Hinoki Cypress

Question: I have a 15 year old perennial flower garden including a Hinoki Cypress. It is in an are with a high water table near the Chesapeake Bay. The garden has prospered with only a few of the plants needing replacement after planting. The Hinoki Cypress started to die last year. It continues, as you can see on the attached pictures. It is putting out new growth on the tips of the branches and top of the tree, but there is only a tiny bit of new growth on the old wood.

We have had several tree services look at it. There have been several treatments (don't know what) and a root collar. 
recently a treatment for phytophthora was suggested with the caveat that it probably wouldn't work. We met a professor of horticulture at a nursery who when he heard that there was new growth on the new branch tips and top of the tree but none elsewhere suggested that it probably is a soil born disease.

The professor told us to contact you. We need to if and how to save the Hinoki Cypress; and if we cannot save it, what type of plant can we plant in the same location? Is there a soil treatment? Is there a type of plant that is resistant to the disease? How should we proceed?

responder: The Question Asker Replied June 02, 2023, 1:45 PM EDT
response: I just sent an earlier email on this topic. Attached are two more pictures of something I found on the bark of the main trunk of the tree. I don't know if it is sap or a bug or borer.
Thank you.

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied June 05, 2023, 4:06 PM EDT
response: Hi,  It is hard to say for sure what caused the decline of the tree, but unfortunately it probably isn't going to make a come back to the point that it looks 'healthy'. The damaged that has happened will not necessarily go away.  Do you know what the watering has been like? We can see some type of irrigation and the hoses so we were wondering if it has been watered regularly? or potentially too much? The salt water or air could have contributed to it. The sap that is seeping out doesn't necessarily mean that it has borers, but it could. Usually borers area a secondary cause to a trees decline anyways. If the tree is stressed or dying tree borers could sense that and find it as a nice food source and habitat. If it is a soil borne fungus, which are naturally occurring, there really isn't a treatment at this point that could be helpful or reduce the damage that has been done.  If you are hoping for an interesting focus point, we would recommend probably replacing it. Not that it is native but a Japanese Black Pine could be an interesting specimen and could handle a little more of the salt tolerance.  If the tree had sentimental value, maybe letting it decline but then used as a trellis for a climbing vine like Clematis would still be an option?  Let us know if you have further questions about this.  Emily

responder: The Question Asker Replied June 05, 2023, 4:50 PM EDT
response: Thank you so much for your thoughtful response. The tree is beautiful and we have become very fond of it’s artistic, irregular shape over the years. I think you may be on target about over-watering watering. WE have a soaker hose system set up to water a long perennial garden, although the rest of the perennial garden on either side of it has not suffered. We are going to try to let it dry out a bit without stressing the other plants.     A question we have. If we have a soil borne fungus, are there any restrictions on what we can plant? Unfortunately, we probably can’t replace it with the Japanese Black Pine because it is too big and dense. We have learned that our neighbors are unhappy with the Hinko Cypress blocking their view down Knapps Narrows to the Choptank River. We need to find something shorter, maybe 4 feet high, or if taller than less dense.     Thank you for the nice creative idea for a trellis. We’ll see how handy I can be.    Best, Leslie

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied June 07, 2023, 9:54 AM EDT
response: Hi Leslie,  Most plant diseases stay will the plant material so if you remove the cypress and let the soil dry out, you should be ok to plant something else. Unfortunately a lot of evergreens don't do well in wet soils, so if you change the irrigation pattern or placement for your future plant, that would be best.  You can read about some root rot diseases, on your webpage.  There are a lot of dwarf cultivars of various evergreens now so finding one in the 4' height range or that is fairly slow growing shouldn't be an issue. Some people like different evergreens that are graft onto a single trunk which gives it a sculptural quality. If you search for 'evergreen lollipop trees' or 'topiary standards' that can give you some ideas. Maybe something like a juniper would perform better with salt spray. Personally, this look can be a little too formal for my gardening taste, however if you underplanted with an interesting ground cover or added some native ornamental grass to soften the pruned topiary look, it could be a nice addition to your garden bed! Browsing around at your local garden center and asking for dwarf evergreens or topiary evergreens, could give you some thoughts on what is available near you.  Good luck! Emily