Hello Jim,

Non-native pines such as the Austrian Pine have some problems that could cause needles to turn brown and could lead to the death of the tree. Identifying the area of the browning of the needles, and the environmental factors affecting the tree, helps in identification of the problem.

The photos you show indicate that basically the whole tree has turned brown and from your post it appears to be rather suddenly.. Below is a description of three diseases affecting the non-native Austrian Pine: Pine Wilt Disease, Dothistroma needlecast infection, and Diplodia tip blight.

The first, Pine Wilt Disease, appears to be most accurate in describing the photos that you show, especially if this is a rather sudden dying. Pine Wilt Disease is caused by the pinewood nematode, and for a definitive diagnosis, nematodes would have to be determined by sending in samples to a professional lab, such as MSU Diagnostic Services on Campus. https://www.canr.msu.edu/pestid/

Pine wilt has several characteristics that can be used to identify whether a diseased tree is Pine Wilt nematode infected.. Pines infected will exhibit wilting and browning of needles. Symptoms progress rapidly until tree death, sometimes very quickly for stressed trees, typically Scots and Austrian pines. Trees infected will have dieback of whole branch segments, and the needles will turn brown. Pine Wilt Disease (PWD) is caused by nematodes which enter through injuries caused by the Sawyer beetle, clog up the vascular system, leading to the death of the tree. There is no effective treatment. Diagnostic testing is required to identify PWD, which is usually lethal, and the tree should be removed to prevent infecting other trees. Here is a link to an article that more fully describes this

https://www.canr.msu.edu/news/loss_of_exotic_pines_in_michigan_from_pine_wilt_disease

Two other diseases that also cause browning of needles are as follows, and need to be considered based on what you can observe:

Dothistroma needle blight has browning of older needles as well as bare branches from needle drop. Needles on the lower branches are usually more affected with newer branches twenty feet up, rarely infected.

Diplodia tip blight kills needles at the tips of branches. Symptoms often start on the lower half of the tree and progress upwards. ADiplodia tip blight causes entire needles to turn brown, not just tips of needles as might occur with Dothistroma blight. A telltale way to determine if a tree is infected with Diplodia tip blight is to look for the signs of the pathogen, which consist of tiny black, fungal fruiting bodies that are formed on the surface of infected needles and cones. This disease can also form perennial cankers that can cause sudden branch death.

I have included a link that compares all three diseases.

http://hyg.ipm.illinois.edu/article.php?id=216