|Powdery Mildew on the lower surface of a Cabernet Sauvignon leaf.|
Friday, January 13, 2012
Thursday, January 12, 2012
We are having issues with Wattle birds this season. I have never seen them this bad.
How do we stop them?
Birds damage grape crops by either pecking or consuming whole grapes from bunches. Wattle birds are a particularly bad pest because they cause peck damage.
|Bird peck damage.|
This pecking feeding method causes secondary spoilage as bacteria, moulds and insects attack the damaged berries, which may ruin an entire bunch, like in the picture.
“How do we stop them?”
Wattle birds are a native species.
Studies showed that strategies to try and physically eliminate birds species, that damage grape crops have a poor record of success and the fact that environmental consciousness is on everybody’s mind these days (as it should be), makes killing these birds not a good option.
|A Yellow Wattle Bird.|
There are a few methods, you as a grape grower, can use to try to reduce damage to grape crops.
1. Bird Netting
You can use bird netting to drape the grape vines with a special net developed to keep out birds. Although bird netting give some sort of protection, it is not fool proof. Draping the netting over grape vines is a time consuming job and no mechanical manipulations (like mechanical harvesting) can be done before the netting is removed again.
2. Gas Gun
The gas gun is a bird scarer, controlled by an electronic timer and 12V battery and create periodic load explosions in an effort to scare birds from the vineyards. These guns are quite costly and should be placed at strategic places throughout the vineyard, but it seems like birds become acclimated in time to new sounds introduced into the vineyard and tend to ignore the gun shots after a while.
They are best moved frequently.
The local council, the City of Onkaparinga, has strict noise pollution laws which limits the amount of 'bangs' per hour.
3. Visual Repellents
We see grape growers use shiny streamers and other shiny and fluttering objects like small mirrors hanging from strings, to repel birds, but as with the gas guns, birds acclimate to these objects quickly. Some grape growers stretch plastic strings over the vineyard and these strings will vibrate in the wind and make a low irritation sound that could repel unwanted birds.
4. Chemical Repellents
No proven chemical repellent (to our knowledge) has been successfully used in vineyards. Normally, the grapes are almost ready for harvest and applying chemicals to the grapes, could lead to artificial flavour to grapes and in the end to the wine.
Wattle birds are a tricky problem and best combated with a combination of the above.