Sick Pine Tree

Asked June 5, 2019, 10:41 AM EDT

Good Morning, I have several of this type of pine tree in my yard. This one has started to turn brown just in the last two weeks. All the others are beautiful and green. I can see no evidence of any sort of infestation. I fear the tree is dying quickly. Any recommendations? thank you, Mark Seglem.

El Paso County Colorado

18 Responses

Thank you for your question. I believe this is a Ponderosa Pine. I am unable to provide a diagnosis for your issue. Needles turn brown for a variety of reasons to include various diseases, insects and environmental damage. Below is a link that provides good details on plant problems. I would look closely at the brown needles and see if there is any evidence of a fungal disease. Also, winter injury might be the culprit.

Hello Mark,

Thank you for your question about your sick pine tree and the excellent pictures. I have some additional comments to share. Your tree looks like it has been pruned, about 50% of the canopy has been removed which can weaken the tree. Pines are intolerant of being pruned. Trees under severe stress should not have any live wood removed. Medium aged trees, depending on actual growth and vigor of the tree, should have no more than 10% to 25% of the canopy removed. I have included some links about Pruning Mature Shade Trees and Pruning Evergreens below.

Most of the pruning cuts that I could see looked good, the area around the branch collars are beginning to close. There is one cut that that has removed part of branch collar, the wound is oozing, and the area above this cut looks off color. It is possible that decay has entered into the tree at this site. Please see the fact sheet below which discusses Tree Growth and Decay.

It is possible your tree was planted too deeply and has some girdling roots, the trunk goes into the soil like a telephone pole, there should be some root flare at the base of the tree. I can see a small root at the surface of the soil. Causes could be root deflection at the edge of the planting hole, the roots were circling in the container, planted too deeply, mulch over the root ball or root flare, etc.. Girdling roots can choke the tree to death which can happen 10 to 20 years after planting or sooner. If you dig carefully down a bit you may be able to see a girdling root. Be very careful about trying to cut a girdling root, which could be under a great amount of pressure, an instructor had a root snap and whip which could have caused injury. Please see the section which discusses ‘Dealing with Girdling Roots’. Girdling roots can cause poor health and dieback without any obvious cause and eventually the death of the tree.

Thank you very much for your help. I could not find a girdling root issue, and the needles look ok, just brown. Would it help if I sent a photo of the needles or any other part of the tree? Thanks.

Hello Mark,

Thank you for your reply and offer to provide some more pictures. Close up pictures of the base of the tree, needles on the end of a branch, the off color area above the oozing pruning cut, bark and needles would be helpful. A distance picture of the area around your sick pine that includes a healthy pine would be useful. It good to know that girdling roots are not causing the problem.

Do you by any chance know the species of your pine? From the look of your tree, I believe your tree is a non-native tree, Austrian Pine. Austrian pines are more dense looking than a Ponderosa pine, needles are not as long ( 3-5 inches), have 2 needles per bundle that are a stiff darker green, with a more grey colored bark. Ponderosa Pines have 2-3 needles (10-18 cm long) in a bundle (3 near the top), needles are thick and flexible, and a bark that is more of a cinnamon color that could have a vanilla or butterscotch scent. The bark is furrowed (with vertical grooves separated by narrow or broad ridges), plated (with relatively large and flat portions of bark). (From the Colorado Plant Database Jefferson County Extension) Could you please check the needle bundles on your pine to see if there are 2 or 3 needles per bundle plus how long are the needles? If you have an Austrian Pine, it would be significant. I have included a link below from the Colorado Plant Database, Colorado State University Extension Jefferson County, which prrovides details about Ponderosa Pines.

Have you applied any chemicals near your pine or has there been construction that could damage the roots? Depending on the species and soil conditions, roots can travel 2-5 times the height of the tree. Can you think of any way the area near your pine has been altered, flooding ,etc.? I see a spreader near the tree, has weed killer been applied and what kind? The grass near your pine looks healthy. Have you seen any evidence of exit holes, sawdust or pitch tubes associated with bark beetles or wood borers in the branches or the trunk?

There is a disease that kills Austrian Pines if you have this tree. Pine Wilt/Pinewood Nematode (PWN) Disease, Bursaphelenchus xylophilus, caused by a nematode vectored by Pine Sawyers, is described as, ‘Whole tree fades to a straw color very rapidly (non-native pines)’ This disease is a fatal disease of Scots and Austrian pines, Ponderosas are not susceptible to the disease. It has been found in Denver, Fort Collins and Nebraska and I have heard there was a case confirmed in our area last year. Infection and colonization of pines by the nematodes starts in June or July, but observable symptoms do not normally appear until late summer or fall. The needles initially turn grayish green, to tan and eventually brown and remain attached to the tree over the winter. I have included a fact sheet below and have attached a couple of pages from our book, ‘Insects and Diseases of Woody Plants in Colorado, Colorado State University Extension’. Can you take a look at this information to see if the symptoms match what is going on in your tree and let me know? The only way to diagnose PWN would be to submit a wood sample to our diagnostic lab for extraction and confirmation of PWN.

