A some of you know, I have an araucaria araucana, a pair of araucaria budwilli, and several agathis robusta that do winters indoors and warm weather outdoors. I have found this site to be quite useful and have enjoyed viewing others views and information. This may be a question for an experienced arborist or the like: There are a handful of unfortunate stories of seemingly healthy, well-established araucaria araucana suddenly turning brown and dying well before their time. I am curious as to whether someone has identified a specific bacterial or fungal disease that we should be aware of? Is it that the tap root found its way into some form of soil contaminant? Other identified causes of sudden browning of foliage and/or death? I did find some information on a fungus called Pestalotiopsis funerea which is associated with browning of new growth. Sometimes it is triggered by drought and/or cold stress. It may be treated with a copper-based antifungal. However, I am not sure this fungus would rapidly kill a previously healthy, well-established tree...maybe so. I was able to find some anectdotal evidence from Australia that oozing sap might be a sign of drought in some species, such as Agathis. Other than that, most Araucariaceae appear to be disease and pest free. Please share any information.
Hi, I work in the National arboretum (Westonbirt) in Britain. I have seen an Araucaria araucana succomb to Honey Fungus (Armelleria) here although it was an older tree. It seemed to turn brown almost overnight but up to that point it had showed no obvious signs of infection or distress. I haven't heard of any other disease which specifically targets Araucariaceae. Luke
I am curious about the immune response and disease pathophysiology of these trees. I am not a botanist, but most trees, even if they do have evidence of fungal disease, will tend to fight it for quite a while. This often gives the concerned caregiver time to identify and treat the infection. The wollemi pine appears to be further threatened by a fungus, again, in seemingly healthy specimens. Certainly, the whole point of this thread is to help identify certain pathogens and treat our prized specimen trees before it is too late, not to mention that many araucariaceae are threatened or endangered in the wild. Therefore, in my opinion, any sudden death is rather concerning. I know many araucariaceae are known for their prodigious amounts of sap and am wondering if a fungus were to enter the "circulation", would it rapidly spread the fungus throughout the tree? If not, then how would a fungus overwhelm a tree that is otherwise known to be resistant to diseases and pests? Most fungi are opportunistic organisms that generally do not bother their host unless the host is immunocompromised and/or under some form of physiologic stress. This again, is concerning given that these trees often succumb to their disease, seemingly without warning. Perhaps the soil requirements should be reexamined? Some of the Agathis species in New Caledonia grow in a very gritty, simple soil, which appears from photos, to be similar in consistency to "bonsai" soil. I know part of the reason "bonsai" soil is the way it is, is to provide adequate drainage, root transpiration, and reduce the chance of fungal growth. Any evidence that the soil consistency or matrix is more important than previously thought? I am currently scanning the literature and will attemp
