Our sycamores are looking pretty poor too, with curling brown leaves. I blame the hot dry windy weather and lack of rain. There's nothing you can do - a 15 foot high tree will have its roots down at least 15 feet into the ground so a little tickle with watering can or hose would be a waste of time and water and may make things worse.

The tree will recover as it's well established at 15 years old. If we get some rain in July and August (we usually get a wet spell for the school holidays) it may try again with more leaves.

I'm sure it will be OK again next year, provided the weather is somewhere near normal.

there normaly tough as old boots so i shouldnt worry .

Thanks for the comments. I am optimistic that the
sycamore will recover although I must say, I live in
Northern Ireland and we did not have the pleasure of
a HOT SPELL at any time this year LOL. (iF ONLY) LOL