Its good to water foilage but at certain times of the day. I know my maple can get that white mildew so i try not to.if u do it alot i would think its not good especially if water sits through the night. My other trees like chinese elm or my conifers i do more often but i make sure the water will evaporate by night .My satsuki azalea also benefits from watering the foilage. Im not a proffessional but ive been studying the last 3 years straight. I would say to leave the leaves on but i dont want to give wrong info. Maybe its even possibly to rub it off. I would spray maybe once a week till it goes away and let the trees drop the leaves cause fall is coming

Hi im from ny right by u! My shin deshojo maple had this last year but this year it didnt. I can say this year i dont ever water the foliage and i havnt gotten it this year. I use bayer 3 in 1. Its tough to say but i spray once spring once in fall. Or i kno some people wont spray at all until they see a problem arise.also i would say most deciduos here are prone to leaf burn also. So its best to get them afternoon shade.i wouldnt spray and leave the tree in the hot sun also.