Q.Why Are My Leaves on My Peach Tree Turning Yellow and Falling Off?
My tree was very healthy a few days ago, but the leaves are yellowing and thinning. It hasn’t rained in a week. Could this be the cause? There is a lot of fruit on the tree, and I know it should have been thinned out, but I did not thin it.

Certified GKH Gardening Expert
A week of no water should not have that effect that quickly. But, it would not hurt to provide water.
Has the tree been fertilized recently? If not, I would add some fertilizer to the soil (after it is well watered to avoid burning the roots). The stress of producing fruit with low nutrients may be too much for the tree and its leaves are yellowing because of that.
As a precaution, I would recommend treating the tree for pests and fungus. I like to use neem oil for this because it does both and is organic. Here is more information. https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm