bird pest

Author : Wines & Vines

For years netting was not considered a real option for the winegrape grower. "Too expensive", or "Too much work for too little results". Well, times have changed, and more importantly the cost of an acre's worth of Chardonnay has changed too.
Netting is now the most effective tool available for bird damage control. There are several types on the market. The grower need not go much further than a Gemplers catalog, orchard supply house, or let his fingers do the walking to find a source of netting.
Cost? Well, some are too high and some are so low you have to wonder what you're getting. Like with anything else, if it seems to good to be true, it is. Many a grower has bought into some sort of device that promises to make a noise only birds can hear, or a vibration that throws off their balance. Unfortunately, the money spent did not justify the results. Enter netting, a high-profile, high-cost, labor-intensive way to do something that seems very basic; let's take a closer look at cost and see if that's really the way it is.
Before I even start on materials I want to address labor. Labor costs are not fixed when it comes to bird netting. To a point, the more people you have, the better. Four to six people per roll is a maximum. I cannot, and will not, attempt to predict here how much people are paid and the variance from one group of workers to another with regard to netting expertise. I can tell you that with experience comes speed. Once you've installed netting it becomes much easier. Thinking about how to install the netting invariably proves to be more difficult and in some cases more time consuming than actually doing it. The best answer is to buy a small quantity of netting first, get the hang of it (no pun intended), and then go ahead with the larger project.
For the sake of this article I have created a "sample vineyard". This vineyard is 14.5 acres and contains two blocks of grapes, one with ten-foot spacing between rows and the other with twelve-foot spacing. The net in our sample vineyard will be applied directly to the canopy and allowed to touch the ground on both sides. Pricing for netting and application/retrieval equipment over a five year period follows:

14[inch] U.V.-treated netting         $207.59 per acre
17[inch] U.V.-treated netting         $230.89 per acre
17[inch] Disposable (clear) netting   $395.10 per acre

I do not need to take time here to examine the cost differences of varieties of winegrapes and compare that to the amount of money spent on netting and saved in grapes per acre. I can confidently say that the above costs per acre represent a saving of $700 to as high as $1,900 per acre. If your winegrapes are selling for $700 per ton with a yield of three tons per acre, spending $250 to $300 per acre for netting is a great way to go. I very commonly hear horror stories of the grower with 10 acres of grapes that "lost a little over four acres to the birds". That is a sad reality in this business.
Now that we have the prices let's look at some important notes. First of all the U.V.-treated netting numbers reflect a five-year life. The sun and wind don't normally kill this type of netting. The installation and especially the removal process do. That is why my numbers include equipment to help the grower with the netting. I do not have the space in this article to specifically discuss application and removal techniques; however, it needs to be said that taking care of your netting is money in the bank. The best way to take care of netting is to have good equipment to install and remove it.
Next, these numbers reflect the use of 14X5,000-foot and 17X5,000-foot U.V.-treated netting. The disposable netting is 17X20,000-foot and is clear. There are a number of nets on the market. The most important item to look at is quality relevant to price. As a netting supplier I could supply 3/4 inch mesh netting, made of knotted polyester, with a ten-year manufacturers' warranty. It is available in several widths, up to 55 feet, and any length you want. Sounds pretty good doesn't it! It will only cost you 36 cents per square foot, so let's see, that's $15,681.60 per acre. I'm sure my phone will be ringing off the hook. The point here is buy netting that is going to last but isn't going to cost someone their job if they tear it, because they will. The netting I've used costs between $650 and $850 per roll; $1,500 for the disposable. Disposable netting is great if you are willing to spend the additional money to purchase it every year. It doesn't matter what it looks like when you remove it, and it is every bit as effective as the other types of netting.
The last item I want to touch on is support system. The support system is always the most important part of any netting system. For grapes, you don't need one. The canopy works perfectly as a support system. Some trellis designs give the grower the option of netting the fruiting zone only, attaching at the sides and hanging vertically to ground level, or using the trellis wires for support. Obviously, this varies from one vineyard to another. Don't try to get over-sophisticated with netting. If you do it properly you should only need it for four to six weeks and then you'll be taking it down.

 Let me clarify that. Bird damage usually occurs when the sugar count reaches 11 [degrees]. From then until harvest, you need netting. When you remove the netting you need not wait until the morning of, or evening before harvest. Birds can't see the netting very well, it's a physical barrier not a visual one, so they won't react when you take it off. Take if off, carefully, and store it somewhere it won't get damaged. Remember it's money in the bank.

Looking at the numbers we have discussed, which are real, I can confidently say that netting is worth the hassle. In fact I would like to restate something. Putting netting up, and taking it down, is no more a hassle than maintaining equipment or ensuring proper irrigation, or any other number of seasonal necessities that make up a grapegrowers life. The perception that netting is a hassle has been with us a lot longer than the knowledge that it really isn't that difficult after all. I hope this month's column has been educational and maybe even inspired a few.

Next month, Starling and Blackbird Control.