Close look at United Kingdom weed control problems
The 49th British Crop Production Council (BCPC) Annual Weed Review addressed weed control technology solutions at a time of losing products capable of weed control specific to the United Kingdom.
More than 80 delegates attended the review chaired by Gordon Anderson-Taylor, Ph.D., Bayer CropScience, and held at Peterborough, United Kingdom, on Oct. 24.
“Despite the various regulatory challenges, loss of herbicides and ongoing build-up of resistance to current products the presentations made at this meeting demonstrated a range of innovative approaches being taken to address all of these critical issues,” said Anderson-Taylor. “Weed control remains one of the most important factors to maintain sustainable food supplies and our landscape environment, and is a somewhat neglected area for funded practical research. Both researchers and the industry in general are clearly investigating and in some cases adopting new technological approaches in order to ensure that we can maintain adequate control of weeds in the future.”
Peter Lutman, Rothamsted Research, set the scene by assessing the weather conditions in the United Kingdom affecting farming during the 2011/2012 season. Drought and poor performance from pre-emergence herbicides caused problems with weed control in the autumn. Although the spring started well, a cold, wet April meant early sown crops failed to grow and slugs were abundant. Cool wet weather continuing into June and July affected crop growth and grain set.
Lutman assessed current funded research projects on weeds and weed control. “Only a very few substantial projects are now being carried out, funding is limited, there is no long-term strategy for projects and about 30 percent is short-term work being done by Ph.D. students,” he said. “It is now time for us to consider how we get more strategic funding into weed research.”
The review then considered a completely different approach to weed control in oilseed rape with the recently introduced ‘Clearfield’ Production System. “Here we use high yielding herbicide tolerant hybrid seeds which have the ability to resist certain herbicide modes of action not otherwise used in rape,” explained Jon Williams, BASF. “Rather than a pre-emergence/post-emergence program, this program uses one application of a metazachlor plus imazamox product plus an adjuvant, post-emergence up to growth stage 18.”
“This has great benefits as it shifts the timing of application away from the really busy time on farm, it also plays a key role in good establishment of oilseed rape,” said Williams. “More importantly, it targets emerged weeds and offers excellent control with the broadest weed spectrum, including cruciferous weeds, compared to current herbicide standards. It is critical that the metazachlor plus imazamox product is only used on Clearfield hybrids and it is also important that best practice is adopted in rotational management to minimize seed losses.”
There is concern over the potential risk of water contamination from some key active ingredients for weed control in oilseed rape. Ron Stobart, NIAB TAG, outlined a project that evaluates a new approach using carefully-directed control methods between crop rows. Using simple shielding and guidance systems, plots were treated inter-row with glyphosate using a narrow nozzle. Trials were also done integrating inter-row treatments with an over-row selective application. This delivered excellent weed control between and within the rows with little or no crop damage. “The results have been encouraging and no impact on yield has been seen in our studies,” said Stobart. “We now need to look at width of equipment and speed of application. This is an alternative approach of controlling weeds in oilseed rape which could well be considered for other products used inter-row.”
The bracken weed covers an area of about 1.5 million hectars in the UK. It causes problems not just to agriculture by taking out grazing, but it also obstructs footpaths, harbours ticks and disease and creates a monoculture threatening biodiversity. The bracken’s underground extensive rhizome system is the biggest problem, sending up new fronds.