Treetec arborists can provide chemical treatments and advice for dieback in conifers around Melbourne and Victoria. Please read the information below carefully and then email or call for a quote.
In Europe dieback of Conifers is more likely to be from one of a number of Conifer aphids (Cinara spp)
In Australia we are seeing the spread of a fungal disease which is becoming more common on various exotic Cypress trees.
Fungal spores enter a tree through wounds in the bark which could be pruning cuts, cracks, insect holes, storm damage to limbs etc and interfere with the conducting system of the Cypress tree. The spores are usually spread by wind and water splash.
Usual symptoms include dieback from the top of the tree down or selected branches browning and dying throughout the canopy, a branch can change colour over a period of days.
You may (but certainly not always) see thin, elongated cankers on the stems, branches and branch axils. These cankers cause twig and branch dieback. Most cankers are wounds, slightly sunken, with raised margins, and they may be discoloured dark brown to purple. Cracked bark in infected areas is often accompanied by extensive resin exudates that flow down the diseased branches and trunk. The cambial tissue beneath oozing sites is discoloured with a reddish to brown colour.
It is important to catch Cypress Dieback early if treatment is going to be successful, once most of the canopy has browned off, it is too late.
2011-13 has seen a large number of cypress trees with dieback and damage, we are getting enquiries from accross Victoria, Western Australia and NSW. if diseased trees can be nursed through this period of unusual weather conditions it may be possible to retain them long term, however even treated trees do not always survive and recover.
We believe the long period of dry conditions weakened the trees, particularly the root systems, they were then hit with a period of above average rainfall and optimum conditions for fungal attack. The primary issue is tree stress.
Monterey Cypress (Cupressus macrocarpa), Lambert's Cypress (Cupressus lambertiana), Lawson's Cypress (Chamaecyparis lawsoniana), Italian Cypress (Cupressus sempervirens), Arizona Cypress (Cupressus arizonica), False Cypress or Lawson’s Cypress (Cupressus lawsoniana), hybrids: x Cupressocyparis leylandii including cultivars ‘Castlewellan Gold’, ‘ Leighton’s Green’, ‘Naylor’s Blue’, and ‘Swane’s Golden'. There are other susceptible species.
Less susceptible trees
Arizona Cypress (Cupressus glabra), Mexican Cypress (Cupressus lusitanica) Bhutan Cypress (Cupressus torulosa)
How to treat conifer dieback
Trees are much more susceptible to dieback when in poor condition and stressed. Make sure root plates are not compacted, damaged or water logged. Ensure water and nutrients are available and any treatments such as pruning are undertaken by a suitably qualified arborist to ensure cuts are in the best possible position and further damage is not done with the use of climbing spurs.
The first step to treatment of Cypress dieback is to have plant and soil tests undertaken to determine the pathogen - that is, find out exactly which disease is causing the symptoms. Departement of Environment & Primary Industries (DEPI) can help with this process, there is a testing lab at Knoxfield. You can engage an arborist to collect and deliver samples however it is often simpler to do this yourself.
Treetec can provide chemical treatments both foliage applications and injections however it is still important to look after plant health as outlined above. Our treatments are getting good results and most trees if treated early are surviving. It needs to be understood however that the chemical is not directly killing the pathogen, rather it is working with a 'complex mode of action' effectively helping the tree to help itself, which is getting the results, currently our success rate is around 60 - 80%.
There is no recognised 'fix' for this disease, the treatments to date appear to be providing enough assistance to the trees to nurse them through, hopefully until environmental conditions improve.
There is simply no published scientific data on the effect of the chemical our arborists use for the control of Cypress canker once infection has taken place. However there is abundant evidence of the effectiveness of this chemical on Phytophthora and Pythium diseases. The latter are water moulds, not even in the same family as the Cypress canker pathogen, Seiridium, a true fungus. Hence extrapolating is difficult and not advised. However, the mode of action of this chemical is not fungicidal, rather it enhances the plant's own defence mechanisms (e.g. programmed cell death in compartmentalisation, production of anti-fungal compounds, thickening of cell walls etc.) hence keeping the disease pathogen in check. Part of the pathways of these complex processes is the requirement of the presence of the water moulds to send out chemical signals to the plant host. These signals (in the form of stress metabolites) are released by the pathogens in contact with the chemical, hence these are specific interactions between the chemical and the pathogen, as well as the pathogen and the host plant. The chemical is not known to result in similar effect on the true fungi as it does on the water moulds. Hence difficult to suggest that it works on fungal diseases. However, our treatments and anecdotal evidence strongly suggests that this chemical may have some effect on some tree diseases caused by true fungi. The chemical processes may be different, but the outcome may be similar in that the tree's defence mechanisms are activated, hence keeping the pathogen in check. Also, it is important to note that this chemical is not strictly a fungicide in the way that it is applied, ie. the concentration recommended has no fungicidal effect (does not kill the pathogen) although high concentrations will kill fungi and water moulds, but at these concentrations the plant host will die first!
The short of it is that we do not have sound scientific information to support our treatments on Cypress canker, the chemical is not strictly a fungicide in its application and there is no guarantee, however we usually get positive results.
Phone: 03 8644 8005
Hedge Image lifted from Royal Horticultural Society UK Website.