Marker system use

Some form of field marking is essential if both spraying efficiency and accuracy are to be maintained.  The type of marker selected depends on the sprayer and the environmental requirements.

Boom sprayers

Foam markers have the widest application for broad acre spraying.  A white color is suitable for in-crop and bare fallow.  However, inadequate foam life may be a problem with some systems during the hotter months.  The use of higher operating pressures, higher foam concentrations and larger blobs may improve the foam life.

Silver streak markers are used successfully to spray in-crop and some fallow situations.  Visibility problems have been encountered when used on some winter cereal stubble (for example, barley).

Disc markers mounted on the boom are quite effective.  They give a positive mark in both fallow and young crops but do have limitations in dry soil.  Make sure the disc throws soil away from the swath being sprayed.

Permanent markers and ‘tram-lining’ have proved successful where the topography and machinery allow these systems to be implemented.

Knapsack spraying

Moveable markers are often used when spraying a field with a Knapsack sprayer. It is best to use at least 3 markers in each spray run to avoid over spraying or missing strips in the field.