DRAFT
Figure 4. Typical sprayhead configuration for tree, bush and vine crops 4.1.1 Distance from Crop
Each sprayhead must be positioned sufficiently far from the crop to allow the airflow from the fan to disperse the spray droplets over a wide band and to prevent local over- application of foliage close to the atomiser. However, the distance should not be so great that the airflow becomes dissipated or that the spray droplets could be prone to drift in a wind. In general, a distance of 0.5 m (20 inches) to the outer face of the crop is preferred in vines. This distance can be increased to 0.75 m (30 inches) if required.
4.1.2Spacing of Sprayheads
Sprayheads must either be mounted sufficiently close together to produce an even swath without ‘striping’ or should be positioned so as to spray specific rows of crops where the rows are planted far apart and the space between does not require treatment.
For broadacre crops, closely planted vegetables etc, the sprayheads should be mounted on a horizontal boom. Sprayheads should be not more than 1.2 m (4 feet) apart to ensure an even swath.
For field crops planted in widely spread rows or beds and for low bush crops, a horizontal boom can also be used. However, the sprayheads should be positioned either above or between rows or bushes. Where the row spacing varies it may be necessary to allow for adjustment of the position of sprayheads on the boom.
For trees, tall vines, soft fruit etc, the sprayheads will normally be mounted on a vertical frame attached to the sprayer. One sprayhead will cover a vertical distance of 1 m (3 feet 6 inches). The number of sprayheads required will depend upon the height of the bush or tree being sprayed and the density of the foliage. In general, dense foliage will attenuate the airflow from a sprayhead more quickly and hence more units will be required to ensure effective penetration and coverage.
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