Off the leash park barking

hello all , just after some advice. Our lovely summer is growing fast, nine months on dec the 1st. she has been a brilliant pup, I feel awful for having a moan, but this is a very annoying habit she has got into, and it really needs to stop.
We were so happy when she learnt to retrieve and chase the ball, off her lead, and this is something she looks forward to every morning, when I walk her in the park. She walks very fast to the park on her leash, and as soon as I let her off, she starts with the excited barking, and it just goes on and on . We have a field where she runs and chases ball, then a track which I try to walk her on, with no ball, but she just constantly barks until I throw it. It's a nightmare when we meet other dog walkers, as her constant barking totally interrupts polite conversation, and most of them say they can here her coming, as soon as she's let off the leash. She seems to hate me communicating with others, but, if I put her back on the leash, she stops immediately , letting me chat away merrily. It's the same when we do our beach walks, owners casually walking enjoying the pace of life, with their dogs running off the leash, but as soon as we let her off, she starts, and people look at her as if she's ferocious, but they couldn't be more wrong. She's great when she meets other dogs, and loves all people, but this barking is getting out of control and is making our daily walks miserable,instead of enjoying our walks together , I start to dread them. I need to put a firm stop to this behaviour, but am not sure how to. I tried, ignoring her, telling her no, ect, but nothing's working , any suggestions will be great fully received x

I would try more walks on the lead if like you say she's ok then. Another thing you could try is to buy a long line. Take her to the field and gradually let her out until you can drop the line.
Pete

lol what a little tinker! Maybe try putting the ball away when she starts to bark and ignoring her, when she stops get the ball out and throw it?