Does anyone know what can be done to help a tree suffering from dieback?
I live on a suburban block with two large gumtrees, and one of them, a Syndey Blue Gum, has started to brown off at the leaves on one side of the tree. Had an arborist look at it, and the quote the left in the mail basically said 'The tree has dieback, it's gotta go'. The tree is over 25 years old, and I really don't want it to be cut down, especially as a third tree on our block (a Silky Oak) had already died a few years ago. Getting the council to look at it, but they're really busy at the moment.
I think the dieback might be lerp related, as there does seem to be a lot of them on some of the older leaves. Other than the (seemingly) dying branches, the rest of the tree seems healthy. There are so few large trees in the area, and the local birds really love the two gums. Most of the stuff I could find on the internet seemed pretty awful, with much of the Blue Gum forest dying back around Sydney. Is there anything that could be done to help it? There's got to be a mid point between risking half the tree die and fall on someone and cutting the poor thing down?
Hi, Lachlan. There is a number of reasons for tree die-back but if you have lots of lerps on the leaves then you've probably diagnosed the problem accurately. Lerp infestations are due to a lack of Lerp predators, particularly small birds like Pardalotes & Weebills. And the lack of small birds is usually due to habitat destruction. The fact that there are few large gum trees in your area means there's lack of habitat for Pardalotes & Weebills such as small tree hollows & outer tree foliage.
As you would be well aware habitat restoration takes a long time so for the long term a widespread programme of ecological restoration needs to begin as soon as the plants are available & there has been sufficient rain to sustain them without costly watering.
For the short term, I'd suggest the affected limbs are removed, the twigs & foliage on those limbs carefully removed, tightly bagged & put in the rubbish bin to get rid of as many lerps as possible. You could try erecting nest boxes suitable for Pardalotes but beyond those two approaches I fear you're probably stuck with protecting yourself from public liability & supporting you local arborist. Welcome to the consequences of environmental destruction.
Thanks Woko, I thought that was going to be the answer.
Problem with removing the affected limbs is that one of the major forks is affected, so about 2/5 of the tree would probably go. Do you think it would revegetate from epicormic buds, or would they have been affected by the dieback too? That way only the outer branches could go... Would look ugly, but hopefully the tree wold grow back fast.
If the tree does have to come down, would the best respose be to simply plant another Eucalypt? Or would I be better off building up the amount of shrubs and small trees in the garden to give the birds some habitat faster?
Hi again, Lachlan. I fully expect the tree will at least try to grow from epicormic buds.
While it's sad to see large limbs go, it may not be the end of the tree. Only a few hours ago I passed a roadside Euclayptus stump & it was already showing 30 cm shoots, the tree having been cut down about three weeks ago. Also, I live close to a Yate Eucalyptus cornuta which was cut down to a 2m stump 12 months ago after die-back appeared in two of its four limbs. This tree now has a bunch of 70 cm shoots although one of them is yellowing. The others look very healthy. So I certainly think that cutting off the affected limbs is worth a try.
If you decide to cut off the suffering limbs I'd suggest you water the tree thoroughly around the drip line to enhance the survival of young rootlets. Of course, if you've had good rains recently there may be no need to do this.
On the revegetation side I don't see why, depending on your circumstances, you couldn't plant another Eucalyptus as well as develop a good understorey of shrubs & small trees. The greater the biodiversity & the quicker it's established the more chance you'll have of improving your bird species diversity. Planting indigenous species will, of course, provide more suitable habitat than planting non-indigenous species - and the more likely your vegetation will survive any stresses that are thrown at it because it will be adapted to local conditions.
The closer you are to a patch of natural bushland with a diverse range of bird species then the more likely you are to attract birds from that patch. If you local council & neighbours are willing to pitch in by planting indigenous vegetation to make a wildlife corridor then so much the quicker & so much the better. Dropping in their laps a few photos of birds that might be attracted might be an incentive for them to do this.
Natural bushland is at a premium where I live- it is former Cumberland Plain Woodland. That's half the reason I'd be very sad to see the tree go; the number of mature Eucalypts in the area is slowly decreasing. Thus, with the two largest gum trees in the street in my yard I get lots of nice birdlife coming through.
Unfortunately, the area was developed in the early 1980s, so there isn't much in the way natives in some areas. Lots of conifers, lawns and exotic council street trees. Still, one of the neighbours has planted a new gumtree, dunno what type it is, but hopefully it's a big one! My question about the natives wasn't an either or, it was badly phrased. I was wondering if I'd better off planting one of the fast growing eucalypt varieties to try and replace the big tree, or if it'd be better to simply plant a couple of smaller ones that would reach maturity quicker?
Knowing that it'll probably at least have a chance to grow from epicormic buds is good. That way if the council take offense at the dead branches when they come to check, I might be able to present an argument for the tree being ok with some pruning. It's a shame that the tree is dying back now, after the awful death of that NSW Primary School kid from a falling eucalyptus branch a month ago, I suspect the council is going to err on the side of 'caution' and suggest taking the tree out.
Most, if not all, Eucalypts grow relatively quickly so whichever species you might plant is likely to provide habitat within a year or two. Given humans' propensity for following fads it shouldn't be too long before everyone in your area will be planting Eucalypts now that your neighbor has got in on the act!
Yes, the tragic death of the school child from a falling limb will likely see a cull of Eucalypts although I note there is yet to be an announcement of a car cull following last weekend's calamitous carnage on the roads. I also note the tendency of humans to blame trees when they build schools & houses under large limbs. We seem to be loath to accept the price of what we deem to be the price of "progress". However, if, in the face of council suggestions, you're able to retain as much of the tree as possible, perching & lookout spots will be available to birds in the short term & nest hollows available in the long term. The anti-environment juggernaut is very powerful & individuals can only do so much within the limits of their resources.
There is a degree of chance involved. Sometimes eucalypts will have a few branches die, then recover and live for many years after. The dead branches don't catch the wind anymore so they aren't too much of a risk for falling. I don't think we really understand dieback, if you see black sections of bark near the base, and lots of sap coming out it isn't a good sign. Live branches like the ones that fell on the school are heavier and more likely to fall if they weaken.
Its sad that a good tree can die through lack of small birds. Bell miners also predate lerps, I understand. Lerps may even be their principal diet. Where I once lived east of Melbourne the bell miners were prolific in the gullies. But they disappeared with the encroachment of suburbia. Its all a fine balance that is easily upset.
Problem with th black section bit is it's a Sydney Blue Gum- they have a skirt of dead and fissured bark around the base. The are blackish, sap weeping cracks in the bark, but it could just be the outer bark. The tree is mature, but still growing a bit; a though the weeping cracks were just a sign of that?
The bellbird-lerp-tree relationship is really interesting. The Bellbirds has been implicated in the dieback of lots of Sydney's High Blue Gum Forest through a phenomenon known as Bell Miner Associated Dieback. Apparently, when some habitats are disturbed, the Bellbirds go nuts in farming the lerps, and exclude all other small birds from the trees. The overabundance of lerps then kills the trees. So then the bellbird colony would disperse, starting the cycle all over agin.
The problem with the world is that not enough people are using condoms.
For Australian birds, natives=life, exotics=death, so do them a favour and go plant some natives and save their lives.