This is information from our Iowa State Extension and Outreach Horticulture Specialist

The tree in the photos is a Pin Oak (Quercus palustris). Pin oak is in the red oak group. Pin oak was a popular tree to plant in Iowa several decades ago, but is not typically recommended for Iowa gardeners today as they often develop iron chlorosis, which causes the leaves to turn a yellow-green color that does not look healthy. Not all pin oaks develop this condition, as evidenced by the trees in your neighbors yard, but it is very common and difficult to treat. More information about iron chlorosis in pin oak can be found here: https://hortnews.extension.iastate.edu/faq/why-are-leaves-my-pin-oak-yellow-green.

While this particular species is not typically recommended, there are many other species of shade tree that can be good options for replacing an ash tree. That list can be found here: https://store.extension.iastate.edu/Product/14438 Click on the “download” button in the middle of the page to download and open the free pdf file. If an oak similar to pin oak is desired, consider red oak, chinkapin oak, or shingle oak.

Here is the response from our Iowa State University Extension and Outreach horticulturist for your second question.

My top choice for replacing an ash tree is not typically an oak of any species. Two reasons for this are the concerns you presented related to the disease, oak wilt and the fact that most neighborhoods often already have a fair percentage of the tree canopy already in an oak species. Diversity of tree species in residential neighborhoods is highly desirable to prevent future catastrophic tree canopy losses if disease or insect issues emerge as they did for ash species and the Emerald Ash Borer and for American elm species with Dutch Elm Disease. (as a note: this is also why maples are not typically high on my list of trees to replace ash – most neighborhoods have a lot of maple trees.)

If you wish to plant an oak, as mentioned, all are susceptible to oak wilt, but those in the white oak group are less so. I would consider planting, in this order, swamp white oak (Quercus bicolor), white oak (Quercus alba), English oak (Quercus robur), or some of the hybrids between these species such as Quercus xbinumdorum ‘Crimschmidt’ – Crimson Spire™ oak.

Other tree species to consider apart from oak include, Kentucky coffeetree (Gymnocladus dioicus), gingko (Ginkgo biloba), hackberry (Celtis occidentalis), linden (Tilia sp.), and hybrid elm cultivars (Ulmus sp.), especially cultivars like Patriot, Pioneer, Frontier, Accolade, and Triumph.

Happy gardening!

--Aaron