HERBICIDE USE IN HIGH DENSITY PLANTING
However, the application of herbicides in high density plantings poses a number of additional problems which do not occur in more conventional low density bush orchards. Some examples of these problems are illustrated.
Many fruit trees develop root suckers which in a high density planting, a multi-row system or a bed system may be difficult to remove mechanically. When spraying weeds with chemical herbicides, inevitably these root suckers will be sprayed at the same time and thus provide a potential source of entry for a translocated foliar acting herbicide.
Experiments with glyphosate and fosamine have shown that care and careful timing of sprays are necessary when spraying suckered trees.
In situations where the foliage of the tree was well separated from the soil surface, then a very wide range of herbicides, including those toxic to the tree if brought into contact with the leaves, could be used. The presence of foliage near to the soil surface is likely to restrict the choice of chemicals and so those showing substantial crop tolerance are likely to become of increasing importance.
The advent of high density plantings is, therefore, likely to require a reappraisal of both the chemical herbicide used in our orchards and the method used to apply them.