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Wandoo Trunk Pits

6/11/2018

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​Greetings Fellow Foxies,
A year ago I spotted a wandoo in Candy Reserve that had large strange pits in its trunk and didn’t think too much about it until I found another example in another reserve. In this case a large branch had fallen an affected tree many years ago, leaving beautifully patterned wood after the bark had fallen off.
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​Pits on the living tree are like inverted oval cones, and the damage extends up the tree to the youngest branches.
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​On close examination I could see the tree’s annual growth rings on the sides and a small hole in the heartwood at the base. The sapwood was clean and clear of fungi indicating that an insect was the primary cause.
When I cut a section through a pit I found a small (about 3mm diameter) burrow leading from the base into a more extensive gallery system in the middle of the stem.
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Typical pit on trunk
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Hole at base of pit
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Cut atpit edge shows healthy sapwood
Enquiries have failed to produce an identification
There are similarities to wandoo crown decline as fungal canker was present in the heartwood but there are clear differences.
  • This is very rare and hasn’t spread to any adjoining trees.
  • The sapwood is healthy.
  • I could see a ring of chew marks on the outermost sapwood layer surrounding pit which suggests that some insect comes out of the basal burrow to feed regularly.
  • There must be successive generations of the insect, as indicated by the growth rings in the pits and the continuation of damage on the youngest branches
 Apart from cutting down a 200 year old tree or camping out by it and do nightly inspections, I can only ask if any of my readers can help solve this intriguing mystery
For more images click HERE

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Wandoo Crown Decline

18/5/2018

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PictureEpicormic shoot (left), dead shoot (right)
Greetings fellow Foxies,
 Have you noticed large numbers of dead leaves on local wandoos, particularly where a whole twig or small branch has died?
This condition where wandoos die back and leave dead branches projecting though the leaf canopy is called Wandoo Crown Decline. This is a cyclical problem that caused huge damage in the 1990’s when the Wandoo Recovery Group was formed.

Research showed that boring insects and associated pathogenic fungi, are the principal agents disrupting stem nutrient and water conducting channels. Symptoms are worse in dry autumns, but underlying factors driving the long term cycle are unresolved.
This autumn I couldn’t find any pattern of areas affected. There are a couple of monitoring sites in Foxes Lair that don’t appear to have a lot of very recent damage. Affected trees in Foxes Lair seem to be randomly distributed, but badly affected ones have obviously been repeatedly attacked.
Being a loyal citizen scientist, I nipped out and sampled a couple of branches from a badly affected tree for close analysis.
My first observation was that the branches were distorted and gangly with lots of dead lower shoots, stems with dark cankers (sunken dead lesions) and resprouting shoots. Clearly not a single year problem.
Looking closely, it was amazing to see so many things attacking the tree. I found stem and leaf galls, and leaf damage from a range of chewing insects, but the real cause of branch death is inside the stems.

The insect involved is a jewel beetle Cisseis fascigera). Beetles emerge from November to February, mate and lay eggs on stems. The larva that looks like a witchetty grub chews tissue and wood inside and along the stems (longitudinal galleries), before pupating in its gallery and emerging a year later.
Unfortunately the insect introduces spores of rot fungi that spread through the stem.
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Intact branch showing exterior hole
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split branch showing the larva in its gallery
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Intact and split stem (frass is entomologist name for poo)
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I split the sections of stem down each branch and was shocked by the extent of fungal invasion that is easily seen as dark stained tissue. On these branches fungus is doing more damage than the insects.
Tissue is often infected with few external symptoms
 The branch1 stem on the far left shows fungal staining only around a gallery between the bark and the wood. In the split section you can see that the fungus is more extensive in the wood.
 In branch 2 infection has spread down the stem from a dead part.
The following images shows how the fungus symptoms progress with age
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No external symptoms. Longitudinal spindle shaped lesions in the sapwood and cambium layer
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Healthy epicormic shoot on a diseased stem being invaded by fungus
PictureSunken fungal canker lesion on stem surface

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External disease that has spread from a canker then exposed internal dead wood.
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Other borers like this large longicorn beetle larva could also be involved

​References


Wandoo Recovery Group report


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Beautiful Australian Bark

13/12/2017

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Greetings fellow Foxies,
No, this is not an exposition on shock jocks or pompous politicians.
Every year I marvel at the lovely colours and textures of  our eucalypts when they are shedding old bark. This, in addition to their unique flowers make them amazing, and underappreciated by most Australians.
The arboretum is a good place to see the range of bark types, particularly in the summer/autumn. This Foxypress shows the progression of bark regrowth in brown mallet, and I hope you enjoy the sample of other trees below.
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Sheoaks and Tammars

26/6/2016

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​Belonging to the Casuarinaceae family, these plants are instantly recognised by their needle-like foliage and the wonderful sighing sound of the wind passing through them. Around Narrogin we tend to notice the trees most: Rock Sheoak; Allocasuarina huegeliana on well drained soils, and Salt Sheoak; Casuarina obesa in semi saline lakes and waterways. A bed of sheoak needles with a whispering wind overhead is a wonderful place for courting couples (after they have repelled the ants, ticks and mosquitos).
The common name Sheoak was first given to Rock Sheoak by early European settlers who thought the wood resembeld that of the European oak but was inferior, and being sexists called it she-oak. 
The genus name Casuarina is derived from the Malay word for cassowary, due to similarities of layered feathers/ needles. If you look closely at a needle you will notice rings of scales, which are the true leaves. The green needles are in fact photosynthesising stems. Casuarinas and Allocasuarinas have subtle differences in cone structure and needle orientation. Allocasuarina means opposite to Casuarina, referring to needle orientation.
Tammas or tammars, are shrubs, which become dominant on gravelly soils generally east of a line through Yealering and Harrismith.
 
