Weed control in cereal crops has become one of the greatest challenges for the agricultural sector not only in the UK but worldwide. In the UK Blackgrass is a major grass weed responsible for yield losses in a wide range of crop types.
Without new interventions the growth of herbicide resistance in Blackgrass threatens the future viability of almost all autumn sown crops; growers are having to spend more and more on the cost of control.
Spring herbicide applications are the last opportunity to kill or maim any surviving Blackgrass plants that have made it past the autumn residuals.
Over the last 10 years a number of strains of Blackgrass have developed which are able to overcome the effects of the most popular spring applied herbicide, resistance has developed.
Unfortunately many within the agricultural industry do little to encourage proactive management of individual weed species to prevent or delay the selection for herbicide resistance. This leads farmers to adopt integrated weed management practices only after herbicide resistance has evolved and not before.
For general discussion there are two types of resistance, target and non-target site.
Target site resistance occurs through changes within proteins that are targeted by the applied herbicide. The consequence of this is a reduction in the effectiveness of the herbicide at their site of activity. This can often lead to “zero kill” of the targeted weed.
Non-target site resistance (or enhanced metabolic resistance) describes the process by which plants are able to detoxify the herbicide before it is able to kill the weed. Such plants show a range of symptoms from near complete kill to a period of stunted or slow growth after which they appear to "shrug off" the chemical and once more resume active growth.
Catchy title. Human-mediated environmental management, in short it could mean we as humans fiddle with the natural order of things - not always to our own advantage!