One-sided dieback on Lawson cypress

[Kveldssanger]

No changes as far as I know. Scraped some bark off - nothing looked off.

[One Buck]

- Maybe a tad obvious, and I know you said that you had examined the stem at the base, but have you considered this?

 

Phytophthora lateralis - Tree pests and diseases

[daltontrees]

It's possible that there is more than one thing going on. The separate stems are likely to have discrete rooting systems. Whatever has affected the left hand stem is likely to be primarily a rooting issue. Aphids may well be present. However, had it just been aphids then why was the whole tree not affected equally.

 

Have a dig around the rooting environment and check out the ground condition as well as the roots you find for any clues.

 

That's my thinking too, root or root collar dysfunction, affecting so far only one side. I'd pretty much rule out aphids, but you could check for black sooty mould adhering to shoots.

 

More likely to be biotic than abiotic, but abiotic factors could be responsible partly, by stressing tree and making it more vulnerable to infection.

 

P. lateralis is a definite possibility. You'd have to expose wood right down at the base to look for lesions. I'm not sure whether you would have to notify it, but if you have grounds to suspect it perhaps the FC would be interested in helping with confirmation.

 

It would certainly rule out replanting with Chamaecyparis and probably Thuja, maybe Taxus. Again the FC might be able to advise, and I think they have already published something 'cos I read it somewhere a while back.

[Kveldssanger]

Thanks, guys. I was thinking it would be a root issue, principally because of the fact it's isolated to one stem of the two. I only threw aphids out there as there was dieback in the lower section of the live crown.

 

I shall email the FC on Monday at work.

 

There are some other conifers very close by - cedars, pines, other lawsons, and an allegedly 1,500 year old yew tree (it's at least half that age, by the mere fact it existed before the church alongside). One of the pines, as well as the other lawson, are showing signs of ill-health.

[Kveldssanger]

FC are coming down next Tuesday to test for P. lateralis.

[daltontrees]

FC are coming down next Tuesday to test for P. lateralis.

 

Keep us posted, will you? I've only seen P.l. suspects from a couple of metres away, not able to trespass to confirm my suspicions. I am pretty sure I saw one in Oxford last summer, the dieback had been so rapid that it was hard to comprehend how anything could take a tree from full vigour to fox-brown and completely dead so very quickly.

 

There were such jitters about this disease a few years ago then it all went quiet. When you think how many Lawsons there are in gardens, it would eb quite devastating if it swept through the country. But it's one of those Oomycota I think, and maybe doesn't spread by aerial spores so much as by ground water, so maybe can be contained.

[Kveldssanger]

I shall indeed keep you informed. Very few confirmed sighting on the FC's map. I doubt it's that rare. Probably a lack of reporting.

[treeseer]

A picture of the root collar might help. Bleeeding lesions?

 

Odd pattern of dieback.

 

Maybe a spill of some sort?

[Gary Prentice]

 

There were such jitters about this disease a few years ago then it all went quiet. When you think how many Lawsons there are in gardens, it would be quite devastating if it swept through the country.

 

I'm undecided if it actually would be that much of an issue. Accepting that a percentage of trees wouldn't be replaced, it's likely that those that were would be replaced by a number of different species - so more diversity. A downside would or could be lots of trees of a similar age.

 

In the grand scheme of things nature evolves, those that aren't susceptible or have some immunity reproduce and some sort of dynamic balance results. I'd rather see ten different cypress species in ten different gardens than the ubiquitous Lawsons in every one.

 

I suspect the end result will be a net loss of canopy cover overall, with people not bothering to replant for a myriad of reasons. Just my two pence worth.

[Kveldssanger]

FC came down today and took a load of samples. Will keep you posted. May be a few weeks.