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 attempt to post my findings in the future. That said, fungal infections seem to be most of the culprits of disease and death. However, there appears to be little literature on how the diseases presented in these trees prior to death. Most of what I have read is identification of the pathogen after death. Keep posting information.
Hi, Yes it was. It made it onto the local news...is that how you knew about it? A friend and colleague of mine was the chap who had to take the top of the tree out. I watched from a safe distance. Interestingly, the crown virtually disintegrated when it hit the deck. What I thought was more interesting was the amount of rocking movement in the main stem. I would estimate the trunk (at the top) was moving about 5ft from side to side. The friend looked decidedly nervous !! Luke
No, I had seen the stump when I visited Westonbirt in 2003. I think there was some signage near it, if I recall correctly. That was one massive tree.
It was a pretty huge tree, yes. I can't remember the exact height. The stump is no longer there. It was ground out, probably not long after you visited. A seedling from the big tree has been planted as a replacement only a few yards away. It seems to be doing pretty well and is up to about 15ft in height now.
After quite a bit of time researching the available data, it has become quite clear that (1) Araucariaceae do not appear to be any more susceptable to any particular pathogen. That said, there are many pathogens, nearly all of them fungal. (2) Often times, rare and unusual plant collectors, like myself, could be part of the problem of spreading soil-borne fungi when we purchase plants and seeds. If the plants are planted in the ground (versus in containers), non-native organisms can easily spread to native plants. (3) Fungal infestations in forests and nurseries are devistating both economically and environmentally, although little media attention is given to it. The general public may be unaware of these serious problems faced around the world. (4) Once pathogenic fungi get into the soil, it is very difficult to contain and control. (5) Once a tree is found to be infected, there may be little hope of saving the tree. An old saying: "An ounce of prevention is worth a pound of cure."...or..."A gram of prevention is worth a kilo of cure"...as the case may be. Most of us on this site have a fair knowledge of good horticultural practice, however, I would encourage everyone to do just a little more research on this subject of soil-borne fungi and practices that are known to prevent, control, and treat fungal diseases. Soil composition, watering/irrigation practices, the type of mulch, pretreatment of seeds and soil, and so on, make a difference. There is much on the subject to be learned. Yesturday, I had the opportunity to fly at about 5000ft in a helicopter across Michigan. It was very interesting to note just how many trees may be effected and how diseases in forests can spread quickly and over large areas of land. The effect is quite dramatic as viewed from the sky. Chances are, you may be living in an area effected by pathogenic soil-borne fungi and not even know it...until it's too late to save your prized specimen plant(s).
Of the 3 Monkey trees I've seen die suddenly here, all shared one thing in common that I noticed. They were all planted in low areas of the landscape with poor drainage. They were all under 20yrs old though. Sorry to say no tests were done for fungal pathogens. It is possible that climate change is having an impact on your forests, causing wide spread disease, drought, and pests. British Columbia's Chief Forester Jim Snetsinger reports "climate major factor in BC's forest future" http://www.for.gov.bc.ca/mof/Climate_Change/ It may not be of any interest to you but I thought I'd throw the link in any how. Copper is a wonderful preventitive fungicide, I have great results on my trees and shrubs. Jim.
