In the beginning of June bought a cherry tree seedling and transferred it from its pot to our yard. It was doing ok but, I saw that two days ago all of its leaves were wilted and some had dried and died. I live in Montreal and I've been watering every 3 days, and it has been raining quite a bit. All other trees and plants seem to be doing fine in the same soil! ( I planted an apple tree seedling as well at the same time and it's looking ok!) What could be the problem?
If we look at a plant as an active flow-through of liquid nourishment, with the leaves as leaky balloons that receive liquid and allow water to escape into the air simultaneously then we can see the deflated leaves as losing more water than they receive from below. So we are looking for a reason for the flow to be interrupted.
The first thing to check is that there is no physical damage to the trunk. If bark has been deeply chewed or bruised this will rapidly stop the flow. Look for small holes where an insect might have bored into the tree. If you observe that only part of the tree is affected then examine just above where the difference occurs.
If it is the whole tree then the root might be the cause. If there are insufficient roots absorbing water then it won't be able to support the whole canopy. Remember that roots need air as well as water to function properly, so if the root area is flooded this will provide the water but no air. Push a rod into the ground to the depth of the root ball you planted and check that the water table is lower than the deepest roots.
Good luck and let us know what you find.