
Can you put another barrier along it temporarily, so she can't get right to the fence? That might help a little bit. It won't cure the problem, but it might ease it and help with training. Not quite the same but I was struggling with Abe running at my chickens as they all gather at their fence line hoping for food, and I didn't make any headway until I'd put a second fence a few feet in front of it. He could still see them but without being able to get right up to them he stopped charging because it just wasn't as rewarding and now, I've opened a bit up again so he can get right to them, but he still doesn't charge. If he does, I can call him off more easily as he's not so riled up about it.
In the meantime, work as far from that fence line as you can, rewarding any break in reactivity that appears and encouraging her to come away the rest of the time. It will take a while. There's a great video showing it being done with clicker training, I'm just trying to find it or a good alternative to link to for you. I'd also be working on making the garden a place where she does other things - enrichment toys, training, scentwork etc - so she's thinking about that more than the fence.
Alternatively you could try straightforward classical conditioning: when the dogs start yapping, she gets a mountain of amazing food and excitement from you and you come in after about 10 seconds. So yapping=brilliant and in a fairly short time, she should start hearing them and orienting to you rather than kicking off.