CSU Extension is launching a new study to monitor disease vectors of the pine wilt nematode disease throughout the Front Range. Please see the quote below.

‘We are launching a new study (funded by McIntyre-Stennis appropriations) to monitor disease vectors of the pine wilt nematode disease throughout the Front Range, focusing on sampling ponderosa pine and sawyer beetles (Monochamus species). This project will help us to develop models of disease exposure and provide us with information to inform land managers and landowners about treatment timing and disease frequency on the landscape.’

I look forward to receiving more pictures.

Thank you.

Barbara, thank you. Please find attached more photos both of my sick tree and of the healthy ones very nearby. I looked at the needle bundles and to an amatuer like me it looks as if most are two needle but some look to be three needle bundles. I live in Woodmoor and there has been no construction close by. The spreader had Scotts weed & Feed in it and i have used Triazicide in the past to control grubs which helps control the voles. I have seen no vole mounds anywhere near the trees. I have seen no evidence of bugs or beetles or any infestation in the trees. The needles look clear of fungus or anything else. My next door neighbor did treat one of his pines last year for a boring beetle last year but i have seen nothing. If needed I am happy to participate in any studies going on. Thanks again for all the help. You folks are the best. Mark.

Hi Mark,
Thank you very much for all the information and pictures that you have sent. I am going to ask our Extension Agent,who is a member of our Ask an Expert Group, to take a look at our email chain, I will share with you her response. I looked at the needle bundles and could only see 2 per bundle. The tree's death could be caused by a combination of the Turf Weed and Feed, which can kill broadleaf plants (weeds), combined with the pruning and pruning cuts.
Please consider your tree to be a broadleaf plant sitting in turf.
Thank you for your offer to participate in the study if she thinks your tree could have PWD.

I have also included a link about Broadleaf Weed Control in Lawns.

It is positive that your other trees remain green and healthy.

Thank you for using the Ask an Expert site.

Thank you, Barbara. I look forward to hearing from her.

Our agent should take a look at the email chain tomorrow or Tuesday, I have already sent an email asking her to take a look at it.

Thank you.

Hi Mark,
I have not heard from our agent so I will reassign your question about your sick pine tree to the Plant Testing Lab which has been active on the Ask an Expert site.
Thank you for your patience.

Thank you!

While the tree does not appear to be fully grown, it seems that it has been in this location for a number of years. There could be several things that could be happening. It appears that the tree is isolated in an open area, making it susceptible to drying winds that can cause it to become desiccated. You may need to be sure it is getting enough water. The tree seems to have also been pruned back quite a bit which can stress it considerably. This along with dehydration could also be contributing to it dying back. Although disease could be a problem, it appears that the entire canopy is uniformly affected. Usually diseased trees have localized symptoms that affect portions of the tree where parts of it turn brown and other parts may be in various stages of decline. There could, however, be a nematode problem that is affecting the entire root system and the tops of the trees. You can try a systemic pesticide called Bayer Tree and Shrub Protect and Feed. Getting involved with the PWN program may help gain further information about the possibility of nematode activity at your location. The application of the weed and feed fertilizer could have contributed to the problems with the tree. however weed and feed fertilizers contain a 2,4-D type herbicide that kills broadleaf weeds by contact with leaf surfaces. I have personally used Weed-Be-Gone (containing 2,4-D) under pine trees in my yard and have not had any problems with it. Conditions could have been just right, however, for the herbicide in the fertilizer to be a problem with your tree.

Thanks, James. What is the PWN program?

That is the Pine wilt/pine wood nematode study to monitor this disease along the front range of Colorado. Check with Barbara S. (don't know her last name) who is with the El Paso County Extension Master Gardener's Program. The extension office number is 719-520-7684.

Thanks, will do.

Hi Mark,
I am glad to hear you have received a reply from James Self. Our agent missed my inquiry the first time but has sent contact information about the Pine Wilt/Pinewood Nematode study. I have included it below.

"Sorry I missed this the first time. They’ll need to get in touch with the plant diagnostics clinic up on campus. Their website is:

They can also call or email:

Please send all questions to:
phone: 970-491-6950"

The Ask an Expert site is the best method to reach me, you can address your inquiry to me if you cannot reply directly.

I would be interested in the results if you get your tree tested.

Thank you for using our Ask an Expert site.