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.

Greetings fellow Foxies,
                                 
Witches broom or little leaf disease is a hormone-induced growth distortion of woody plants that only affects part of the plant.
 
In a prior Foxypress I discussed galls that differ from the strange and miniature witches broom shoots and leaves that are induced by insect spread viruses and phytoplasma (primitive bacteria), or fungal infection.
The image on the left shows a wandoo affected by witch's broom near the Marri picnic area.

3 Below are images of witches broom  caused by A rust fungus Ceratacoma jacksoniae that affects a range of pea flowers, also causes a type of witches broom. Images below show an infection on stinkwood (Jacksonia epiphyllum). The strange red growths contain tiny reddish fruiting rods that are quite different from the powdery pustules that occur on our crops.

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.

A couple of months I noticed that some mallees near the Foxes Lair entry track had distorted leaves that were covered with lumpy galls. The mallee is Eucalyptus intrasylvatica, a hybrid derived from E. incrassata that is also called lerp mallee. There is a significant lerp infestation on Foxes Lair wandoos at the moment.
Thinking that lerps were all leaf sucking insects that hid under translucent shell-shaped cases, I googled lerp to find that this refers to the sugary case, and not the insect beneath that is called a psyllid; and that psyllids also cause galls. Adult psyllids look a bit like  small cicadas but are related to aphids and scale insects.
click here for more psyllid information.
Galls develop when leaves are sucked by the juveniles; these change into adults that erupt out of the gall: (remember the movie ‘Alien’?)
Alan Kerrigan took images of horn-shaped lerps and also psyllids below that he found in a round acacia gall.
See also round type lerps on a eucalypt, and winged adult psyllids that are being tended by ants.

Some manna wattles on the Banksia walk are so heavily infested with galls that they appear to be festooned with round fruits like berries or nuts.
When curiosity overcame me and I opened a few to have a look, my eyes encountered maggots instead of          psyllids. The maggots are larvae of the gall-midge (in actual fact a Cecidomyidae fly) that produces a salivary substance which forces acacias to produce gall cells. These have replaced flowers making the plant look like it has fruit.