Herbicides spatially variable applications

Spatially variable applications of herbicide can be made in fallow or widely spaced row-crops, such as maize or soya beans, by using spectral reflectance type detectors to determine the presence of weeds, and to actuate a spray application system directly. This approach has been developed commercially both in Australia (Felton, 1995), and in the USA, and considerable savings in herbicide use have been demonstrated - see also Chapter 3. The same approach has recently been developed in Europe for use in amenity areas, where the presence of weeds in pavements and gravel paths can be detected by systems working on spectral characteristic criteria. 

Much of the field trials work with spatially variable (patch) spraying systems has used herbicides, and has shown that typically some 50% of the chemical needed for grass weed control in cereal crops can be saved. Other weed species are also known to be patchy (cleavers and thistles), and therefore overall estimated savings in herbicide use are commonly around 25%. Research work is currently examining the scope for the spatially variable application of... 

SPATIALLY VARIABLE HERBICIDE APPLICATION Map of A. myosuroides density... 

Miller, P.C.H., Paice, M.E.R. and Ganderton, A. (1997) Methods of controlling sprayer output for spatially variable herbicide application. Proceedings, Brighton Crop Protection Conference - Weeds, 641-644. 

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