A range of techniques can be used to produce maize using less herbicides, as one of ENDURE’s From Science to Field guides explains.
Any maize grower would be proud of the field pictured right as this is a crop that needs help, particularly in its earliest stages, to compete with weeds. But unlike many maize fields in Europe, this one has not been subject to the standard application of herbicides to clear the weeds. Instead this Danish field serves as a shining example of integrated weed management (IWM), a broad term covering many methods that can be combined and applied in various ways to form an IWM strategy.
The photograph was taken by Bo Melander from Denmark’s Aarhus University and leader of ENDURE’s IWM Case Study team and is taken from the cover of a useful four-page guide aimed at agricultural advisors and extension services. Maize Cropping With Less Herbicide is part of ENDURE’s From Science to Field series and highlights a range of techniques that can be used to substantially reduce herbicide use for maize crops (the standard chemical solution in many European regions typically includes two herbicide applications).
These techniques include preparing a stale seedbed (a seedbed prepared in advance, designed to encourage weed seeds to germinate), pre-emergence cultivation, inter-row cultivation, band-spraying and broad-spraying with reduced herbicide doses where appropriate.
The researchers suggest that a stale seedbed followed by pre-emergence cultivation should be used whenever possible as this can lower weed density, delay weed emergence and make those weeds which do emerge easier to remove. They recommend that the soil between maize rows be cultivated, using traditional hoes or rolling cultivators (pictured left), as a standard practice, either to supplement band-spraying or to control weeds that have survived previous actions. Band-spraying, though little used in Europe, can save up to 70% of the herbicides normally used in broad-spraying, the team notes, and could become a significant tool for maize production using less chemicals.
The team also examines the use of reduced herbicide doses when broad-spraying, though careful and regular monitoring of the weed flora is needed as there is a risk of herbicide resistance developing. Reduced doses are not recommended for Mediterranean conditions as they are unlikely to be sufficiently effective.
Finally, the team points out that IWM needs to be part of a wider programme that goes beyond just a single crop. Instead, the researchers suggest, maize growers should consider cover cropping and increasing the diversification of their crop rotations to counteract future weed problems.
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