Tree experts say green ash trees that are losing leaves in Le Mars and other parts of northwest Iowa have a common fungal disease, not an insect problem, and the trees aren't dying. Last week, state ...

ASH: Green ash leaves turn yellow, but white ash has a purplish cast. The leaves fall after those of walnut trees, but earlier than those of oaks and maples. BUR OAK: Buff to yellow colors predominate ...

Have you ever wondered why the leaves change color during fall? Well there's a scientific word for this process called, photoperiodism. It's the organism's response to seasonal changes in day length.