Crop Margins (Firebreaks)
Managing crop margins is an ongoing source of frustration for many growers. These areas are prone to erosion, are a source of weeds and are often where herbicide resistance develops. Historically these areas were simply managed with one or two applications of knockdown plus residual herbicide. With increasing development of herbicide resistance and the focus on weed hygiene, management of crop margins has become more complex.
Unfortunately, it is no longer good enough to rely on single or even multiple herbicide applications for weed control on firebreaks. Managing these areas into the future is going to take time and effort. The extra effort and attention to detail required to manage this issue will set the best managers apart from the rest. As with many aspects of life, nothing worthwhile is easy.
Following is a list of strategies that may need to be employed to manage the weeds, herbicide resistance and erosion on crop margins:
Elimination or reduction of crop margins around the farm
Removing fences and farming in blocks significantly reduces the area of crop margins. This will improve farming efficiency and reduce the area exposed to the problems outlined above.
In a full cropping operation this is often a simple decision but in a mixed farming operation it requires more thought.
Utilizing temporary fencing structures
Fences that can be removed for the cropping phase and replaced for the pasture phase have proven successful in many cases. The work required to remove and replace the fence is more than offset by increased farming efficiency, plus the reduction in the abovementioned issues.
Diversity of herbicide applications
Applying every herbicide over the crop margin or firebreak increases the diversity of control measures on those areas. This improves control and slows the development of herbicide resistance.
Increased competition
Weeds thrive on areas with no competition. Having something growing on crop margins to use moisture and nutrients will reduce the prevalence, vigor and seed set of weeds. Possible options include:
Sowing broadleaf crops to the fence then spraying them out at the end of the vegetative phase. This is less practical with wheat, as the firebreak or bare area is essential around a cereal crop.
Sowing pastures to the fence so that there is competition during the pasture phase. This will reduce some of the erosion risk and help reduce the population of weed species.
Reduced fertility
Where crop margins are sown, reducing fertilizer rates will decrease fertility, which in turn will decrease weed vigor.
Hay cutting from the outside lap of cereal crops
It is old school, is time consuming and it is expensive. But IT WORKS!!
Like anything worthwhile, these strategies require effort and attention to detail. Ignoring problems such as these will not make them go away.