Waxleaf Privet, Ligustrum japonicum 'Texanum'

Question: I live in West Salem Oregon, planted about 40 Waxleaf Privets on 3' spacing about 5 to 6 years ago and they seemed to be doing great. In the last 2 year or so they are dying off one plant at a time and appears to move along the row from at least two areas. There may be more areas as I am seeing other patches of yellow leaves. So far about 5 plants have completely died or are very close, with at least that many more showing signs. I replaced two so far. The larger one that is about 4' tall, may also be affected.
If attach some pictures is it possible to determine what the cause is and if I can do anything to stop it?
Thank you.

responder: Jay W. Pscheidt, PhD, Professor  Replied March 28, 2023, 8:05 PM EDT
response: I suspect you have a root problem of some kind. The images and description support this. The images show chlorotic leaves with slightly green veins and some with marginal burning. The leaves all seem to be on the same branch rather than just older or younger leaves. Although this a nutrient and/or water deficiency it occurs when the roots are not functioning well.  The cause could be any of a number of issues from gophers working their way down the row (it looks like mounds of soil along some of those bushes) to a root rot fungus that also can go from plant to plant, down the row, year after year. When you dig up dead ones you can look for possible causes around the root collar or on the roots themselves.  Although curious I do not think there are any chemical issues give the nice lawn and weedless garden bed and no issues on the other side of the fence as it looks like the neighbors do not do much gardening.

responder: The Question Asker Replied March 29, 2023, 3:05 PM EDT
response: Professor Pscheidt,     Thank you for your prompt and detailed response.    Some details regarding your observations:  There are no gophers in the area. The mound was created when they were planted and more so when a strip of sod was rolled over from the lawn side only.  I only water in the summer with a soaker for one hour every one to three days depending on how dry the soil is. Attempting to always have the soil down a few inches damp.  Once or twice a year I spread an 8 lb. bag of Osmocote over the area. It seems as though I can see some of it on the ground most of the year.  The bed is larger behind and slopes away to the NNE. I normally use some round up on it once or twice a year. However there are some weeds do well but the shade does help keep them in check.    I will dig one or two up in the near future and send pictures of the roots.  Really hoping to find out if I am wasting my time replacing the dead ones.    Thanks so much for your help!  William Dye  As a retired PLS for the State of Oregon I have taken classes from and helped instruct surveying/gps type classes in the Engineering Department from and with Professor Schultz, then in more recent times Michael Olsen. Both of these guy's are awesome. I could dream of being half as talented and knowledgeable as they are.  However Professor Schultz's coffee has to be the worst I have ever tasted. :-)    On 03/28/2023 5:05 PM Ask Extension <<personal data hidden>> wrote:

responder: The Question Asker Replied April 27, 2023, 12:35 PM EDT
response: Here are some pictures of one of my waxleaf privet. The roots are still damp from the hosing the mud off. I’m sure they are dry by now and I could send more pictures if that helps. Thank you for your help with this!William, DyeSent from my iPhone On Mar 29, 2023, at 12:03 PM, WILLIAM DYE <<personal data hidden>> wrote:﻿ Professor Pscheidt,     Thank you for your prompt and detailed response.    Some details regarding your observations:  There are no gophers in the area. The mound was created when they were planted and more so when a strip of sod was rolled over from the lawn side only.  I only water in the summer with a soaker for one hour every one to three days depending on how dry the soil is. Attempting to always have the soil down a few inches damp.  Once or twice a year I spread an 8 lb. bag of Osmocote over the area. It seems as though I can see some of it on the ground most of the year.  The bed is larger behind and slopes away to the NNE. I normally use some round up on it once or twice a year. However there are some weeds do well but the shade does help keep them in check.    I will dig one or two up in the near future and send pictures of the roots.  Really hoping to find out if I am wasting my time replacing the dead ones.    Thanks so much for your help!  William Dye  As a retired PLS for the State of Oregon I have taken classes from and helped instruct surveying/gps type classes in the Engineering Department from and with Professor Schultz, then in more recent times Michael Olsen. Both of these guy's are awesome. I could dream of being half as talented and knowledgeable as they are.  However Professor Schultz's coffee has to be the worst I have ever tasted. :-)    On 03/28/2023 5:05 PM Ask Extension <<personal data hidden>> wrote:

responder: The Question Asker Replied April 27, 2023, 12:43 PM EDT
response: If it will help, I have another plant that is not completely dead yet but will be soon.Sent from my iPhone On Mar 29, 2023, at 12:03 PM, WILLIAM DYE <<personal data hidden>> wrote:﻿ Professor Pscheidt,     Thank you for your prompt and detailed response.    Some details regarding your observations:  There are no gophers in the area. The mound was created when they were planted and more so when a strip of sod was rolled over from the lawn side only.  I only water in the summer with a soaker for one hour every one to three days depending on how dry the soil is. Attempting to always have the soil down a few inches damp.  Once or twice a year I spread an 8 lb. bag of Osmocote over the area. It seems as though I can see some of it on the ground most of the year.  The bed is larger behind and slopes away to the NNE. I normally use some round up on it once or twice a year. However there are some weeds do well but the shade does help keep them in check.    I will dig one or two up in the near future and send pictures of the roots.  Really hoping to find out if I am wasting my time replacing the dead ones.    Thanks so much for your help!  William Dye  As a retired PLS for the State of Oregon I have taken classes from and helped instruct surveying/gps type classes in the Engineering Department from and with Professor Schultz, then in more recent times Michael Olsen. Both of these guy's are awesome. I could dream of being half as talented and knowledgeable as they are.  However Professor Schultz's coffee has to be the worst I have ever tasted. :-)    On 03/28/2023 5:05 PM Ask Extension <<personal data hidden>> wrote:

