Yes, the tree appears stressed; the evidence is the browning foliage. There could be several reasons for this: some of them possibly can be stopped, and others result in death.

The Environmental Causes Of Brown Needles: Pine trees can survive a fair bit of inclement weather, but may brown in response to heavy rain or extreme drought.

One of the common reasons for pine tree browning is its inability to gain enough water to keep its needles alive. When it’s exposed to wet conditions, but drainage is poor, they may experience root rot—a disease that attacks the roots of trees and plants growing in wet soil. That may not be the case with yours, if the soil is gravely. However, it probably would be helpful to get a soil test done, so that fertilization would be targeted for specific nutrients that may be missing.

When affected by root rot, pines generally begin to die from the inside out, hence the branch tips die first, then the lower branches. There seems to be evidence of browning on the branch tips.

Watering may also be an issue. At this stage, you still have a chance of saving the pine tree by giving it a deep watering, so that the moisture penetrates the root zone. However, brown pine needles will never turn green, and watering them is just a way of saving the branches from being cut.

If you prune living brown pine tree branches, thinking that they’re dead, will cause the structure of the tree to become thin.

Diseases:

You didn’t mention how long this stress has been evident. A pine tree developing brown needles in the fall may be caused by pine wilt disease, which usually kills affected trees within a few months.

Trees affected with this disease often turn totally brown, and die rapidly in the fall. There is no treatment for pine wilt disease, so your only option is to remove the infected trees immediately, and destroy them by chipping or burning to prevent the disease from spreading to other plants.

Another condition is dothistroma needle blight, which can be treated with a copper based fungicide to prevent new needles suffering the same fate.

Symptoms are needles turning brown and falling off. A tree which has a severe infection of needle blight will likely die off after a few years with the condition.

Mulching around the base of the tree can help, also avoid spraying the needles with any in ground sprinkler system, and maintain good air circulation. Your tree appears to be a good distance from other shrubs, so circulation should be good.

Is It Normal For Pine Trees To Turn Brown in the Fall?

The browning of pine branches can have several causes, and one of the ways to diagnose the problem, so that you can apply the right treatment is to consider the time of year the browning of needles and needle drop has developed.

If the pine needles are turning a brown color in spring, the causes could be infection, weather conditions or insects. After the cold, dry winter, and before new shoots are established, needles that are facing on the side of the winds tend to turn brown.

You can generously water these trees during late summer to replace these needles. If new needles located on the tips of the lower branches are stunted or turning brown, they may be affected by a fungus known as diplodia or tip blight, which you can treat with a fungicide.

How To Save a Dying Pine Tree

Sadly, there are many reasons why a pine tree may look unhealthy. One of the most common is water-related problems. Most pine trees grown in the United States are native to the southeastern states, where the climate is very humid.

Moisture-loving insects and diseases are a huge problem for them in the winter and early spring, and the best way to avoid them is to make sure your pine tree has plenty of water, especially during the winter period.

Ensure A Good Mulch Under Trees

Always try to keep a decent mulch layer under the trees, a 4 inch deep layer is ideal. Wood chip mulch sourced from healthy trees works well, check the depth every year and add an additional mulch layer if necessary. This will help to protect the roots, and also inhibit weed growth. Your tree has green plants growing under it, which may be taking some of the moisture and nutrients that the tree needs.

To be absolutely sure how to treat your particular pine tree to determine why it is turning brown, and for a more specific analysis, you may wish to consider engaging a
Certified Arborist. We suggest Certified Arborists because they must pass a test and must acquire continuing education. You can locate such individuals at http://www.treesaregood.org/findanarborist/findanarborist.aspx

The following links may also be of help to you.
https://www.canr.msu.edu/news/why_are_my_pine_trees_turning_brown
https://extension.illinois.edu/news-releases/when-worry-about-needle-drop-white-pine-trees