Correct Application and Hints for Success
Mechanical barriers are still the best protection against bird damage in the vineyard. Nets applied can be the traditional covering drape net or the more recent Fruit Zone Netting (FZN). Advantages and disadvantages were discussed in an article published last year in Grape Grower and Winemaker and a transcript can be viewed here.
Less netting is required for FZN reducing ultimate impact on the environment and the hip pocket. Coloured nets are also becoming available and this will be invaluable in regions where visual pollution is an issue. FZN also lets foliage protrude from the top minimising the visual impact of netting. With the Netline Netting Machine being within the price range of smaller vignerons, machines can be dedicated to a vineyard or region, reducing the chance of disease spread. There is also no requirement for ancillary items such as post caps and repair kits for large tears. Once applied FZN can withstand strong winds, allow row access and cases less shading effect to the vine.
Hints for Successful Use of Fruit Zone Netting
Many vineyards use a vertical shoot positioning (VSP) system to give partial shade to grape bunches and improve the quality of the grapes and wine. FZN suits VSP trellising systems.
Traditional FZN has been applied by clipping the edges to a dripper wire below and a foliage wire above the fruiting region of the vine. Better cover with less potential stretching of the net is obtained with a dedicated wire below the fruiting zone (X) and another above (Y) which is positioned below the ultimate foliage wire position (Z). This allows more ballooning of the netting making it harder for birds to attack any peripheral berries.
Diagram 1 showing Netline Netting application to wires.
Simple bread clips are still the cheapest and easiest to apply clipping mode. They can be supplied in boxes of 40,000 for around $250. A team of “clippers” is best made up of 2 advance workers moving rapidly behind the netting machine while it is unwinding at walking pace, with a follow up team of 2 or 3 “clippers” securing the net. A couple of hectares a day of netting application is well within reach of such a team.
Removal requires the Netline Machine being pulled behind a tractor or ATV. No hydraulics are required therefore not tying up a second tractor. Approximately one hectare of netting per hour can be removed under optimal conditions. Only the driver is required for removal of the nets.
Diagram 2 showing row application.
It is best to apply the FZN so that it can be rewound without any contortion at the end of the rows. There is no need to cut the nets.
This pattern makes for untroubled removal, keeping the vines to the same side of the machine. The machine can handle sharp turns, especially if pulled by an ATV. Removal of the netting is the reverse of the application.
When netting is being removed, the UV degraded clips snap when the net comes under tension. It is advisable to wear eye protection to guard against flying clips.
With tight knit high quality netting, there is little penetrative growth of shoots through the netting. If this occurs, the retrieval arm on the Netline machine usually removes such problems.
Although round bale netting can be applied it is false economy. Small birds can penetrate the large weave and the netting tears relatively easily. Round bale netting may last for 2 years or even 3 if careful.
Quality netting is available which is guaranteed UV protected for 10 years, with string woven net leading to much less chance of tearing and vastly superior bird exclusion. Coloured netting is becoming available. This does not necessarily deter the birds, but may be aesthetically more desirable. One kilometre of higher quality netting can be comfortably rewound onto the removable Netline spool.
Thos voracious birds will still find a way in occasionally, but with FZN are restricted to a small area say one or two vines. Drape nets act like a large aviary, and you need a dog to chase the birds from under this system.
With FZN it benefits to pay more attention to clipping on outside rows and near trees. This is where the majority of bird strike originates.
Successful netting will save grapes and preserve quality of 95% of grapes in heavily populated avian territories. Netting is very successful in areas of less bird density.
Graeme Bertuch has vineyards in a 10/10 bird density region. No nets – No grapes.