The curling of leaves on your weeping cherry is most likely due to heat stress and the need for water. There could be other issues at work as well though and it would be helpful for us to see additional photos of your tree, including the area where the trunk goes into the ground and a photo of the whole tree/area it's in. Also, let us know how old the tree is, how it is cared for and if any chemical applications have recently been made to the area.
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Thank you for the additional photos. We do not see an insect or disease issue and no chemical controls are recommended. Do not spray a pesticide unless a pest or disease is identified and you know what you are spraying for.
It looks like the tree may be planted too deeply and there is excessive mulch around the base of the trunk. This can cause decline. Also, the leaf curling may be due to heat stress and a water issue such as too much or too little. You did not mention how often you are watering.
Planting too deeply - We do not see the root flare at the base of the trunk. The tree looks like a telephone pole going into the ground. The root flare is where the roots begin to branch off of the trunk. When trees are planted too deeply this can create girdling roots, bark deterioration at the soil line, encourage the formation of weak adventitious roots, or the added few inches of soil over the root ball can deprive them of too much oxygen, especially in compacted or wet conditions. If you do not see the root flare, root collar excavation, which is the removal of excess soil and mulch around the root collar (base of the tree), can be helpful. Carefully remove the excess mulch or soil from the circumference of the trunk to the point where the trunk flares out into root growth. Be very careful with shovels because you do not want to cause root disturbance. Make sure mulch is no thicker than several inches and away from the base of the trunk. Here is more on planting too deeply. https://extension.umd.edu/hgic/topics/planted-too-deeply
Watering - Plants less than two years old should be watered deeply once or twice per week especially during the hottest and driest part of the summer. This encourages roots to grow deeper. More frequent, light watering only wets the surface promoting a shallow root system. Check the soil moisture about once a week up until the ground freezes. Soil should be damp like a wrung out sponge. After watering, probe with a screwdriver to make certain the soil is moist down six inches. Let the soil dry slightly before watering again. See watering guidelines https://extension.umd.edu/hgic/topics/watering-trees-and-shrubs Here are our tips for planting new trees and shrubs. Also see our video https://extension.umd.edu/hgic/topics/planting-tree-or-shrub
This work is supported in part by New Technologies for Ag Extension grant no. 2020-41595-30123 from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.