One-sided dieback on Lawson cypress

[Gary Prentice]

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

 

I'm surprised how quick this has been arranged. Maybe they are prioritising recording the spread of P. l.

[Kveldssanger]

Potentially - one of the FC officers remarked at how quick the plant pathologist wanted to visit. We spotted another lawson cypress further around nearer the church that had near identical symptoms, but less extensive (earlier stage of decline). Soil samples, foliage samples, and bark samples were taken.

 

The pathologist did say that P. lateralis may be able to hybridise with Phytophthora of cedars (not sure on the species), which may be an issue - we have mature cedars on site as well. If both harbour Phytophthora, then there may be a risk of hybridisation, therefore.

Edited January 19, 2016 by Kveldssanger

[Gary Prentice]

So the phytophera that kills larch, I forget the species, changed it lifecycle in the UK, and now this suspected hybridisation. I wonder if there are particular enviro entail factors here to increase the odds to promote change. OR I'm ignorant to the fact that this sort of thing occurs all the time and I need to keep up:blushing:

[Kveldssanger]

I can't say I know either, though I suspect hybridisation is a genetic thing that is supplemented by environmental conditions - assuming two potentially compatible species are within close enough proximity to one another, and the conditions are right, then they may potentially hybridise.

 

The larch one is ramorum, no?

[Gary Prentice]

Ramorum, yep.

 

I dislike posting things like that unless I'm 100% sure I'm sure, for fear of being corrected, but can't be bothered to get up and search. I character fault of mine.

 

I believe that P.r changed its lifecycle here to exist on bilberries? As well as its usual hosts.

[Spruce Pirate]

P. ramorum does indeed inhabit Blaeberry, or Bilberry if you prefer. That along with larch and rhododendron are the main species of concern as it sporulates (spelling???) on these species and therefore continues to spread. P. ramorum will infect other species, but not spread. There isn't an exhaustive list of the species it will infect, but it incudes oak, chestnut, spruce, fir, beech too I think. There is a second strain of P. ramorum, which I think is unique to the UK, I think this is a priority for FC Research and Plant Health.

 

The phytopthora I know of in relation to cedars is P. austrocedrae, I know it in relation to junipers, but I think it will affect all members of the cedar family - but not totally sure of this. I think it is a more likely candidate for hybridisation with P. lateralis as they are both soil borne, whereas P. ramorum is air borne.

[scotspine1]

I've dealt with a few P. lateralis sites, felling, burning etc. Some trees seem more susceptible/resistant than others. It wont kill every Lawson on a site where it's present.

[Kveldssanger]

Update: FC couldn't find anything. Nothing at all. Spoke with one of the plant pathologists at the Theydon Bois plant health update 'seminar' and she said she'll come down again to get more samples in April (ideally), so hopefully we'll get to the bottom of it eventually!

 

The area is full of conifers (firs, cedars, cypress, yew, etc) and associated wood decay fungi (Phaeolus schweinitzii). Perhaps this is relevant? That or specific roots on the lawsons are suffering, hence the very distinct dieback with abrupt endings in the crown structure.

[Thesnarlingbadger]

Its really bazaar. Has the other better side changed in turns of dieback since you last visited? I'd say the only time I have seen one side of a tree die off completely and the other side still in good(ish) form is when there has been a demotic change in solid or major root damage on that side, like when you see a tonne of gravel or something left on the roots.

I hope you get to the bottom of this mate.

[Kveldssanger]

I haven't been up to the cemetery in a few months, so will go and have another look. As the grounds need 'permission' from the Church to dig, it is almost certain that nothing has changed in the soil for many years (closed cemetery). It's so odd, and there are a few more lawson exhibiting exactly the same issues (one side dying back). Will make a note to go back there on Tuesday and get some more photos.