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

to investigate the problem and develop a management strategy (R Hewer 2008, pers. comm.).
A report on the project can be found on the Australian Lychee Growers Association’s website
at: www.australianlychee.com.au/items/54/Longicorn%20Beetle.pdf
Orchard netting
Two types of netting systems are commonly used by growers:
1. Full canopy netting—The net is held permanently by a rigid structure of poles and tensioned
cables over the entire orchard.
2. Tunnel netting—A series of light frames connected by wires are erected at intervals along the row
to support the net and hold it away from the tree. The nets are placed over the frame only when
the fruit approaches maturity and are taken down after harvest.
Some points to note are:
•
•
•
•
•
•
•
Orchard netting provides a physical barrier between the pest and the crop, giving a high level of
protection that is reliable from season to season at all levels of pest pressure.
Provided a suitable mesh size is chosen, the net can protect against a wide range of potential
problem animals (such as flying foxes, birds, fruitpiercing moths, fruitspotting bugs, macadamia
nut borers, fruit flies, wallabies, hares and possums). Appropriate netting can also protect
orchards from wind and hail damage.
Cost is the major hurdle with netting. Netting an orchard can cost from $17 000 to $72 000 per
hectare depending on the system and type of net used.
Difficulties associated with topography, orchard layout and tree size can make orchard netting
construction impractical or lead to higher construction costs that make it uneconomical.
There is a risk of storm or fire damage to the nets.
Depending on crop, location and management netting can beneficially change the orchard
microclimate resulting in higher quality fruit production from the netted orchard. There is also a
possibility that microclimate changes under a netted orchard will result in production of poorer
quality, less valuable fruit.
Netting is generally regarded as an environmentally friendly and socially responsible approach to
the problem of vertebrate pest control.
The different characteristics of tunnel and full canopy netting are compared in Table 2. This information
may help you to identify the most suitable system for your situation.
Table 2. A comparison of tunnel and canopy netting systems
Factor Full canopy netting Tunnel netting
Capital cost High cost, $23 000–72 000 per hectare. Moderate cost, from $17 000 per hectare.
Support
structure
Net quality and
cost
Needs to be strong and durable and is
therefore relatively expensive.
Nets are permanently exposed to the elements
so good quality, more expensive nets need to
be used.
Quantity of net Nets cover only the top and sides of the whole
orchard, reducing the area of net needed per
tree.
Recurrent costs No recurrent costs putting out and recovering
the nets.
Maintenance Repairs to net and structure will be required
from time to time, depending on quality of
materials used and weather events.
8
To net or not to net
Can be made from lightweight and
relatively low-cost materials.
Nets are on the trees for only +/–
2 months per year, so cheap light
weight nets can be used.
Nets cover the top and the two sides of
each tree row, increasing the area of net
needed per tree.
The cost of putting out and recovering the
nets each season is significant over the
life of the orchard.
Frames need to be smooth to minimise
net damage during application and
removal. Store nets in vermin-proof
containers.