I posted this question in another conifer forum, and didn't get much response. I will try it here. I found that after about ten years or so, my Chamaecyparis pisifera 'Boulevard' or 'Snow' etc. seem to progressively lose more and more of the nice coloured leaves. Are they expected to be replaced every 10 years or so? Another related question is, after they lose much of their leaves, is there any hope of recovering, or should they be destroyed and new ones propagated?
I've measured a 'Boulevard' 33 feet high. There is no built in obsolescence, other than the normal opening up of the crown to reveal the old dead foliage. From the wording of your posts here and on GardenWeb it is not clear whether you are talking about this or the unnatural deterioration I am seeing on some examples here, which I attribute to some sort of newly noticeable pathogenic agent. In this instance the plant does gradually die away. I've got one in Island County, WA doing this. It is less than 3 feet high, did not look conspicuously abnormal when planted a few years ago.
Thanks for the reply. I am trying to establish whether the deterioration is naturally or unnatural. I have one about 6 ft tall that was a good looking specimen for about 10 years, but starts to show sign of deterioration toward the bottom in the last couple of years. Another one that is about 4 ft tall lost most of the bottom leaves probably partly due to perrenial crowding, and another 3 ft one only has about 20% leave left. If the cause is pathogenic, I presume there is not much hope in stopping the deterioration.
Sounds like the same blightlike condition I am seeing here. Probably there is a spray program that could be undertaken, once the cause was identified.
Thanks for the advice. I will attempt to rescue the two that still have more than 50% healthy leaves.
I know very little about plant disease. Do you mean Phomopsis blight? I was thinking of applying some Benomyl (which I have but not used for many years).
Junipers get that and some others. If you have a commercial interest particularly maybe you can get some assistance from local agency in identifying problem. No point in making pesticide applications until you know what, exactly, you are dealing with.
