Giant balga at Candy Block The balga Xanthorrhoea preissii, a grass tree, is a striking part of our bush that was use by Noongars for medicine, tools and sustenance. Grass trees are monocotyledons but neither grasses nor trees.
Carbon dating has found grass tree ages of up to 1,000 years. Also, they have special contractile roots that pull seedlings underground so that plants on sandy soils may not develop an above ground stem for 10 to 30 years. I reckon that the five-metre plant I found in Candy Block must be ancient. Unfortunately, twenty-eight parrots are now attacking its new growth.
The grass tree at Foxes Lair is the smaller Xanthorrhoea brevistyla that lacks an above ground trunk. It is an insect magnet when flowering in November.
I regularly see severe insect attack on balga flowering spikes and brought one home for examination. The green stem had frequent reddish- brown sunken lesions with gum exuding from small holes. The split stem revealed tunnels containing bardi grubs, surrounded by reddish brown fungal infection. Once again, a canker fungus that affects eucalypts and other shrubs
Carbon dating has found grass tree ages of up to 1,000 years. Also, they have special contractile roots that pull seedlings underground so that plants on sandy soils may not develop an above ground stem for 10 to 30 years. I reckon that the five-metre plant I found in Candy Block must be ancient. Unfortunately, twenty-eight parrots are now attacking its new growth.
The grass tree at Foxes Lair is the smaller Xanthorrhoea brevistyla that lacks an above ground trunk. It is an insect magnet when flowering in November.
I regularly see severe insect attack on balga flowering spikes and brought one home for examination. The green stem had frequent reddish- brown sunken lesions with gum exuding from small holes. The split stem revealed tunnels containing bardi grubs, surrounded by reddish brown fungal infection. Once again, a canker fungus that affects eucalypts and other shrubs
 Bardi grubs inside fungus infected galleries |  Sunken brown lesions and gum exuding from borer holes |
Interestingly, a previous investigation on wandoo crown decline in Foxes Lair found a similar combination of insects and fungus. The fungus causes severe damage to trees and shrubs. Fungus doesn’t seem to affect the balga trunk, presumably because flowering spikes naturally die before it can spread further.
The bardi grubs are larvae of longicorn and cockchafer beetles. They have tunnelled up through the entire flowering stem.
The flowers and seeds were attacked by a brownish caterpillar that eats them under a protective cover it makes from its frass (poo) and silk.
The bardi grubs are larvae of longicorn and cockchafer beetles. They have tunnelled up through the entire flowering stem.
The flowers and seeds were attacked by a brownish caterpillar that eats them under a protective cover it makes from its frass (poo) and silk.
Last year I received a shock when one of two apparently healthy balgas that I had photographed earlier snapped off at mid stem
 Before |  After |
The centre of a normal trunk is filled with living fibrous material above a woody cone-shaped base that remains long after a plant has died. The living centre is surrounded by old leaf bases held together by natural resin, which provides support and excellent fire protection.
The fibrous centre of the dead balga was completely replaced by a soil-like material containing wireworms, which were attacking the interior of the surrounding leaf bases
The fibrous centre of the dead balga was completely replaced by a soil-like material containing wireworms, which were attacking the interior of the surrounding leaf bases
 wireworms in rotted grass tree centre |  surrounding leaf bases being eaten |
As Noongars ate bardi grubs that were in the centre of dead balgas, I suspect that they had chewed out the living material before wireworms moved in.
This balga had been surviving with a decayed centre for some time until the weakened stem snapped. It is a natural process and dead remnants can be attractive in their own right.
Unfortunately, increased in Australian ringneck parrot (twenty eight) numbers are causing premature balga death from them continuously chewing the new growth.
This balga had been surviving with a decayed centre for some time until the weakened stem snapped. It is a natural process and dead remnants can be attractive in their own right.
Unfortunately, increased in Australian ringneck parrot (twenty eight) numbers are causing premature balga death from them continuously chewing the new growth.
 Balga killed by grubs |  Balga being killed by twenty eight parrots |