responder: Jay W. Pscheidt, PhD, Professor  Replied April 27, 2023, 1:56 PM EDT
response: The images of the roots under the poor bush seem to show a lot of roots in a compact area. It is difficult to tell but the roots seem to be mostly in good shape. I suspect it was difficult to dig out of the ground which would generally indicate it is not a root rot. Some roots look dark and may be rotted. I always check the cambium to see if that region is white, wet and fresh looking. If not then there could be issues with several different fugal root rotters.   I do wonder about girdling roots. When planting we like to have the circling roots in a pot spread out. As they get older, circling roots will grow larger, impact each other including the trunk and can cut off the vascular system between the roots and branches.

responder: The Question Asker Replied April 27, 2023, 2:42 PM EDT
response: When I looked today after it was dry, I could see his white spots around the root collar that’s in the indication. If it’s not root rot, then I’m wondering if I should continue replacing the dead ones?Sent from my iPhone On Apr 27, 2023, at 10:56 AM, Ask Extension <<personal data hidden>> wrote:﻿

responder: The Question Asker Replied April 27, 2023, 2:42 PM EDT
response: Sent from my iPhone On Apr 27, 2023, at 10:56 AM, Ask Extension <<personal data hidden>> wrote:﻿

responder: Jay W. Pscheidt, PhD, Professor  Replied April 27, 2023, 3:33 PM EDT
response: These new images do show girdling roots. The white may or may not be an indication of the original problem. White on the outside is not as much a concern as white on the inside of the bark. White on the inside indicated Armiallia root rot.  https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-armillaria-crown-root-rot White outside could just be secondary fungi colonizing already dead tissue.

responder: The Question Asker Replied April 27, 2023, 5:29 PM EDT
response: Jay,     I will check the cambium on the roots and do the same on another that is not quite dead.     Thanks again for your help,  William  On 04/27/2023 12:33 PM PDT Ask Extension <<personal data hidden>> wrote:

responder: The Question Asker Replied April 28, 2023, 1:04 PM EDT
response: The photo where the cross-section is all brown is from a completely dead one in the ground. The cross-section showing the green and white cambium is one that had a lot of dead and dying limbs that I trimmed way back this winter. It does appear to have a little bit of new growth. I know it would be hard for you to say for sure but if you don’t see anything that would stop me, I believe I will plan to replace the other three dead plants?I am totally fine with your best guess. :-)Sent from my iPhone On Apr 27, 2023, at 2:24 PM, WILLIAM DYE <<personal data hidden>> wrote:﻿ Jay,     I will check the cambium on the roots and do the same on another that is not quite dead.     Thanks again for your help,  William  On 04/27/2023 12:33 PM PDT Ask Extension <<personal data hidden>> wrote:

responder: Jay W. Pscheidt, PhD, Professor  Replied April 28, 2023, 4:51 PM EDT
response: Go ahead and plant new ones. Prep the hole well and spread out the roots that come with the new plants. A little TLC this summer and they should do fine.

responder: The Question Asker Replied August 27, 2024, 6:24 PM EDT
response: Jay,     Was hoping you are still available for more questions.  I replanted last May and things improved until this year.  One of the 2 replacements planted last year is nearly all gone next to an original that has very little green left. The other 2 replacements are not looking great. An original 20' east of these 3 replacements was the first one replace about 4 years ago and the one to the right had most of it's dead stump removed 2 years ago. The area having a total of 4 plants at 3' on centers, is the only area that currently looks bad.  I was considering letting them go until there is no green left or if that would be a waste of time?  Could the soil be toxic in those area's? After removing 7 40' Douglas Fir trees where the hedge is now, I buried gravel along a lot of the area from an old driveway. The stumps were all removed but a few pieces of the old roots still remain. Thought the gravel would help with drainage due to the clay. This area also has radon gas.  Attached a few pictures.     Thanks for your help,  William              On 04/28/2023 1:51 PM PDT Ask Extension wrote:

responder: Jay W. Pscheidt, PhD, Professor  Replied August 28, 2024, 8:53 AM EDT
response: You might be right about the old stump areas interfering with the growth of the new plants. What to do depends on your goals. Leave them alone and see what they do is the easiest thing. Replace when dead but maybe think about a different set of plants. Or, if you have to have plants making a hedge there new, pull out the ones doing poorly and try something new. I have found that gardeners tend to like planting new plants. Good luck.