Hi Grape Friends.

Hope you had a wonderful festive season and that 2008 will be a great grape growing year for you.

In this post, I would like to talk about birds damaging (eating) your grapes. If you are like me, a true nature person, fond of all wild animals (birds included), it is hard not to hate these feathered friends when you are a serious grape grower.

All over the world, grape growers have problems with birds ruining grape crops and the extent of damage to crops, caused by birds of varying types is often significant. Birds damage grape crops by either pecking or consuming whole grapes from bunches.

The former feeding method causes secondary spoilage as bacteria, moulds and insects attack the damaged berries, which may ruin an entire bunch , like in the picture below. Further more, in the table grape industry, which is my speciality by the way, grape bunch appearance is an important feature of the produce and even minimal feeding by birds cause cosmetic damage, making the fruit unsuitable for the export market.
Secondary infection because of bird damage

Now the Million Dollar Question is: “How can you prevent birds from damaging your grape cop?”

Studies showed that strategies to try and 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 an option anymore.
There are a few methods, you as a grape grower, can use to try to reduce damage to grape crops.
Grape growers 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. Propane Gas Cannon
The Propane Gas Cannon 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 Cannons are quite costly and should be placed at strategic places throughout the vineyard. Some grape growers where I live tried to use these cannons, but it seems like birds become acclimated in time to new sounds introduced into the vineyard and tend to ignore the cannon shots after a while.

3 Visual Repellents
I’ve seen grape growers use shiny streamers and other shiny and fluttering objects like small mirrors hanging from strings, to repel birds, but as with the propane gas cannon, 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 (notice I said “could”) repel unwanted birds.
4. Chemical Repellents
No proven chemical repellent (to my 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 – and it could be dangerous to humans! I do not recommend this!
In the end, there isn’t much else we can do – sadly. As my dad always say: “Danie, always remember, you planted the rows on the sides of the vineyard for the birds and grape thieves to eat!” :-) LOL , thanks Dad, maybe I should design a vineyard without any side rows!
Hope you enjoyed the post, try some of these methods, even if they work only for a week or two – it could just be enough to save some of your grapes.
Have a great day
Danie