Casuarinaceae have male and female plants (dioecious), but differ from the animal world in that the females have the nuts (cones). 
Male plants produce pollen that is blown by wind to female flowers. Like most wind pollinated species, huge amounts of pollen are produced, and you will notice now green female and orange pollen-bearing males everywhere.
​In our bush the vast majority of plants in the bush have root modifications (cluster or proteoid roots) and alliances with fungi (mycorrhizas), which enhance their ability to access nutrients and water and to build a 'niche' to give them an advantage over others. 
Plants on poor sand or gravel soils often have cluster roots that are also instrumental in forming gravels.
Eucalypts and other plants on more fertile soils mainly use mycorrhizas.
Casuarinaceae are very adaptable. They have cluster roots, ectomycorrhizas (where the fungus does not invade the plant root), AND nodules where bacteria produce nitrogen like legumes.
 
Allocasuarina huegeliana was named Rock Sheoak because it mostly occurred around granite rock outcrops. Competition by other plants and grazing of seedlings by by native marsupials restricted their spread. Small marsupial extinction has allowed the sheoaks to spread, and thick needle  cover  suppresses other plants.   Since European settlement they have spread greatly on roadsides and other well drained areas of bush. I frequently see roads with remnant wandoo vegetation on one side of a road and rock sheoak thicket on the disturbed other side. 
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Rock Sheoak female flower and cone
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Male Rock Sheoak loaded with pollen
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Mixed male and female trees
narrogin_sheoaks_tammas.pdf
File Size: 270 kb
File Type: pdf
Download File

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Female (left) and male dwarf sheoak
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Wheatbelt Tammar Allocasuarina campestris
There are lots of tammas (all Allocasuarinas), particularly on kwongan soils, which are often overlooked because they don’t have conventional flowers. Foxes Lair has Dwarf Sheoak; Allocasuarina humilis on gravels, and Allocasuarina microstachyia that only occurs on the south side of the Claypit.
My favourite is the compass bush; Allocasuarina pinaster, which occurs in the Lake Grace area on grey sandy gravels. The nearest Location is Holden Road near Tarin Rock. 
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Compass bush plant
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Compass bush fruit
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Marri decline

9/3/2016

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Greetings fellow Foxies,
Marri trees are flowering profusely this year, possibly due to the February rains. However I have noticed a lot of red gum oozing from adult trees and a few have died spontaneously in recent years. The penny dropped when I saw beautiful adult marris in a Perth (and later Narrogin) garden with unblemished bark, in stark contrast to scabby specimens in Foxes Lair. The gum is a defence mechanism against damage by mainly woodborers. 
As Foxes Lair is on the eastern edge of marri range, marris are under more water stress, slower growing, and more susceptible to parasites.
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Young tree in full flower
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Foxes Lair (left) and Perth garden (right) trunks
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Gum flow
There are still some magnificent and ancient marris in Foxes Lair like the fire damaged specimen on the left, that still manage to produce a flower or two.
However as rainfall decreases and temperatures rise I fear that marri, jarrah and bull banksia may slowly be replaced by scrub and mallees in the reserve.


A number of factors have been suggested
  • Marri Canker (Quamabalaria coryecup) disease is killing marris in higher rainfall areas. Luckily I haven’t seen the characteristic symptoms here
  • Wildfire damage. Marri is more susceptible to fire damage than jar and wandoo. I went to an area opposite Williams Road that had marris scattered in amongst dense Dryandra nobilis scrub where the fire was most intense in 2009, and sure enough found clear fire damage. Interestingly the scars had healed with relatively little associated insect damage, and on closer observation I noticed that the scar often been affected by prior damage as there were 2 concentric scars and the exposed wood was sometimes burnt. The reserve was burnt in the 1970’s and 4WD vehicles also used to career through the bush and may have damaged trees. I also noticed that younger trees were less likely to have the scars. Regular low intensity fires that don't burn through the outer bark promote healthier trees that are more able to resist insect attack. I have recommended that scheduled cool burns in a mosaic pattern with each bay burnt every 10+ year to keep biodiversity in the reserve be included in the Foxes Lair management plan.
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Probable fire damage
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Possible fire damage
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Secondary burn on old fire lesion
  • Borer damage can be easily spotted by copious outpouring of kino (red gum) from a single point, and sometimes a multiple exudations it bark splits. Kino outpours are a natural reaction from the tree to drown invading insects. Water-stressed trees are more liable to insect attack because there is less and thicker kino and it has more sugars that attract insects. The warming climate is also affecting insects’ biology by making them come out of dormancy earlier. DPAW was investigating insect damage in the reserve in the late nineties.
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Copious kino from a hole
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bark shaved off to show insect holes
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Bullseye borer escape hole
  • Spontaneous splitting? DPAW colleague Peter White reminded me that gum bands occur routinely in marri wood, and that some smooth barked eucalypts have splits in their bark following large variations in rainfall.
    A lot of these splits have healed.
    When I shaved the rough bark back from a split, I found live flesh underneath the split with bark on either side. I have also noticed tumorous type growths on old marri branches, but suspect insect involvement.
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Split and growths
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bark scraped off split to show underlying growth
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Growths on live and dead branch
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    Doug Sawkins is a friend of Foxes Lair 

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