To net or not to net - 3rd edition - Department of Primary Industries

Figure 69. Stone fruit under a
3.6 m high canopy net after
pruning
Figure 70. Angle iron welded to
the base of metal support poles
the pronounced ridges (used to maximise soil depth and drainage
in the orchard) made the use of cherry pickers and other machinery
too difficult and dangerous to use when erecting a higher net canopy
(Figure 69).
The posts and wire grid are on a 20 m x 20 m square layout. Some
sections of the orchard have fencing wire diagonals across the grids
to support the net. The wooden posts have a 150 mm SED and cost
$25 delivered.
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All three types of net keep out FPM but the 20 mm mesh with
double cross-stitch is not quite 100% effective.
Timely post-harvest and summer pruning is needed to
control height under the low net canopy.
Doors are kept open to encourage birds to inhabit the
orchard in the off-season and control some insect pests.
Case study 16—full canopy bird and flying fox netting on
stone fruit
A low-chill stone fruit orchard in northern New South Wales.
Originally a black, 50 mm square mesh net was used but this was
replaced with black, 44 mm or 25 mm square mesh nets because
birds got through the original net. Initially, the net was 4.2 m high
but it had to be raised by 60 cm to give a total height of 4.8 m. The
canopy has been raised by bolting an extra length of timber onto the
top of existing posts. External posts are spaced 10 m apart along
the orchard perimeter and the internal posts are on a 14 m x 20 m
grid. Alternate rows of internal posts are lightweight wooden prop
poles resting on bricks. The other rows are more substantial posts
buried in the ground.
Net and structure are nine years old and still in a serviceable
condition. Eight posts (out of 130) have had to be repaired because
they have rotted at the base. This was done by imbedding a short
post alongside the rotten one, bolting it to the sound part of the old
post and then cutting off the rotten base of the old post.
Case study 17—full canopy bird and flying fox netting on
stone fruit
A low-chill stone fruit orchard in South East Queensland.
Two sizes of net are in use—a 100 mm square mesh net (installed
in 1986) and 50 mm square mesh net (installed in 1995). The net
canopy height is 4 m.
Perimeter poles are wooden with a SED of 200 mm sunk 1.3 m into the ground, internal poles are either
100 mm SED wooden poles sunk into the ground (see front cover) or 40 mm metal posts which simply
rest on ‘T’ pieces of angle iron that have been welded to the bottom (Figure 70). The top of these posts
have piece of polypipe, which has a ‘X’ cut into it wedged into them, the X cuts are slotted onto the wires
that support the net (Figure 71). Poles are on an offset 20 m x 20 m grid. The structure is low-cost and
lightweight, but has lasted 13 years.
• Both flying foxes and birds can get through the 100 mm net but it stops most and is still in use.
Losses under this size of net are estimated at about 5%.
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The 50 mm net is flying fox proof but lorikeets can still get through it.
The iron poles, which rest on the ground, sometimes move when the net lifts in a high wind.
Occasionally, following a storm, the grower spends a few days standing up any fallen posts.
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To net or not to net