Mark Chien, Penn State Cooperative Extension
http://pawinegrape.com/
Bird Netting Summary
Alice Wise & Libby Tarleton, Cornell Cooperative Extension of Suffolk CountyAugust, 2012
We have felt that color development definitely draws birds. Many times we have observed panels of reds such as Pinot Noir starting veraison. We come back literally the next day and all the red berries are gone. This has happened several times. We know this damage was inflicted by birds due to the bird activity in the vineyard as well as the presence of pecked fruit.
Aromatic compounds must be important as well. A few years ago, before we understood the need to deploy netting right at veraison, we noticed a single panel of Muscat Ottonel stripped clean. White fruit on either side of it was untouched. This was unusual as the panel is in the middle of the vineyard.
When assessing bird damage, it is important to try to distinguish between bird damage and losses to wildlife. Often the two can be found concurrently. We have observed that raccoons prefer red fruit. In our variety trial, they often walk by Chardonnay to get to Merlot. They also seem to prefer Merlot over Cabernet Sauvignon. Maybe it has to do with aromas and/or phenolic compounds, acids etc. Raccoons tend to rip the nets as they aim to get inside, to strip all the fruit from a given area and to avoid green berries. We sometimes see their muddy footprints on our irrigation tubing (located about 12” under the fruiting wire). Bird depredation is much spottier through the vineyard and is found on the exposed side of clusters. Clusters that stick out or are pressed up against the net are much more vulnerable to birds.
We do feel the PermaNet that Spec Trellising sells reduces bee damage. It does not prevent them from infiltrating the net completely. We have watched bees trying to access fruit through that net, they often can't get through. Last fall, after those tropical storms, we lifted some PermaNet and then left for a few minutes to grab some lugs. We came back and in the space of 10 minutes, the bees absolutely descended on this poor panel of Merlot.
Alice provided this summary of her research experience with bird netting on Long Island:
In the late 80’s, growers here invested in over the row ¾” mesh extruded black plastic net. It worked well for years, whole industry invested in it. One issue with this net was tacking it down adequately to discourage access from under the net. Despite good efforts, birds not only infiltrated under the nets but directly through the nets. The mesh size discourages but does not prevent bird damage. This is adequate for low to medium pressure blocks but may not be sufficient for high pressure blocks. With over the row netting, we also have problems with lateral shoots growing through the top, making removal difficult and sometimes ripping the net. Many growers still use this net but a number of high pressure blocks have switched to other net.
Probably 8 or 10 years ago, a representative from Gintec introduced their side netting to us. It was originally a type of shade cloth. It was pretty revolutionary – side netting with a smaller mesh size. Growers liked it especially since it can be gathered with zip ties and stored in the vineyar attached to one of the catch wires. Growers also use it on outside rows early in the season to discourage deer browsing of young shoots. This practice is not as common in recent years as many blocks are now enclosed in deer fence. We eventually found that in high pressure blocks, the Gintec net does not hold up as it is not lock stitched. The birds learned that they can make holes in the net with their beaks to access fruit. In our research vineyard, the Gintec alone was not working well so we now use Gintec together with a ¾” mesh side net. The two together seem to do a good job.
