations while crops will be racing through their growth stages as temperatures warm up, seriously restricting their herbicide options.
“At the same time, of course, they’re acutely conscious of the need to keep both yellow rust and Septoria at bay as well as being very precise with their PGR applications. They have a very delicate balancing act to perform.”
Manda Sansom stresses that the key to handling this has to be maximum weed control flexibility based on herbicides with the longest spraying windows and broadest tank-mixing capabilities.
“With so little time at your disposal, you’ll probably only be able to rely on one decent, relatively late weed hit this spring,” she advises. “So you’ll need to focus this carefully on the weeds posing the biggest threat while giving the best possible clear out of other species.
“At the same time, you’ll need to choose products with a very wide tank-mixing ability so you have the greatest opportunity to combine them with other herbicides as well as fungicides and PGRs without spraying problems.
“Maximum spraying flexibility will come from a herbicide like sulfosulfuron (Monitor) which can safely and reliably be used right up to flag leaf emergence at GS39 rather than only up to around GS33.
“It also has the advantage of the widest physical and biological tank mix compatibility with fungicides, PGRs, trace elements and other herbicides of any modern SU. And, as well as giving excellent control of most brome species, it has good activity against a wide range of other grass and broad-leaved weeds, including volunteer barley and cleavers.”
Manda Sansom acknowledges that later Monitor applications may not be as effective in reducing immediate weed competition as earlier sprays. She insists, though, that they can be very much better at minimising the viable seed return critical to future success in the battle against the likes of brome and blackgrass.
“Many growers may just have to accept greater early weed competition as an inevitable consequence of this season,” she reasons. “But they certainly don’t have to let this build-up even bigger problems for the next crop in their rotation: at least not if they take full advantage of their key fungicide and PGR spraying opportunities for late season control.”
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