When do the first yellow leaves appear on the trees?

The first yellow leaves appear on trees in the fall. Why does the color change? It’s that simple! The leaves are green in color due to chlorophyll. In autumn, chlorophyll is gradually destroyed due to the small amount of water, so they turn yellow. The color can be different. Why does it all depend? It depends on the pigments in the sheet. If the leaf contains a lot of xanthophyll pigment, the leaf will turn yellow.
Leaves can turn yellow not only in autumn. From a lack of water and nutrients, as well as diseases, leaves may turn yellow.