Sullivan Pine looking unhealthy

Question: I have two 8-9 foot Sullivan pine trees in my back yard. They have been planted there for 3-4 years. They get about 5-6 hours of sun. One looks great while the other has a lot of die back on the inner lower leaves. The other has no die back at all. Also the unhealthy one looks much less green than the other, a duller green than the other one. I have noticed that the underside of the branches are brighter green than the tops. It gets about an hour less sun than the healthy one. The one photo show you the healthy tree (far left) compared to the unhealthy tree (far right). Another photo shows die back, and the other show unhealthy tree branches. Any thought are appreciated, Thanks, Kerry

responder: Julie Crick  Replied July 11, 2024, 9:17 AM EDT
response: Hi Kerry, I suspect the difference from one tree to the other could be related to a water or root issue. And this looks like a variety of northern white cedar; I'm not familiar with the name sullivan pine.  The overall difference in color from the tree on the left may be because of too much or too little water that the tree is receiving. It could also be that the tree was planted too deep, or with girdling roots, both of which may cause the tree stress which could lead to the duller green color. You can look under the branches and check to be sure the trunk widens a bit before the soil begins, and be sure that the mulch is pulled back 12-18" from the trunk itself. It's not great for the mulch to be right up against the trunk, it's better if mulch just covers the root base.   I suspect the dying inner branches/leaves may be a fungal issue, likely caused by out extremely wet spring and summer (not include the past couple of days!). Below is a link to an article on arborvitae (which is another name for northern white cedar) needle blight. Please take a look, and compare the pictures to what you have been observing on the cedar.  https://ag.umass.edu/landscape/fact-sheets/arborvitae-needle-blight This is treatable using a fungicide on the elongating new growth in the spring. You can also prune out the affected branches now, to prevent spores from the fungus causing the needle blight from spreading. Then, dispose of them offsite as the branches will continue to produce spores. You may dispose of them in trash destined for the landfill, or burn if its safe to do so.   There is a lot of information in this reply. Please do feel free to reach out if you have any questions.   Thank you, -Julie

responder: The Question Asker Replied July 11, 2024, 11:03 AM EDT
response: Julie, Thanks for the quick reply. I just found the label from the Sullivan and it is a Sullivan False cypress. Does this change any of your thoughts?  If not, do you think I can apply a fungicide now? Also the branches that have the die back are very large bottom branches, cur=tting back will really alter the look of the tree. Do you still think this is a good idea?  Thanks, Kerry  On Jul 11, 2024, at 9:17 AM, Ask Extension <<personal data hidden>> wrote:

responder: Julie Crick  Replied July 15, 2024, 10:11 AM EDT
response: Hi Kerry, Thank you for the species clarification.  This does not change my initial recommendations.  I recommend looking closely at the branches that have turned brown to look for any sign of insect (aphid) feeding, or signs of fungus infecting the branch (sunken areas of bark, discolored bark, exuding sap). If you see signs of canker, then it is best to prune the branch. Aphids can be treated with an insecticidal soap.   If do not see any signs of the above, then it may well be heat, lack of or too much water that is the cause. If is a factor of the environment, then there is no reason to prune the branch.   Because the overall color of the tree is off, I suspect it may be a watering or planting issue.   Feel free to stay in touch on this if that helps.   Thank you! -Julie

responder: The Question Asker Replied July 15, 2024, 12:20 PM EDT
response: Thanks so much. I will reach out again if needed. Kerry  On Jul 15, 2024, at 10:11 AM, Ask Extension <<personal data hidden>> wrote: