[BumbleJo]

Just noticed the top of my 3yr old Saturn Apple tree looks pretty sick.  Any ideas, I'm not sure if it's fungal or aphid problem, or lack of water as we've had next to nothing for about 3 weeks though it is heavily mulched and I think I've watered it at least once in that time.  The blossom lower down looks healthy, it's just the tops and ends of new growth.  Advice appreciated. Thanks.   

[Dr_Pepper]

If I had any money I'd put it on Woolly aphid too. Have you seen any earwigs around that area? - they can help control that particular aphid I think http://apples.ahdb.org.uk/woolly-aphid.asp

[BumbleJo]

Thanks for the advice, am now looking at how to deal with woolly aphid.  The tree is in the middle of our perennial meadow so there should be lots of insects around, not sure about earwigs but will look at encouraging them more now. Cheers.

[Trikidiki]

It's powdery mildew.

I have had a few tips with it. I just nip them off and burn them, I did it three days ago and haven't seen any recurrence of it since we've had some rain.  It was probably brought on by the recent dry spell. I wouldn't be too worried if it is only affecting a few clusters of leaves, pick the leaf cluster off and burn it, if it is a large proportion of your tree you will probably have to spray, if you can find a fungicide you can use on apples any more.

Powdery mildews attack all sorts of plants but each plant group is only affected by specific types of mildew. They are endemic but only cause a problem if the weather conditions allow, usually dry weather.

[Dr_Pepper]

Good job I haven't got any money!! Just googled it and I'm inclined to agree with Trikidiki. Thought I could see creatures and fluff in the picture but perhaps not 

[BumbleJo]

Thanks folks, I'm thinking it is powdery mildew now, will treat accordingly.