How about running an electric wire along the top of the chickenwire fence? I don't know if it works for ground squirrels, but it certainly deters the local plague of cats from entering my garden!
Lisa

It's a lot of work, but you can build chickenwire enclosures around the plants they like. They're just sort of like shallow boxes without a bottom. Also, try to find a wildlife biologist or something at your nearest university and ask them what kinds of smells might repel ground squirrels. Deodorant soap works pretty well at keeping deer away, and mice won't go into a closet or drawer lined with fabric softener dryer sheets. There's gotta be some odor that'll discourage your ground squirrels. Personally, after seeing the way dryer sheets work on mice, that's what I'd try first on any rodent.

We tried a few things this past summer which erradicated the squirrels from our community garden.

1. We dug a 2' deep trench next to the chain link fence. Using corrugated fiberglass roofing material, which comes in 4' x 8' sheets, we buried the sheets so 2' x 8' was left exposed. The squirrels were unable to get a toehold in the fiberglas.

2. We threw gas bombs into the squirrel holes. I don't recall the name of the product, but it is available at Lowe's and Home Depot.

3. We sprinkled D-Con pellets around the perimeter of the chain link fence. Although D-Con is marketed as a poison for mice and rats, it also attracts and kills squirrels.

Please note, we did not have corpses littering the surrounding area. The squirrels went somewhere else to die.

There is a pelleted product available for killing squirrels (can't recall the name, but it comes in a green barrel). It is expensive to use and does not produce the advertised results. D-Con, while not stating that it works for squirrels, does work and works well.

Until I started gardening, I enjoyed watching the antics of squirrels. But when they start consuming my plants and vegetables, the gloves come out.