Hi Adrian, it's good to see a fellow Aussie on this forum.

I'm a newbie blueberry grower myself and have much to learn about it.

Are all your blueberry plant's leaves turning red? Or just that 1 bush?

If all the plants' leaves are turning red at the same time, I think it may be caused by the cold weather. All my northern highbush blueberry plants have shed their leaves last week and half of my southern highbush's leaves are turning red and are slowly shedding off also. It's still early Winter at the moment, give it a few weeks and see if the leaves are sheding.

What is your soil ph level? If it isn't between 4.5 to 5.5, the plants will have trouble getting the nutrients it need to maintain healthy leaf colour. I noticed there are red dots on some of your blueberry leaves, is it very humid and wet in your area? Those might be blueberry rust. Check your lower leaf surface for any orange marks, it's an indication of blueberry rust. Pull them off and burn it.

Here's some info with images look very similar to yours. http://msue.anr.msu.edu/news/be_on_the_lookout_for_leaf_rust_in_michigan_blueberry_fields

Thanks. The soils are at 5.5 when I went to look just the day after I made this post some small black insect ran off and hid themselves. So I got some of that ocp eco oil and confidor, they seem to have gone. They are looking much healthier now. Maybe they had been over watered but I had move them from a large pot into a bed so I thought extra water for a few day's would be ok. I have turned the water off pretty much only water once a week for 8mins will see how it goes. Thanks for the reply. I thought there would have been a stack of people advise me but it seems quite quiet on here.

I grow blueberries in zone 7b USA and that pic looks like autumn fall, one of the reasons I love these bushes, spring flowers, summer fruit and fall color.