Fruit Zone Netting
Many methods have been and are in use to deter birds, from scare crows. trained falcons, noise devices, plastic hawks, shimmering visuals to shooting. Some of these methods are indeed novel, while others border on cruel, and with today’s sensitivities not appropriate!
The most benign method would seem to be one that can physically separate the birds from their target… the grape!
Sensitivity of any given area to birds depends on numerous factors. Many of the vineyards most at risk from birds are near forests or woodland areas. They are often isolated with few other vineyards close by. They are more prone to bird attack in dry years when other food sources are scarce. In these regions, nets are the most appropriate deterrent.
In this article we will look at the relative benefits and negatives of fruit zone netting and the more traditional drape netting. The fruit zone netting is of similar quality to the drape netting [but cheaper alternatives are available particularly for the fruit zone netting.]
Gale Pacific provide both drape [multivine] and EZ10 Vineside or fruit zone netting and we will use these for this comparison. The Multivine is 18m x 300m and the EZ10 is 1.2m X 500m. These are the most commonly used netting sizes.
The requirements to cover one hectare of vines are 3.5 rolls of Multivine or 16 rolls of EZ10. The recommended retail price is 28 cents per square meter for the Multivine and 33 cents per square meter for the EZ10.
The netting is applied by a Netline fruit zone netting applicator in the case of the side net, and a commercial hydraulic drape net applicator.
|Rolls of net per hectare||16||3.5|
|Net Area per hectare||9,600 sq m||18,900 sq m|
|Price per hectare [rrp]||$3168||$5292|
|Manpower to apply||+++||++++|
|Manpower to remove||+||++++|
|Work Care Issues [bale weight 25 kg vs 500 kg]||+||+++|
|Vineyard soil compaction||++||+++|
|Suit small operator||yes||no|
|Driver only removal||yes||no|
|Towable on road||yes||no|
|Multiple vineyard passes||yes||no|
|Most suitable trellising||VSP||any|
|Row access after application||yes||yes [with difficulty]|
|Ancillary items [post caps, pegs]||no||yes|
|MOG in bins||occasional clip||plastic post tops if mechanical harvest|
|Need to clean canes from vineyard||no||yes|
|Wind stable||yes||not always|
|Vine effect||minimal||weight effect|
|Hedge after application||yes||no|
|Cheaper alternatives for netting||yes||maybe|
|Potential other applications||windbreaks, wire spinning||fruit trees|
|Machine cost||$8000 + GST||approx $13,000|
The susceptibility of the grapes to birds in both cases depends on proper securement of the net. Clipping for the side net has to be tighter in areas of high bird risk, eg near trees.
Drape net has to be secured at the sides to prevent wind shifting the net. This is particularly a risk when the wind blows at right angles to the net.
Kangaroos and emus have been known to cause rents in drape nets. This is not a problem with fruit zone netting.
Fruit zone netting allows easy access to vine rows so that maintenance, spraying and if necessary, cultivation can be performed before vintage.
Fruit Zone Netting offers alternatives for net pricing. Round bale net can be used and this would cost under $1000/ hectare and would last 2-4 seasons. Polytape Net from Gale Pacific is a superior alternative and would cost ----- . This should last 3-5 seasons.
The EZ10 is guaranteed UV stable for 10 years, while the Multivine has a 15 year UV guarantee.
OH&S issues have been alluded to in the table. The main issues to consider would be the weight of the net and effort required to apply and remove and the risk of contacting overhead structures.
With fruit zone netting and using the Netline machine the nets can be removed ahead of the pickers at harvest time.
Fruit zone netting is less demanding on the vineyard workforce and has been observed to be a lot more acceptable than the laborious drape nets. This means happier workers!
Australia has traditionally used cover or drape nets perhaps because of the numbers of larger vineyards and the availability of an effective machine to apply these large nets.
In New Zealand both drape nets and fruit zone netting have been used. Machines to apply fruit zone netting have been evolving, but have relied on hydraulic drivers, which tie up a tractor to apply and remove the net. The Netline Netting Machine does not require hydraulics to retrieve the net, and is pulled rather than sitting on front of the tractor.
This means that workers who apply the net are not tempted to work alongside the tractor wheels. The Netline Netting Machine can retrieve netting up to 4 times faster than hydraulic driven side netting machines. [under optimal conditions one + hectare per hour]. It can be pulled by an ATV, a Gator or even a ride on mower.
Both fruit zone netting and drape or cover netting have a place in the management of bird strike. Drape netting is particularly good where large areas have to be covered as it is quicker to apply, suiting large organizations which have a ready workforce. Fruit zone netting is an economic and practical option for the smaller vineyard or for peripheral netting in larger vineyards.