What is a vineyard pest and how do I know if I have one?

In the last column I had mentioned that this month we would discuss the “legalese” of vineyard pests.  I came to the conclusion that this would be a pretty boring column for everyone but me, so I took a little liberty and wrote the following, which may still be pretty boring, but you can’t win them all!

The term “vineyard pest” covers such a broad amount of animals, birds, insects and weeds that I thought it would be helpful to spend some time discussing them.

Let me establish that I am not a weed and insect expert.  I do know that if you have lots of weeds and insects in your vineyard then you will have lots of birds and rodents as well. Knowing this, I would like to identify what birds and rodents you should view as detrimental to the vineyard.

Beginning with birds; starlings, robins, blackbirds, finches (linnets), sparrows (also called linnets), cedar waxwings, bluebirds, jays, let’s see is that enough.  It is safe to say that most birds in the vineyard can cause damage.  But, not all birds do.  Hawks, owls, kestrels, and other raptors are good for the place because they keep the rodent population in check. 

I have heard claims of damage from quail, but not doves, scrub jays, but not kingbirds.  How is a grower to know without being an ornithologist?  The best thing to do is to know what to look for.  Do you have grape damage or loss?  If whole clusters of grapes are just gone, you’re dealing with starlings, robins, or cedar waxwings.  The only possible exception to this is therarerougecoyote or deer in the vineyard.  This is not normal, but has happened.

If damage is to berries only, not stripped, but still damaged, you would be dealing with “linnets”, bluebirds, and some of the smaller species of birds.  A good rule of thumb is to think about whether or not the bird can fit an entire grape in their beaks.  If they can, they will.  If not you’ll have pecking damage and the subsequent insect damage.  All damage is bad damage, but as we’ve discussed before, some birds are easier to get rid of than others.  Knowing how to identify the culprit will allow you to pursue, quickly, the most effective control technique.

What about rodent damage?  What we’re primarily talking about is gophers, ground squirrels and rabbits.  Gophers would top the list in my book.  Gophers girdle vines at the base, but then so do rabbits.  Gophers are probably the most destructive below ground pest of the group because they move so much dirt.  They cause damage directly to the vine and indirectly by effecting where water goes with the maze of tunnels they leave behind.  The telltale sign gophers leave are the dirt mounds they create during excavation of your vineyard floor.

Ground squirrels cause damage in a couple of other ways.  In addition to tunnel systems, they will eat grapes.  They will chew on drip irrigation lines and emitters.  Rabbits will also chew up your irrigation system.  Rabbits and ground squirrels are also classic disease vectors.  As a rule, if you have family pets and/or children, although not in that order,  you want to minimize the amount of rabbits and ground squirrels available for the inevitable contact.

You know you have damage from these critters when you begin having vine problems that can’t be associated with disease.  The irrigation damage has an irritating, immediate way of “coming to the surface”.  Occasionally, again, you will see similar damage from coyotes or from wild pigs.  Pig damage is pretty obvious, like entire vines torn out of the ground.  And by the way, pigs don’t care about netting, pyrotechnics, or anything else really.  That is a subject all it’s own that I’ll discuss some other time.  Along those lines, you wouldn’t want to encourage raccoons to hang around either.  They are quick, crafty, and you don’t normally have just one.  Raccoons will eat grapes, and they’ve been known to do some pretty creative things with irrigation systems as well.

Deer are also a subject unto themselves.  Normally, grape damage isn’t as much a problem as emerging bud damage is.  You don’t have to worry too much about deer in August-October, but you definitely don’t want them around in March-April either.

To conclude, it is in your best interest to take notice of some of these things when you walk through the vineyard.  It’s strange to think that tripping over a gopher mound or seeing a covey of quail could mean that your grapes are in danger.  But, that’s what vineyard management is all about.  If it was easy, everyone would be doing it.

If you have questions from time to time don’t hesitate to drop me an e-mail at wctmike@aol.com.  I’ll try to respond quickly and hopefully be of some help.