Balgash,

… Keep watching for a better ‘answer’ than what comes to my mind… Espaliered trees are tricky to keep healthy. As most ‘free growing’ trees have multiple leaders (or water shoots) constantly drawing nutrients, espaliered trees are often pinched and aimed too early for proper or healthy development. ‘What’s left’ appears more vulnerable to attack and less capable of recovering than a ‘free-growing tree.’

That said, I having no espaliered trees (only deer) and those are strictly my observations. As far as the “curling leaves” – without a photo or on-the-spot analysis … we can only speculate: Lack of water hardly seems likely; or sun-scald (noting the date of your post). Is there any sign of chewing or ‘shortened’ leaves; are they ‘rolled,’ with anything inside? Is there any webbing? Also, check the trunk and main limbs for ‘pin-holes’ and ‘sawdust’ around the base… Could be borers!

You’ve difficult questions, but good ones!

Bagging? I’ve only bagged groceries … many years ago… I think you’ve got the concept. The bagging will / should keep ‘pests’ from them; I’m not sure about ‘apple scab’ - that may have spread by now. I’ve heard the apples won’t ‘color up’ inside a bag and that you’ll need to remove the bag prior to harvest (I’m not sure of the timing) to allow pigment to develop. And, I’m not sure what type of ‘bag’ works best – or where to get them..? (See – I don’t know it all )

But you’ll first need to figure out what’s withering those leaves… As my last, and perhaps most serious fear is borers; look for that ‘sawdust’ then quickly search ‘shothole borers.’ http://www.agf.gov.bc.ca/cropprot/tfipm/shothole.htm -- Don’t wait for or count on us!

Good luck, and please keep us posted, we’re learning too